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Bibliography on: Symbiosis

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ESP: PubMed Auto Bibliography 05 Jul 2020 at 01:35 Created: 

Symbiosis

Symbiosis refers to an interaction between two or more different organisms living in close physical association, typically to the advantage of both. Symbiotic relationships were once thought to be exceptional situations. Recent studies, however, have shown that every multicellular eukaryote exists in a tight symbiotic relationship with billions of microbes. The associated microbial ecosystems are referred to as microbiome and the combination of a multicellular organism and its microbiota has been described as a holobiont. It seems "we are all lichens now."

Created with PubMed® Query: symbiosis NOT pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)

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RevDate: 2020-07-03

Si Z, Guan N, Zhou Y, et al (2020)

A Methionine Sulfoxide Reductase B is Required for the Etablishment of Astragalus sinicus-Mesorhizobium Symbiosis.

Plant & cell physiology pii:5866985 [Epub ahead of print].

Methionine sulfoxide reductase B (MsrB) is involved in oxidative stress or defense responses in plants. However, little is known about its role in legume-rhizobium symbiosis. In this work, an MsrB gene was identified from Astragalus sinicus and its function in symbiosis was characterized. AsMsrB was induced under phosphorus starvation and displayed different expression patterns under symbiotic and non-symbiotic conditions. Hydrogen peroxide or methyl viologen treatment enhanced the transcript level of AsMsrB in roots and nodules. Subcellular localization showed that AsMsrB was localized in the cytoplasm of onion epidermal cells and co-localized with rhizobia in nodules. Plants with AsMsrB-RNAi hairy roots exhibited significant decreases in nodule number, nodule nitrogenase activity and fresh weight of aerial part, as well as abnormal nodule and symbiosome development. Statistics of infection events showed that plants with AsMsrB-RNAi hairy roots had significant decreases in the number of root hair curling events, infection threads and nodule primordia compared with the control. The content of hydrogen peroxide increased in AsMsrB-RNAi roots while decreased in AsMsrB over-expression roots at the early stage of infection. The transcriptome analysis showed synergistic modulations of the expression of genes involved in ROS generation and scavenging, defense and pathogenesis, and early nodulation. In addition, a candidate protein interacting with AsMsrB was identified and confirmed by bimolecular fluorescence complementation. Taken together, our results indicate that AsMsrB plays an essential role in nodule development and symbiotic nitrogen fixation by affecting the redox homeostasis in roots and nodules.

RevDate: 2020-07-03

Jang SW, Yoou MH, Hong WJ, et al (2020)

Re-Analysis of 16S Amplicon Sequencing Data Reveals Soil Microbial Population Shifts in Rice Fields under Drought Condition.

Rice (New York, N.Y.), 13(1):44 pii:10.1186/s12284-020-00403-6.

Rice (Oryza sativa. L) has been intensively studied to ensure a stable global supply of this commodity in the face of rapid global climate change. A critical factor that decreases crop yield is drought, which has been analyzed in various ways through many researches. Microbiome-based studies of rice investigate the symbiosis between rice and bacteria, which has been proposed as a way to overcome problems caused by drought. Several rice-associated metagenomic profiles obtained under drought conditions have been reported since the advent of next generation sequencing (NGS) technology. To elucidate the future diversity of plants and microorganisms and to promote sustainable agriculture, we reanalyzed 64 of the publicly available 16S amplicon sequencing data produced under drought condition. In the process of integrating data sets, however, we found an inconsistency that serves as a bottleneck for microbiome-based sustainability research. While this report provides clues about the composition of the microbiome under the drought conditions, the results are affected by differences in the location of the experiments, sampling conditions, and analysis protocols. Re-analysis of amplicon sequencing data of the soil microbiome in rice fields suggests that microbial composition shifts in response to drought condition and the presence of plants. Among the bacteria involved, the phylum Proteobacteria appears to play the most important role in the survival of rice under drought condition.

RevDate: 2020-07-03

Preethish-Kumar V, Shah A, Kumar M, et al (2020)

In Vivo Evaluation of White Matter Abnormalities in Children with Duchenne Muscular Dystrophy Using DTI.

AJNR. American journal of neuroradiology pii:ajnr.A6604 [Epub ahead of print].

BACKGROUND AND PURPOSE: Duchenne muscular dystrophy is an X-linked disorder characterized by progressive muscle weakness and prominent nonmotor manifestations, such as a low intelligence quotient and neuropsychiatric disturbance. We investigated WM integrity in patients with Duchenne muscular dystrophy using DTI.

MATERIALS AND METHODS: Fractional anisotropy and mean, axial, and radial diffusivity (DTI measures) were used to assess WM microstructural integrity along with neuropsychological evaluation in patients with Duchenne muscular dystrophy (n = 60) and controls (n = 40). Exon deletions in the DMD gene were confirmed using multiplex ligation-dependent probe amplification. Patients were classified into proximal (DMD Dp140+) and distal (DMD Dp140-) subgroups based on the location of the exon deletion and expression of short dystrophin Dp140 isoform. WM integrity was examined using whole-brain Tract-Based Spatial Statistics and atlas-based analysis of DTI data. The Pearson correlation was performed to investigate the possible relationship between neuropsychological scores and DTI metrics.

RESULTS: The mean ages of Duchenne muscular dystrophy and control participants were 8.0 ± 1.2 years and 8.2 ± 1.4 years, respectively. The mean age at disease onset was 4.1 ± 1.8 years, and mean illness duration was 40.8 ± 25.2 months. Significant differences in neuropsychological scores were observed between the proximal and distal gene-deletion subgroups, with more severe impairment in the distal-deletion subgroup (P < .05). Localized fractional anisotropy changes were seen in the corpus callosum, parietal WM, and fornices in the patient subgroup with Dp140+, while widespread changes were noted in the Dp140- subgroup. The Dp140+ subgroup showed increased axial diffusivity in multiple WM regions relative to the Dp140- subgroup. No significant correlation was observed between clinical and neuropsychological scores and diffusion metrics.

CONCLUSIONS: Widespread WM differences are evident in patients with Duchenne muscular dystrophy relative to healthy controls. Distal mutations in particular are associated with extensive WM abnormalities and poor neuropsychological profiles.

RevDate: 2020-07-03

Koch EJ, Moriano-Gutierrez S, Ruby EG, et al (2020)

The impact of persistent colonization by Vibrio fischeri on the metabolome of the host squid Euprymna scolopes.

The Journal of experimental biology pii:jeb.212860 [Epub ahead of print].

Associations between animals and microbes affect not only the immediate tissues where they occur, but also the entire host. Metabolomics, the study of small biomolecules generated during metabolic processes, provides a window into how mutualistic interactions shape host biochemistry. The Hawaiian bobtail squid, Euprymna scolopes, is amenable to metabolomic studies of symbiosis because the host can be reared with or without its species-specific symbiont, Vibrio fischeri In addition, unlike many invertebrates, the host squid has a closed circulatory system. This feature allows a direct sampling of the refined collection of metabolites circulating through the body, a focused approach that has been highly successful with mammals. Here, we show that rearing E. scolopes without its natural symbiont significantly affected one quarter of the more than 100 hemolymph metabolites defined by gas chromatography mass-spectrometry analysis. Further, as in mammals, which harbor complex consortia of bacterial symbionts, the metabolite signature oscillated on symbiont-driven daily rhythms and was dependent on the sex of the host. Thus, our results provide evidence that the population of even a single symbiont species can influence host hemolymph biochemistry as a function of symbiotic state, host sex, and circadian rhythm.

RevDate: 2020-07-03

Bréchignac F (2020)

Neglecting the ecosystemic dimension of life hinders efficient environmental protection from radiation and other hazards.

International journal of radiation biology [Epub ahead of print].

Purpose Recent efforts undertaken by the radioecology community to protect the environment against radiation have largely ignored the ecosystem concept. Instead, it has simply transferred to non human biota the concepts and methods developped for human radioprotection. This oversimplification, rooted within a narrow anthropocentric view dominating radiation protection, is prone to lead ecological risk assessment to miss its objectives.Conclusions One key challenge for radiation research when facing this general context is to widen traditional radiation biology, focused on DNA and cells of individual organisms, towards radiation ecology featuring an ecosystem-centered conceptualization. If life is driven by processes that act at subsystem level, i.e. the molecular engineering that founds the organisms' physiology, it depends as well on processes that act at system level, i.e. emergent properties of the ecosystem dimension (life support, symbiosis, resilience, biodiversity,…) since both types of processes have jointly emerged through evolution. It is worthwhile strengthening that this problem is not specific to radiation protection only. Organisms and populations of species only exist as embedded within an ecosystem featuring multispecies interactions. Ecosystems exhibit specific behaviors that find pertinent explanation through the complex systems theory, and this leads to several implications for ecological risk assessment in general. Environment protection measures that are developed exclusively from subsystem understanding (dose-response curves established for individual organisms) for practical reasons, as in current protection guidance, may actually miss their protection objective and explain some recently reported discrepancies in assessing ecological impact. Indeed, one observes that none of the methodologies in use today for environmental risk assessment has allowed to predict the ongoing dramatic biodiversity decline. It is strengthened finally that most current critical environmental issues such as global change, biodiversity decline, pollutions impact, etc…, are ecosystem-centered, and as such, they cannot be correctly understood without adopting more ecocentric approaches.

RevDate: 2020-07-03
CmpDate: 2020-07-03

Russell SL, Chappell L, W Sullivan (2019)

A symbiont's guide to the germline.

Current topics in developmental biology, 135:315-351.

Microbial symbioses exhibit astounding adaptations, yet all symbionts face the problem of how to reliably associate with host offspring every generation. A common strategy is vertical transmission, in which symbionts are directly transmitted from the female to her offspring. The diversity of symbionts and vertical transmission mechanisms is as expansive as the diversity of eukaryotic host taxa that house them. However, there are several common themes among these mechanisms based on the degree to which symbionts associate with the host germline during transmission. In this review, we detail three distinct vertical transmission strategies, starting with associations that are transmitted from host somatic cells to offspring somatic cells, either due to lacking a germline or avoiding it. A second strategy involves somatically-localized symbionts that migrate into the germline during host development. The third strategy we discuss is one in which the symbiont maintains continuous association with the germline throughout development. Unexpectedly, the vast majority of documented vertically inherited symbionts rely on the second strategy: soma-to-germline migration. Given that not all eukaryotes contain a sequestered germline and instead produce offspring from somatic stem cell lineages, this soma-to-germline migration is discussed in the context of multicellular evolution. Lastly, as recent genomics data have revealed an abundance of horizontal gene transfer events from symbiotic and non-symbiotic bacteria to host genomes, we discuss their impact on eukaryotic host evolution.

RevDate: 2020-07-02

Rizzo AE, Almeida Dos Santos S, E da Conceição Guerreiro Couto (2020)

First report of Labrorostratus caribensis (Annelida, Oenonidae) as endoparasite of Haplosyllis rosenalessoae (Annelida, Syllidae) from Brazil.

International journal for parasitology. Parasites and wildlife, 12:64-66 pii:S2213-2244(20)30038-9.

In this study, we report the second endoparasitic relationship for the oenonid Labrorostratus caribensis, previously described parasitizing a nereid polychaete. The new host is the syllid Haplosyllis rosenalessoae, in which it occupies 2/3 of its body cavity host. This is the second endoparasitic relationship between polychaetes and the first between both partners in known for Brazil, as well as the first record of the parasite outside the type locality (Caribbean) and of the host in the State of Bahia. We discuss on the interest of the finding of these king of parasitic relationships and provide an identification key to all knwon species of Labrorostratus.

RevDate: 2020-07-02

Ranjbar Sistani N, Desalegn G, Kaul HP, et al (2020)

Seed Metabolism and Pathogen Resistance Enhancement in Pisum sativum During Colonization of Arbuscular Mycorrhizal Fungi: An Integrative Metabolomics-Proteomics Approach.

Frontiers in plant science, 11:872.

Pulses are one of the most important categories of food plants, and Pea (Pisum sativum L.) as a member of pulses is considered a key crop for food and feed and sustainable agriculture. Integrative multi-omics and microsymbiont impact studies on the plant's immune system are important steps toward more productive and tolerant food plants and thus will help to find solutions against food poverty. Didymella pinodes is a main fungal pathogen of pea plants. Arbuscular mycorrhizal fungi (AMF) promote plant growth and alleviate various stresses. However, it remained unclear as to how the AMF effect on seed metabolism and how this influences resistance against the pathogen. This study assesses the AMF impacts on yield components and seed quality upon D. pinodes infection on two different P. sativum cultivars, susceptible versus tolerant, grown in pots through phenotypic and seed molecular analyses. We found that AMF symbiosis affects the majority of all tested yield components as well as a reduction of disease severity in both cultivars. Seeds of mycorrhizal pea plants showed strong responses of secondary metabolites with nutritional, medicinal, and pharmaceutical attributes, also involved in pathogen response. This is further supported by proteomic data, functionally determining those primary and secondary metabolic pathways, involved in pathogen response and induced upon AMF-colonization. The data also revealed cultivar specific effects of AMF symbiosis that increase understanding of genotype related differences. Additionally, a suite of proteins and secondary metabolites are presented, induced in seeds of P. sativum upon AMF-colonization and pathogen attack, and possibly involved in induced systemic resistance against D. pinodes, useful for modern breeding strategies implementing microsymbionts toward increased pathogen resistance.

RevDate: 2020-07-02

Egan S, Fukatsu T, MP Francino (2020)

Opportunities and Challenges to Microbial Symbiosis Research in the Microbiome Era.

Frontiers in microbiology, 11:1150.

RevDate: 2020-07-02

Hashimoto S, Goto K, Pyromyou P, et al (2020)

Type III Secretion System of Bradyrhizobium sp. SUTN9-2 Obstructs Symbiosis with Lotus spp.

Microbes and environments, 35(3):.

The rhizobial type III secretion system secretes effector proteins into host plant cells, which may either promote or inhibit symbiosis with legumes. We herein demonstrated that the type III secretion system of Bradyrhizobium sp. SUTN9-2 obstructed symbiosis with Lotus japonicus Miyakojima, L. japonicus Gifu, and Lotus burttii. A mutant of SUTN9-2 that is unable to secrete effector proteins showed better nodulation and plant growth promotion than wild-type SUTN9-2 when paired with these Lotus spp. We propose that SUTN9-2 is a useful strain for understanding the mechanisms by which effector proteins obstruct symbiosis between Bradyrhizobium and Lotus spp.

RevDate: 2020-07-02
CmpDate: 2020-07-02

Roossinck MJ (2019)

Viruses in the phytobiome.

Current opinion in virology, 37:72-76.

The phytobiome, defined as plants and all the entities that interact with them, is rich in viruses, but with the exception of plant viruses of crop plants, most of the phytobiome viruses remain very understudied. This review focuses on the neglected portions of the phytobiome, including viruses of other microbes interacting with plants, viruses in the soil, viruses of wild plants, and relationships between viruses and the vectors of plant viruses.

RevDate: 2020-07-02
CmpDate: 2020-07-02

Seo SU, MN Kweon (2019)

Virome-host interactions in intestinal health and disease.

Current opinion in virology, 37:63-71.

The enteric virome consists largely of bacteriophages and prophages related to commensal bacteria. Bacteriophages indirectly affect the host immune system by targeting their associated bacteria; however, studies suggest that bacteriophages also have distinct pathways that enable them to interact directly with the host. Eukaryotic viruses are less abundant than bacteriophages but are more efficient in the stimulation of host immune responses. Acute, permanent, and latent viral infections are detected by different types of pattern recognition receptors and induce host immune responses, including the antiviral type I interferon response. Understanding the complex interplay between commensal microorganisms and the host immune system is a prerequisite to elucidating their role in intestinal diseases.

RevDate: 2020-07-02
CmpDate: 2020-07-02

Beller L, J Matthijnssens (2019)

What is (not) known about the dynamics of the human gut virome in health and disease.

Current opinion in virology, 37:52-57.

The human gut virome has an important role in human health but its dynamics remain poorly understood. Few longitudinal studies in healthy adults showed a stable temporal gut virome, with high inter-individual diversity. In contrast, the infant virome shows a high temporal intra-individual diversity. Unfortunately, these virome studies ignore an enormous amount of unknown 'dark matter' sequences, leading to incomplete analyses and possibly incorrect conclusions. Also, the interactions between prokaryotes and bacteriophages in the gut seem to be too complex for currently available models. Therefore, there is a huge need of larger longitudinal cohort studies focusing on both the bacterial and viral component of the microbiome to be able to describe and understand this complex ecosystem.

RevDate: 2020-07-02
CmpDate: 2020-07-02

Winkler ES, LB Thackray (2019)

A long-distance relationship: the commensal gut microbiota and systemic viruses.

Current opinion in virology, 37:44-51.

Recent advances defining the role of the commensal gut microbiota in the development, education, induction, function, and maintenance of the mammalian immune system inform our understanding of how immune responses govern the outcome of systemic virus infection. While characterization of the impact of the local oral, respiratory, dermal and genitourinary microbiota on host immune responses and systemic virus infection is in its infancy, the gut microbiota interacts with host immunity systemically and at distal non-gastrointestinal tract sites to modulate the pathogenesis of systemic viruses. Gut microbes, microbe-associated molecular patterns, and microbe-derived metabolites engage receptors expressed on the cell surface, in the endosome, or in the cytoplasm to orchestrate optimal innate and adaptive immune responses important for controlling systemic virus infection.

RevDate: 2020-07-02
CmpDate: 2020-07-02

Thu MJ, Qiu Y, Kataoka-Nakamura C, et al (2019)

Isolation of Rickettsia, Rickettsiella, and Spiroplasma from Questing Ticks in Japan Using Arthropod Cells.

Vector borne and zoonotic diseases (Larchmont, N.Y.), 19(7):474-485.

Ticks are blood-sucking ectoparasites that transmit zoonotic pathogens to humans and animals. Ticks harbor not only pathogenic microorganisms but also endosymbionts. Although some tick endosymbionts are known to be essential for the survival of ticks, their roles in ticks remain poorly understood. The main aim of this study was to isolate and characterize tick-borne microorganisms from field-collected ticks using two arthropod cell lines derived from Ixodes scapularis embryos (ISE6) and Aedes albopictus larvae (C6/36). A total of 170 tick homogenates originating from 15 different tick species collected in Japan were inoculated into each cell line. Bacterial growth was confirmed by PCR amplification of 16S ribosomal DNA (rDNA) of eubacteria. During the 8-week observation period, bacterial isolation was confirmed in 14 and 4 samples using ISE6 and C6/36 cells, respectively. The sequencing analysis of the 16S rDNA PCR products indicated that they were previously known tick-borne pathogens/endosymbionts in three different genera: Rickettsia, Rickettsiella, and Spiroplasma. These included four previously validated rickettsial species namely Rickettsia asiatica (n = 2), Rickettsia helvetica (n = 3), Rickettsia monacensis (n = 2), and Rickettsia tamurae (n = 3) and one uncharacterized genotype Rickettsia sp. LON (n = 2). Four isolates of Spiroplasma had the highest similarity with previously reported Spiroplasma isolates: Spiroplasma ixodetis obtained from ticks in North America and Spiroplasma sp. Bratislava 1 obtained from Ixodes ricinus in Europe, while two isolates of Rickettsiella showed 100% identity with Rickettsiella sp. detected from Ixodes uriae at Grimsey Island in Iceland. To the best of our knowledge, this is the first report on successful isolation of Rickettsiella from ticks. The isolates obtained in this study can be further analyzed to evaluate their pathogenic potential in animals and their roles as symbionts in ticks.

RevDate: 2020-07-01

Attané C, C Muller (2020)

Drilling for Oil: Tumor-Surrounding Adipocytes Fueling Cancer.

Trends in cancer, 6(7):593-604.

Over the past decade, it has become apparent that metabolic reprogramming is a key event in tumor progression. The tumor microenvironment (TME) is a source of metabolites for tumor cells. Lipid-filled mature adipocytes are frequently found in proximity to invasive human tumors and release free fatty acids (FFAs) through lipolysis. These FFAs are taken up by tumor cells and used to promote tumor progression by mechanisms that include mitochondrial fatty acid oxidation (FAO). This review discusses recent advances in our understanding of this metabolic symbiosis between adipocytes and cancer cells and underlines the differences in this metabolic crosstalk between the various types of cancer and their localization.

RevDate: 2020-07-01

Cabello AM, Turk-Kubo KA, Hayashi K, et al (2020)

Unexpected presence of the nitrogen-fixing symbiotic cyanobacterium UCYN-A in Monterey Bay, California.

Journal of phycology [Epub ahead of print].

In the last decade, the known biogeography of nitrogen fixation in the ocean has been expanded to colder and nitrogen-rich coastal environments. The symbiotic nitrogen-fixing cyanobacteria group A (UCYN-A) has been revealed as one of the most abundant and widespread nitrogen-fixers, and includes several sublineages that live associated with genetically distinct but closely related prymnesiophyte hosts. The UCYN-A1 sublineage is associated with an open ocean picoplanktonic prymnesiophyte, whereas UCYN-A2 is associated with the coastal nanoplanktonic coccolithophore Braarudosphaera bigelowii, suggesting that different sublineages may be adapted to different environments. Here, we study the diversity of nifH genes present at the Santa Cruz Municipal Wharf in the Monterey Bay (MB), California, and report for the first time the presence of multiple UCYN-A sublineages, unexpectedly dominated by the UCYN-A2 sublineage. Sequence and quantitative PCR data over an 8-year time-series (2011-2018) show a shift towards increasing UCYN-A2 abundances after 2013, and a marked seasonality for this sublineage which was present during summer-fall months, coinciding with the upwelling-relaxation period in the MB. Increased abundances corresponded to positive temperature anomalies in MB, and we discuss the possibility of a benthic life stage of the associated coccolithophore host to explain the seasonal pattern. The dominance of UCYN-A2 in coastal waters of the MB underscores the need to further explore the habitat preference of the different sublineages in order to provide additional support for the hypothesis that UCYN-A1 and UCYN-A2 sublineages are different ecotypes.

RevDate: 2020-07-01

Altamia MA, Lin Z, Trindade-Silva AE, et al (2020)

Secondary Metabolism in the Gill Microbiota of Shipworms (Teredinidae) as Revealed by Comparison of Metagenomes and Nearly Complete Symbiont Genomes.

mSystems, 5(3): pii:5/3/e00261-20.

Shipworms play critical roles in recycling wood in the sea. Symbiotic bacteria supply enzymes that the organisms need for nutrition and wood degradation. Some of these bacteria have been grown in pure culture and have the capacity to make many secondary metabolites. However, little is known about whether such secondary metabolite pathways are represented in the symbiont communities within their hosts. In addition, little has been reported about the patterns of host-symbiont co-occurrence. Here, we collected shipworms from the United States, the Philippines, and Brazil and cultivated symbiotic bacteria from their gills. We analyzed sequences from 22 shipworm gill metagenomes from seven shipworm species and from 23 cultivated symbiont isolates. Using (meta)genome sequencing, we demonstrate that the cultivated isolates represent all the major bacterial symbiont species and strains in shipworm gills. We show that the bacterial symbionts are distributed among shipworm hosts in consistent, predictable patterns. The symbiotic bacteria harbor many gene cluster families (GCFs) for biosynthesis of bioactive secondary metabolites, only <5% of which match previously described biosynthetic pathways. Because we were able to cultivate the symbionts and to sequence their genomes, we can definitively enumerate the biosynthetic pathways in these symbiont communities, showing that ∼150 of ∼200 total biosynthetic gene clusters (BGCs) present in the animal gill metagenomes are represented in our culture collection. Shipworm symbionts occur in suites that differ predictably across a wide taxonomic and geographic range of host species and collectively constitute an immense resource for the discovery of new biosynthetic pathways corresponding to bioactive secondary metabolites.IMPORTANCE We define a system in which the major symbionts that are important to host biology and to the production of secondary metabolites can be cultivated. We show that symbiotic bacteria that are critical to host nutrition and lifestyle also have an immense capacity to produce a multitude of diverse and likely novel bioactive secondary metabolites that could lead to the discovery of drugs and that these pathways are found within shipworm gills. We propose that, by shaping associated microbial communities within the host, the compounds support the ability of shipworms to degrade wood in marine environments. Because these symbionts can be cultivated and genetically manipulated, they provide a powerful model for understanding how secondary metabolism impacts microbial symbiosis.

RevDate: 2020-07-01

Lefoulon E, Clark T, Borveto F, et al (2020)

Pseudoscorpion Wolbachia symbionts: diversity and evidence for a new supergroup S.

BMC microbiology, 20(1):188 pii:10.1186/s12866-020-01863-y.

BACKGROUND: Wolbachia are the most widely spread endosymbiotic bacteria, present in a wide variety of insects and two families of nematodes. As of now, however, relatively little genomic data has been available. The Wolbachia symbiont can be parasitic, as described for many arthropod systems, an obligate mutualist, as in filarial nematodes or a combination of both in some organisms. They are currently classified into 16 monophyletic lineage groups ("supergroups"). Although the nature of these symbioses remains largely unknown, expanded Wolbachia genomic data will contribute to understanding their diverse symbiotic mechanisms and evolution.

RESULTS: This report focuses on Wolbachia infections in three pseudoscorpion species infected by two distinct groups of Wolbachia strains, based upon multi-locus phylogenies. Geogarypus minor harbours wGmin and Chthonius ischnocheles harbours wCisc, both closely related to supergroup H, while Atemnus politus harbours wApol, a member of a novel supergroup S along with Wolbachia from the pseudoscorpion Cordylochernes scorpioides (wCsco). Wolbachia supergroup S is most closely related to Wolbachia supergroups C and F. Using target enrichment by hybridization with Wolbachia-specific biotinylated probes to capture large fragments of Wolbachia DNA, we produced two draft genomes of wApol. Annotation of wApol highlights presence of a biotin operon, which is incomplete in many sequenced Wolbachia genomes.

CONCLUSIONS: The present study highlights at least two symbiont acquisition events among pseudoscorpion species. Phylogenomic analysis indicates that the Wolbachia from Atemnus politus (wApol), forms a separate supergroup ("S") with the Wolbachia from Cordylochernes scorpioides (wCsco). Interestingly, the biotin operon, present in wApol, appears to have been horizontally transferred multiple times along Wolbachia evolutionary history.

RevDate: 2020-07-01
CmpDate: 2020-07-01

Suzuki K (2020)

Diversified IgA-Bacteria Interaction in Gut Homeostasis.

Advances in experimental medicine and biology, 1254:105-116.

Immunoglobulin A (IgA) is the major immunoglobulin isotype produced by the gut immune system, and many studies revealed key roles of IgA in establishing host-bacteria mutualism. This chapter will review current understandings for the function of gut IgA in regulating commensal microbiota. IgA specifically recognizes bacterial species that strongly stimulate host's immune responses, and suppresses their overgrowth or reduces the expressions of bacterial pro-inflammatory genes. On the other hand, IgA coatings on symbiotic bacteria enhance bacteria-mucus and bacteria-bacteria interactions, which induce production of metabolites enforcing mucosal barrier functions. Such diversified effects suggest that multiple factors may be involved in the mechanisms of IgA-bacteria interactions, including IgA specificity to microbial epitopes, mode of cellular responses of IgA synthesis (T-dependent and T-independent) and post-translational modifications of IgA proteins, such as glycosylation.

RevDate: 2020-07-01
CmpDate: 2020-07-01

Martignoni MM, Hart MM, Tyson RC, et al (2020)

Diversity within mutualist guilds promotes coexistence and reduces the risk of invasion from an alien mutualist.

Proceedings. Biological sciences, 287(1923):20192312.

Biodiversity is an important component of healthy ecosystems, and thus understanding the mechanisms behind species coexistence is critical in ecology and conservation biology. In particular, few studies have focused on the dynamics resulting from the co-occurrence of mutualistic and competitive interactions within a group of species. Here we build a mathematical model to study the dynamics of a guild of competitors who are also engaged in mutualistic interactions with a common partner. We show that coexistence as well as competitive exclusion can occur depending on the competition strength and on strength of the mutualistic interactions, and we formulate concrete criteria for predicting invasion success of an alien mutualist based on propagule pressure, alien traits (such as its resource exchange ability) and composition of the recipient community. We find that intra guild diversity promotes the coexistence of species that would otherwise competitively exclude each other, and makes a guild less vulnerable to invasion. Our results can serve as a useful framework to predict the consequences of species manipulation in mutualistic communities.

RevDate: 2020-07-01
CmpDate: 2020-07-01

Trevelline BK, Sosa J, Hartup BK, et al (2020)

A bird's-eye view of phylosymbiosis: weak signatures of phylosymbiosis among all 15 species of cranes.

Proceedings. Biological sciences, 287(1923):20192988.

In numerous animal clades, the evolutionary history of host species drives patterns of gut microbial community structure, resulting in more divergent microbiota with increasing phylogenetic distance between hosts. This phenomenon, termed phylosymbiosis, has been observed in diverse evolutionary lineages, but has been difficult to detect in birds. Previous tests of phylosymbiosis among birds have been conducted using wild individuals, and thus interspecific differences in diet and environment may have masked a phylogenetic signal. Therefore, we tested for phylosymbiosis among all 15 species of cranes (family Gruidae) housed in the same captive environment and maintained on identical diets. 16S rRNA sequencing revealed that crane species harbour distinct gut microbiota. Overall, we detected marginally significant patterns of phylosymbiosis, the strength of which was increased when including the estimates of absolute microbial abundance (rather than relative abundance) derived from microbial densities determined by flow cytometry. Using this approach, we detected the statistically significant signatures of phylosymbiosis only after removing male cranes from our analysis, suggesting that using mixed-sex animal cohorts may prevent the detection of phylosymbiosis. Though weak compared with mammals (and especially insects), these results provide evidence of phylosymbiosis in birds. We discuss the potential differences between birds and mammals, such as transmission routes and host filtering, that may underlie the differences in the strength of phylosymbiosis.

RevDate: 2020-07-01
CmpDate: 2020-07-01

Ibañez S, Medina MI, E Agostini (2020)

Vicia: a green bridge to clean up polluted environments.

Applied microbiology and biotechnology, 104(1):13-21.

Vicia species, commonly known as vetches, include legume plants which nowadays can be found in many countries around the world. Their use to improve soil health and productivity is crucial in management schemes that make sustainable agriculture possible, but they can also play a part in the phytoremediation of polluted environments. Furthermore, they harbor a large community of rhizospheric microorganisms, such as biodegradative bacteria and plant growth-promoting rhizobacteria, which can help to increase phytoremediation efficiency. Their mutualistic association with Rhizobium sp. has also been proposed as an attractive bioremediation tool. Thus, Vicia species could make a remarkable difference in the ecological restoration of polluted soils, thanks to their dual role as cover crops and phytoremediator plants. This mini-review discusses recent advances in the use of Vicia. Challenges and opportunities connect with the application of these species will also be revised, as well as aspects that remain to be explored.

RevDate: 2020-06-30

Rix L, Ribes M, Coma R, et al (2020)

Heterotrophy in the earliest gut: a single-cell view of heterotrophic carbon and nitrogen assimilation in sponge-microbe symbioses.

The ISME journal pii:10.1038/s41396-020-0706-3 [Epub ahead of print].

Sponges are the oldest known extant animal-microbe symbiosis. These ubiquitous benthic animals play an important role in marine ecosystems in the cycling of dissolved organic matter (DOM), the largest source of organic matter on Earth. The conventional view on DOM cycling through microbial processing has been challenged by the interaction between this efficient filter-feeding host and its diverse and abundant microbiome. Here we quantify, for the first time, the role of host cells and microbial symbionts in sponge heterotrophy. We combined stable isotope probing and nanoscale secondary ion mass spectrometry to compare the processing of different sources of DOM (glucose, amino acids, algal-produced) and particulate organic matter (POM) by a high-microbial abundance (HMA) and low-microbial abundance (LMA) sponge with single-cell resolution. Contrary to common notion, we found that both microbial symbionts and host choanocyte (i.e. filter) cells and were active in DOM uptake. Although all DOM sources were assimilated by both sponges, higher microbial biomass in the HMA sponge corresponded to an increased capacity to process a greater variety of dissolved compounds. Nevertheless, in situ feeding data demonstrated that DOM was the primary carbon source for both the LMA and HMA sponge, accounting for ~90% of their heterotrophic diets. Microbes accounted for the majority (65-87%) of DOM assimilated by the HMA sponge (and ~60% of its total heterotrophic diet) but <5% in the LMA sponge. We propose that the evolutionary success of sponges is due to their different strategies to exploit the vast reservoir of DOM in the ocean.

RevDate: 2020-06-29

Chambers SA, SD Townsend (2020)

Like mother, like microbe: human milk oligosaccharide mediated microbiome symbiosis.

Biochemical Society transactions pii:225551 [Epub ahead of print].

Starting shortly after parturition, and continuing throughout our lifetime, the gut microbiota coevolves with our metabolic and neurological programming. This symbiosis is regulated by a complex interplay between the host and environmental factors, including diet and lifestyle. Not surprisingly, the development of this microbial community is of critical importance to health and wellness. In this targeted review, we examine the gut microbiome from birth to 2 years of age to characterize the role human milk oligosaccharides play in early formation of microbial flora.

RevDate: 2020-06-30

Prado-Garcia H, Campa-Higareda A, S Romero-Garcia (2020)

Lactic Acidosis in the Presence of Glucose Diminishes Warburg Effect in Lung Adenocarcinoma Cells.

Frontiers in oncology, 10:807.

Lactic acidosis (3 to 40 mM, pH < 6.9) is a condition found in solid tumors because tumor cells have a high rate of glucose consumption and lactate production even in the presence of oxygen; nevertheless, the microenvironment might still provide a sufficient glucose supply. Lactic acidosis has been proposed to shift metabolism from aerobic glycolysis toward oxidative phosphorylation (OXPHOS). We tested if lung tumor cells cultured under lactic acidosis shift their metabolism from glycolysis to OXPHOS by consuming extracellular lactate, increasing growth rate. We analyzed lung adenocarcinoma (A-549, A-427) cell lines and non-transformed fibroblast cells (MRC-5), which were cultured using RPMI-1640 medium initially containing lactate (2 mM) and glucose (10 mM), at pH 7.2 or 6.2 and oxygen tension 21% O2 (normoxia) or 2% O2 (hypoxia). We obtained growth curves, as well as glucose consumption and lactate production rates (measured during exponential growth) for each cell line. HIF-1α (Hypoxia-inducible factor 1 α), CS (citrate synthase) and AMPK (AMP-activated protein kinase) transcript levels were analyzed using RT-qPCR. By flow cytometry, we determined: (a) expression of glucose transporters (GLUT)1 and 4; (b) lactate transporters (MCT)1 and 4; (c) cell cycle profile, and (d) protein levels of HIF-1α, total and phosphorylated AMPK (pAMPK). Mitochondrial functionality was evaluated by measuring O2 consumption in tumor cells using polarography and a Clark-type electrode. Tumor and non-transformed cells used both aerobic glycolysis and OXPHOS for obtaining energy. As of 48 h of culture, lactate levels ranged from (4.5-14 mM), thus forming a lactic environment. Lactic acidosis diminished GLUT1/GLUT4 expression and glucose consumption in A-549, but not in A-427 cells, and induced differential expression of HIF-1α, AMPK, and CS transcripts. A-427 cells increased pAMPK and HIF-1α levels and shifted their metabolism increasing OXPHOS; thus supporting cell growth. Conversely, A-549 cells increased HIF-1α protein levels, but did not activate AMPK and diminished OXPHOS. A-549 cells survived by arresting cells in G1-phase. Our findings show that lactic acidosis diminishes Warburg effect in tumor cells, but this change does not necessarily promote a shift to OXPHOS. Hence, lung adenocarcinomas show a differential metabolic response even when they are under the same microenvironmental conditions.

RevDate: 2020-06-30

Feng Y, Wu P, Fu W, et al (2020)

The Lotus japonicus Ubiquitin Ligase SIE3 Interacts With the Transcription Factor SIP1 and Forms a Homodimer.

Frontiers in plant science, 11:795.

The symbiosis receptor kinase SymRK plays an essential role in symbiotic signal transduction and nodule organogenesis. Several proteins bind to SymRK, but how the symbiosis signals are transduced from SymRK to downstream components remains elusive. We previously demonstrated that both SymRK interacting protein 1 (SIP1, an ARID-type DNA-binding protein) and SymRK interacting E3 ligase [SIE3, a RING (Really Interesting New Gene)-containing E3 ligase] interact with SymRK to regulate downstream cellular responses in Lotus japonicus during the legume-rhizobia symbiosis. Here, we show that SIE3 interacts with SIP1 in both yeast cells and Nicotiana benthamiana. SIE3 associated with itself and formed a homodimer. The cysteine 266 residue was found to be essential for SIE3 dimerization and for promoting nodulation in transgenic hairy roots of L. japonicus. Our findings provide a foundation for further investigating the regulatory mechanisms of the SymRK-mediated signaling pathway, as well as the biological function of E3 ligase dimerization in nodule organogenesis.

RevDate: 2020-06-29

Tominaga T, Yamaguchi K, Shigenobu S, et al (2020)

The effects of gibberellin on the expression of symbiosis-related genes in Paris-type arbuscular mycorrhizal symbiosis in Eustoma grandiflorum.

Plant signaling & behavior [Epub ahead of print].

Arbuscular mycorrhiza (AM) is a symbiotic interaction in terrestrial plants that is colonized by fungi in the Glomeromycotina. The morphological types of AM, including the Arum-type and Paris-type, are distinct, depending on the host plant species. A part of the regulatory pathways in Arum-type AM symbiosis has been revealed because most model plants form the Arum-type AM with a model AM fungus, Rhizophagus irregularis. Moreover, gibberellin (GA) is known to severely inhibit AM fungal colonization in Arum-type AM symbiosis. Recently, we showed that exogenous GA treatment significantly promoted AM fungal colonization in Paris-type AM symbiosis in Eustoma grandiflorum. In this study, we focused on the transcriptional changes in AM symbiosis-related genes in GA-treated E. grandiflorum. The expression levels of all examined E. grandiflorum genes were maintained or increased by GA treatment compared with those of the control treatment. Our new results suggest that signaling pathway(s) required for establishing AM symbiosis in E. grandiflorum may be distinct from the well-characterized pathway for that in model plants.

RevDate: 2020-06-29
CmpDate: 2020-06-29

Hazarika DJ, Gautom T, Parveen A, et al (2020)

Mechanism of interaction of an endofungal bacterium Serratia marcescens D1 with its host and non-host fungi.

PloS one, 15(4):e0224051.

Association of bacteria with fungi is a major area of research in infection biology, however, very few strains of bacteria have been reported that can invade and reside within fungal hyphae. Here, we report the characterization of an endofungal bacterium Serratia marcescens D1 from Mucor irregularis SS7 hyphae. Upon re-inoculation, colonization of the endobacterium S. marcescens D1 in the hyphae of Mucor irregularis SS7 was demonstrated using stereo microscopy. However, S. marcescens D1 failed to invade into the hyphae of the tested Ascomycetes (except Fusarium oxysporum) and Basidiomycetes. Remarkably, Serratia marcescens D1 could invade and spread over the culture of F. oxysporum that resulted in mycelial death. Prodigiosin, the red pigment produced by the Serratia marcescens D1, helps the bacterium to invade fungal hyphae as revealed by the increasing permeability in fungal cell membrane. On the other hand, genes encoding the type VI secretion system (T6SS) assembly protein TssJ and an outer membrane associated murein lipoprotein also showed significant up-regulation during the interaction process, suggesting the involvement of T6SS in the invasion process.

RevDate: 2020-06-30
CmpDate: 2020-06-30

Zhang T (2020)

DREPP in Nanodomains Regulates Microtubule Fragmentation during Symbiotic Infection.

The Plant cell, 32(5):1357-1358.

RevDate: 2020-06-30
CmpDate: 2020-06-30

Kaczmarek Ł, Roszkowska M, Poprawa I, et al (2020)

Integrative description of bisexual Paramacrobiotus experimentalis sp. nov. (Macrobiotidae) from republic of Madagascar (Africa) with microbiome analysis.

Molecular phylogenetics and evolution, 145:106730.

In a moss samples collected on Madagascar two populations of Paramacrobiotus experimentalis sp. nov. were found. Paramacrobiotus experimentalis sp. nov. with the presence of a microplacoid and areolatus type of eggs is similar to Pam. danielae, Pam. garynahi, Pam. hapukuensis, Pam. peteri, Pam. rioplatensis and Pam. savai, but it differs from them by some morphological and morphometric characters of the eggs. The p-distance between two COI haplotypes of Pam. experimentalis sp. nov. was 0.17%. In turn, the ranges of uncorrected genetic p-distances of all Paramacrobiotus species available in GenBank was from 18.27% (for Pam. lachowskae) to 25.26% (for Pam. arduus) with an average distance of 20.67%. We also found that Pam. experimentalis sp. nov. is bisexual. This observation was congruent on three levels: (i) morphological - specimen size dimorphism; (ii) structural (primary sexual characteristics) - females have an unpaired ovary while males have an unpaired testis and (iii) molecular - heterozygous and homozygous strains of the ITS-2 marker. Although symbiotic associations of hosts with bacteria (including endosymbiotic bacteria) are common in nature and these interactions exert various effects on the evolution, biology and reproductive ecology of hosts, there is still very little information on the bacterial community associated with tardigrades. To fill this gap and characterise the bacterial community of Pam. experimentalis sp. nov. populations and microbiome of its microhabitat, high throughput sequencing of the V3-V4 hypervariable regions in the bacterial 16S rRNA gene fragment was performed. The obtained 16S rRNA gene sequences ranged from 92,665 to 131,163. In total, 135 operational taxonomic units (OTUs) were identified across the rarefied dataset. Overall, both Pam. experimentalis sp. nov. populations were dominated by OTUs ascribed to the phylum Proteobacteria (89-92%) and Firmicutes (6-7%). In the case of samples from tardigrades' laboratory habitat, the most abundant bacterial phylum was Proteobacteria (51-90%) and Bacteroides (9-48%). In all compared microbiome profiles, only 16 of 137 OTUs were shared. We found also significant differences in beta diversity between the partly species-specific microbiome of Pam. experimentalis sp. nov. and its culturing environment. Two OTUs belonging to a putative bacterial endosymbiont were identified - Rickettsiales and Polynucleobacter. We also demonstrated that each bacterial community was rich in genes involved in membrane transport, amino acid metabolism, and carbohydrate metabolism.

RevDate: 2020-06-29
CmpDate: 2020-06-29

Jeudy S, Bertaux L, Alempic JM, et al (2020)

Exploration of the propagation of transpovirons within Mimiviridae reveals a unique example of commensalism in the viral world.

The ISME journal, 14(3):727-739.

Acanthamoeba-infecting Mimiviridae are giant viruses with dsDNA genome up to 1.5 Mb. They build viral factories in the host cytoplasm in which the nuclear-like virus-encoded functions take place. They are themselves the target of infections by 20-kb-dsDNA virophages, replicating in the giant virus factories and can also be found associated with 7-kb-DNA episomes, dubbed transpovirons. Here we isolated a virophage (Zamilon vitis) and two transpovirons respectively associated to B- and C-clade mimiviruses. We found that the virophage could transfer each transpoviron provided the host viruses were devoid of a resident transpoviron (permissive effect). If not, only the resident transpoviron originally isolated from the corresponding virus was replicated and propagated within the virophage progeny (dominance effect). Although B- and C-clade viruses devoid of transpoviron could replicate each transpoviron, they did it with a lower efficiency across clades, suggesting an ongoing process of adaptive co-evolution. We analysed the proteomes of host viruses and virophage particles in search of proteins involved in this adaptation process. This study also highlights a unique example of intricate commensalism in the viral world, where the transpoviron uses the virophage to propagate and where the Zamilon virophage and the transpoviron depend on the giant virus to replicate, without affecting its infectious cycle.

RevDate: 2020-06-29
CmpDate: 2020-06-29

Ju JF, Bing XL, Zhao DS, et al (2020)

Wolbachia supplement biotin and riboflavin to enhance reproduction in planthoppers.

The ISME journal, 14(3):676-687.

Symbiont-mediated nutritional mutualisms can contribute to the host fitness of insects, especially for those that feed exclusively on nutritionally unbalanced diets. Here, we elucidate the importance of B group vitamins in the association of endosymbiotic bacteria Wolbachia with two plant-sap feeding insects, the small brown planthopper, Laodelphax striatellus (Fallén), and the brown planthopper, Nilaparvata lugens (Stål). Infected planthoppers of both species laid more eggs than uninfected planthoppers, while the experimental transfer of Wolbachia into uninfected lines of one planthopper species rescued this fecundity deficit. The genomic analysis showed that Wolbachia strains from the two planthopper species encoded complete biosynthesis operons for biotin and riboflavin, while a metabolic analysis revealed that Wolbachia-infected planthoppers of both species had higher titers of biotin and riboflavin. Furthermore, experimental supplementation of food with a mixture of biotin and riboflavin recovered the fecundity deficit of Wolbachia-uninfected planthoppers. In addition, comparative genomic analysis suggested that the riboflavin synthesis genes are conserved among Wolbachia supergroups. Biotin operons are rare in Wolbachia, and those described share a recent ancestor that may have been horizontally transferred from Cardinium bacteria. Our research demonstrates a type of mutualism that involves a facultative interaction between Wolbachia and plant-sap feeding insects involving vitamin Bs.

RevDate: 2020-06-29
CmpDate: 2020-06-29

Ansorge R, Romano S, Sayavedra L, et al (2019)

Functional diversity enables multiple symbiont strains to coexist in deep-sea mussels.

Nature microbiology, 4(12):2487-2497.

Genetic diversity of closely related free-living microorganisms is widespread and underpins ecosystem functioning, but most evolutionary theories predict that it destabilizes intimate mutualisms. Accordingly, strain diversity is assumed to be highly restricted in intracellular bacteria associated with animals. Here, we sequenced metagenomes and metatranscriptomes of 18 Bathymodiolus mussel individuals from four species, covering their known distribution range at deep-sea hydrothermal vents in the Atlantic. We show that as many as 16 strains of intracellular, sulfur-oxidizing symbionts coexist in individual Bathymodiolus mussels. Co-occurring symbiont strains differed extensively in key functions, such as the use of energy and nutrient sources, electron acceptors and viral defence mechanisms. Most strain-specific genes were expressed, highlighting their potential to affect fitness. We show that fine-scale diversity is pervasive in Bathymodiolus sulfur-oxidizing symbionts, and hypothesize that it may be widespread in low-cost symbioses where the environment, rather than the host, feeds the symbionts.

RevDate: 2020-06-30
CmpDate: 2020-06-30

Watanabe T, Suzuki N, Tomonaga K, et al (2019)

Neo-virology: The raison d'etre of viruses.

Virus research, 274:197751.

Given that approximately 1031 virus particles exist on Earth and all of them are parasitic in living organisms, it is not hard to imagine how virus infection might affect the physiology of hosts and their ecosystems. However, traditional virology research tends to focus on viral pathogenicity or the individual pathogenic viruses; hence, the significance of viruses and viral-mediated processes in the global ecosystem has been poorly understood. To identify the previously unrecognized "raison d'etre of viruses" in nature, we established a research community, designated as the 'Neo-virology' consortium. In this consortium, we define a virus as a component of the global ecosystem and our aim is to elucidate its key roles in host organisms, that is, the intra-host ecosystem.

RevDate: 2020-06-29
CmpDate: 2020-06-29

Yu K, Pieterse CMJ, Bakker PAHM, et al (2019)

Beneficial microbes going underground of root immunity.

Plant, cell & environment, 42(10):2860-2870.

Plant roots interact with an enormous diversity of commensal, mutualistic, and pathogenic microbes, which poses a big challenge to roots to distinguish beneficial microbes from harmful ones. Plants can effectively ward off pathogens following immune recognition of conserved microbe-associated molecular patterns (MAMPs). However, such immune elicitors are essentially not different from those of neutral and beneficial microbes that are abundantly present in the root microbiome. Recent studies indicate that the plant immune system plays an active role in influencing rhizosphere microbiome composition. Moreover, it has become increasingly clear that root-invading beneficial microbes, including rhizobia and arbuscular mycorrhiza, evade or suppress host immunity to establish a mutualistic relationship with their host. Evidence is accumulating that many free-living rhizosphere microbiota members can suppress root immune responses, highlighting root immune suppression as an important function of the root microbiome. Thus, the gate keeping functions of the plant immune system are not restricted to warding off root-invading pathogens but also extend to rhizosphere microbiota, likely to promote colonization by beneficial microbes and prevent growth-defense tradeoffs triggered by the MAMP-rich rhizosphere environment.

RevDate: 2020-06-29
CmpDate: 2020-06-29

Rees DJ, Noever C, Finucci B, et al (2019)

De novo innovation allows shark parasitism and global expansion of the barnacle Anelasma squalicola.

Current biology : CB, 29(12):R562-R563.

The barnacle Anelasma squalicola is a marine epibiont found on members of the species-rich, deep-sea lantern shark family Etmopteridae (Figure 1A) but is unlike any other epibiotic thoracian barnacles [1]. While many barnacle species are associated with various marine animals including turtles and whales, with the exception of Anelasma these all retain a filter-feeding lifestyle and have a commensal relationship with their host; despite often being deeply embedded in the dermis, no other species has been reported as feeding on its host. Although Anelasma is fully equipped with cirri (thoracic appendages), these are no longer used for filter feeding [1]. Instead, Anelasma embeds a stalk with root-like structures into the flesh of the shark (Figure S1C in Supplemental Information, published with this article online) that it uses to parasitize its host. Here, we show that specimens of Anelasma sampled from all over the world show very little genetic differentiation, suggesting that this innovation coincided with a rapid worldwide expansion.

RevDate: 2020-06-30
CmpDate: 2020-06-30

Hols P, Ledesma-García L, Gabant P, et al (2019)

Mobilization of Microbiota Commensals and Their Bacteriocins for Therapeutics.

Trends in microbiology, 27(8):690-702.

With the specter of resurgence of pathogens due to the propagation of antibiotic-resistance genes, innovative antimicrobial strategies are needed. In this review, we summarize the beneficial aspects of bacteriocins, a set of miscellaneous peptide-based bacterium killers, compared with classical antibiotics, and emphasize their use in cocktails to curb the emergence of new resistance. We highlight that their prey spectrum, their molecular malleability, and their multiple modes of production might lead to specific and personalized treatments to prevent systemic disorders. Complementarily, we discuss how we might exploit prevailing bacterial commensals, such as Streptococcus salivarius, and deliberately mobilize their bacteriocin arsenal 'on site' to cure multiresistant infections or finely reshape the endogenous microbiota for prophylaxis purposes.

RevDate: 2020-06-30
CmpDate: 2020-06-30

Mazel-Sanchez B, Yildiz S, M Schmolke (2019)

Ménage à trois: Virus, Host, and Microbiota in Experimental Infection Models.

Trends in microbiology, 27(5):440-452.

Infections of mammals with pathogenic viruses occur mostly in the polymicrobial environment of mucosal surfaces or the skin. In recent years our understanding of immune modulation by the commensal microbiota has increased dramatically. The microbiota is today accepted as the prime educator and maintainer of innate and adaptive immune functions. It became further apparent that some viral pathogens profit from the presence of commensal bacteria and their metabolites, especially in the intestinal tract. We further learned that the composition and abundance of the microbiota can change as a consequence of acute and chronic viral infections. Here we discuss recent developments in our understanding of the triangular relationship of virus, host, and microbiota under experimental infection settings.

RevDate: 2020-06-27

Alemneh AA, Zhou Y, Ryder MH, et al (2020)

Mechanisms in plant growth-promoting rhizobacteria that enhance the legume-rhizobial symbiosis.

Journal of applied microbiology [Epub ahead of print].

Nitrogen fixation is an important biological process in terrestrial ecosystems and for global crop production. Legume nodulation and N2 fixation has been improved using nodule-enhancing rhizobacteria (NER) under both regular and stressed conditions. The positive effect of NER on legume-rhizobia symbiosis can be facilitated by plant growth-promoting mechanisms, some of which remain to be identified. NER that produce aminocyclopropane-1-carboxylic acid (ACC) deaminase and indoleacetic acid (IAA) enhance the legume-rhizobia symbiosis through (a) enhancing the nodule induction, (b) improving the competitiveness of rhizobia for nodulation, (c) prolonging functional nodules by suppressing nodule senescence and (d) upregulating genes associated with legume-rhizobia symbiosis. The means by which these processes enhance the legume-rhizobia symbiosis is the focus of this review. Through a better understanding of the mechanisms by which PGPR operate, and how they can be altered, will provide an opportunity to enhance legume rhizobial interactions, to provide new advances in plant growth promotion and N2 fixation.

RevDate: 2020-06-27

Sproles AE, Oakley CA, Krueger T, et al (2020)

Sub-cellular imaging shows reduced photosynthetic carbon and increased nitrogen assimilation by the non-native endosymbiont Durusdinium trenchii in the model cnidarian Aiptasia.

Environmental microbiology [Epub ahead of print].

Hosting different symbiont species can affect inter-partner nutritional fluxes within the cnidarian-dinoflagellate symbiosis. Using nanoscale secondary ion mass spectrometry (NanoSIMS), we measured the spatial incorporation of photosynthetically-fixed 13 C and heterotrophically-derived 15 N into host and symbiont cells of the model symbiotic cnidarian Aiptasia (Exaiptasia pallida) when colonised with its native symbiont Breviolum minutum or the non-native Durusdinium trenchii. B. minutum exhibited high photosynthetic carbon assimilation per cell and translocation to host tissue throughout symbiosis establishment, while D. trenchii assimilated significantly less carbon, but obtained more host nitrogen. These findings suggest that D. trenchii has less potential to provide photosynthetically-fixed carbon to the host despite obtaining considerable amounts of heterotrophically-derived nitrogen. These sub-cellular events help explain previous observations that demonstrate differential effects of D. trenchii compared to B. minutum on the host transcriptome, proteome, metabolome, and host growth and asexual reproduction. Together, these differential effects suggest that the non-native host-symbiont pairing is sub-optimal with respect to the host's nutritional benefits under normal environmental conditions. This contributes to our understanding of the ways in which metabolic integration impacts the benefits of a symbiotic association, and the potential evolution of novel host-symbiont pairings. This article is protected by copyright. All rights reserved.

RevDate: 2020-06-27

Regaiolo A, Dominelli N, Andresen K, et al (2020)

The biocontrol agent and insect pathogen Photorhabdus luminescens interacts with plant roots.

Applied and environmental microbiology pii:AEM.00891-20 [Epub ahead of print].

Sustainable agriculture techniques are rising to improve pest management and environmental safety: biological control agents are used to enhance disease resistance and abiotic stress tolerance in crops. Here we investigated the capacity of Photorhabdus luminescens secondary variant to react to plant root exudates and its behaviour towards microorganisms in the rhizosphere. P. luminescens is known to live in symbiosis with entomopathogenic nematodes (EPNs) and to be highly pathogenic towards insects. The P. luminescens-EPNs relationship has been widely studied and used as a biological control agent, however, not much attention has been given on a putative lifestyle of P. luminescens in the rhizosphere. We performed transcriptome analysis to show how P. luminescens responds to plant root exudates. The analysis highlighted genes involved in chitin degradation, biofilm regulation, flagella formation and type VI secretion system. Furthermore, we provide evidence that P. luminescens can inhibit growth of phytopathogenic fungi. Finally, we demonstrated a specific interaction of P. luminescens with plant roots. Understanding the role and the function of this bacterium in the rhizosphere might accelerate the progress in biocontrol manipulation and elucidate the peculiar mechanisms adopted by plant growth-promoting rhizobacteria in plant roots interaction.Importance of the study Insect pathogenic Photorhabdus luminescens bacteria are widely used in biocontrol strategies against pests. Very little is known about the life of these bacteria in the rhizosphere. Here we show that P. luminescens can specifically react to and interact with plant roots. Understanding the adaptation of P. luminescens in the rhizosphere is highly important for the biotechnological application of entomopathogenic bacteria and could improve future sustainable pest management in agriculture.

RevDate: 2020-06-27

Kang W, Jiang Z, Chen Y, et al (2020)

Plant transcriptome analysis reveals specific molecular interactions between alfalfa and its rhizobial symbionts below the species level.

BMC plant biology, 20(1):293 pii:10.1186/s12870-020-02503-3.

BACKGROUND: Leguminous plants alter patterns of gene expression in response to symbiotic colonization and infection by their cognate rhizobial bacteria, but the extent of the transcriptomic response has rarely been examined below the species level. Here we describe the identification of 12 rhizobial biotypes of Ensifer meliloti, which form nitrogen-fixing nodules in the roots of alfalfa (Medicago sativa L.), followed by a comparative RNA-seq analysis of four alfalfa cultivars each inoculated with two E. meliloti strains varying in symbiotic performance and phylogenetic relatedness.

RESULTS: Rhizobial biotypes were identified on the basis of their symbiotic performance, particularly shoot dry weight. Differentially expressed genes (DEGs) and metabolic pathways were determined by comparing the RNA-seq data with that of the uninoculated control plant. Significant differences were found between DEGs generated in each cultivar with the inoculation of two rhizobial strains in comparison (P < 0.01). A total of 8111 genes was differentially expressed, representing ~ 17.1% of the M. sativa genome. The proportion of DEGs ranges from 0.5 to 12.2% for each alfalfa cultivar. Interestingly, genes with predicted roles in flavonoid biosynthesis and plant-pathogen interaction (NBS-LRR) were identified as the most significant DEGs. Other DEGs include Medsa002106 and genes encoding nodulins and NCR peptides whose expression is specifically induced during the development of nitrogen-fixing nodules. More importantly, strong significant positive correlations were observed between plant transcriptomes (DEGs and KEGG pathways) and phylogenetic distances between the two rhizobial inoculants.

CONCLUSIONS: Alfalfa expresses significantly distinct sets of genes in response to infection by different rhizobial strains at the below-species levels (i.e. biotype or strain). Candidate genes underlying the specific interactions include Medsa002106 and those encoding nodulins and NCR peptides and proteins in the NBS-LRR family.

RevDate: 2020-06-26

Fang J, Liu M, Zhang S, et al (2020)

Complex chemical signaling interactions: A bark beetle-fungus symbiotic system and host/non-host trees.

Journal of experimental botany pii:5863268 [Epub ahead of print].

The symbiosis between the bark beetle (Ips subelongatus) and its fungal symbiont (Endoconidiophora fujiensis) poses a serious threat to larch forests. However, the signaling pathways between these symbiotic partners and their host/non-host trees are not fully understood. Inoculation of the host larch (Larix principis-rupprechtii) with two strains of E. fujiensis induced a rapid and long-term release of monoterpenes. Althouh the fungi had a level of tolerance to hese compounds, many monoterpenes inhibited fungal culture growth. Moreover, monoterpenes with stronger inhibitory effects on fungal growth exhibited weaker synergistic effects on the attraction of I. subelongatus to aggregation pheromone. Surprisingly, individual isomers of aggregation pheromone components promoted fungal symbiont growth in a culture medium. Non-host volatiles (NHVs) were tested and shown to completely inhibit the growth of fungal symbionts in culture but had no effects on beetle responses to aggregation pheromone with the exception of (Z)-3-hexen-1-ol. These results reveal convergence and mutualism patterns in the evolution of I. subelongatus and E. fujiensis with respect to host tree volatiles but not in response to NHVs. Ultimately, we put forward a hypothesis that host plants are ecological and evolutionary determinants of bark beetle-fungus symbioses in terms of their complex signaling interactions.

RevDate: 2020-06-26

Jiménez-Guerrero I, Acosta-Jurado S, Medina C, et al (2020)

The Sinorhizobium fredii HH103 Type III secretion system effector NopC blocks nodulation with Lotus japonicus Gifu.

Journal of experimental botany pii:5863328 [Epub ahead of print].

The broad host-range bacterium Sinorhizobium fredii HH103 cannot nodulate the model legume Lotus japonicus Gifu. This bacterium possesses a Type III secretion system (T3SS), a specialized secretion apparatus used to deliver effector proteins (T3E) into the host cell cytosol to alter host signaling and/or suppress host defence responses to promote infection. However, some of these T3E are recognized by specific plant receptors and hence trigger a strong defence response to block infection. In rhizobia, T3E are involved in nodulation efficiency, host-range determination and, in some cases, directly activate host symbiosis signalling in a Nod factor-independent manner. In this work, we show that HH103 RifR T3SS mutants, unable to secrete T3E, gain nodulation with L. japonicus Gifu through infection threads (IT), suggesting that plant recognition of a T3E could block the infection process. To identify the T3E involved, we performed nodulation assays with a collection of mutants affected in secretion of each T3E identified in HH103 RifR so far. The nopC mutant could infect L. japonicus Gifu by IT invasion and switch the infection mechanism in L. burttii from intercellular infection to IT formation. L. japonicus gene expression analysis indicated that the infection-blocking event occurs at early stages of the symbiosis.

RevDate: 2020-06-26

Montenegro F, S Indraccolo (2020)

Metabolism in the Tumor Microenvironment.

Advances in experimental medicine and biology, 1263:1-11.

From a general perspective, in the context of solid tumors, we can distinguish metabolic alterations of cancer cells from those of the stroma. These two components interact with each other and with the extracellular matrix (ECM), and these interactions can take the form of either metabolic competition or metabolic symbiosis. The aim of this chapter is to overview the canonical metabolic alterations of tumor and stroma cells and to present specific examples of metabolic competition and symbiosis. We will also discuss the complexity and plasticity of metabolism, which pose indeed a serious threat to our ability to target selective metabolic features of tumor microenvironment with drugs. Finally, we will highlight some limitations of state-of-the-art techniques used to study tumor metabolism and propose some innovative solutions to investigate the clinical relevance of metabolic alterations for patient management and treatment.

RevDate: 2020-06-26

Doerner P (2020)

Extreme environments: crucibles of potent abiotic stress tolerance.

Journal of experimental botany, 71(13):3761-3764.

RevDate: 2020-06-26

Wang S, Chen A, Xie K, et al (2020)

Functional analysis of the OsNPF4.5 nitrate transporter reveals a conserved mycorrhizal pathway of nitrogen acquisition in plants.

Proceedings of the National Academy of Sciences of the United States of America pii:2000926117 [Epub ahead of print].

Low availability of nitrogen (N) is often a major limiting factor to crop yield in most nutrient-poor soils. Arbuscular mycorrhizal (AM) fungi are beneficial symbionts of most land plants that enhance plant nutrient uptake, particularly of phosphate. A growing number of reports point to the substantially increased N accumulation in many mycorrhizal plants; however, the contribution of AM symbiosis to plant N nutrition and the mechanisms underlying the AM-mediated N acquisition are still in the early stages of being understood. Here, we report that inoculation with AM fungus Rhizophagus irregularis remarkably promoted rice (Oryza sativa) growth and N acquisition, and about 42% of the overall N acquired by rice roots could be delivered via the symbiotic route under N-NO3- supply condition. Mycorrhizal colonization strongly induced expression of the putative nitrate transporter gene OsNPF4.5 in rice roots, and its orthologs ZmNPF4.5 in Zea mays and SbNPF4.5 in Sorghum bicolor OsNPF4.5 is exclusively expressed in the cells containing arbuscules and displayed a low-affinity NO3- transport activity when expressed in Xenopus laevis oocytes. Moreover, knockout of OsNPF4.5 resulted in a 45% decrease in symbiotic N uptake and a significant reduction in arbuscule incidence when NO3- was supplied as an N source. Based on our results, we propose that the NPF4.5 plays a key role in mycorrhizal NO3- acquisition, a symbiotic N uptake route that might be highly conserved in gramineous species.

RevDate: 2020-06-26

Kadam SB, Pable AA, VT Barvkar (2020)

Mycorrhiza induced resistance (MIR): a defence developed through synergistic engagement of phytohormones, metabolites and rhizosphere.

Functional plant biology : FPB pii:FP20035 [Epub ahead of print].

Plants get phosphorus, water and other soil nutrients at the cost of sugar through mycorrhizal symbiotic association. A common mycorrhizal network (CMN) - a dense network of mycorrhizal hyphae - provides a passage for exchange of chemicals and signals between the plants sharing CMN. Mycorrhisation impact plants at hormonal, physiological and metabolic level and successful symbiosis also regulates ecology of the plant rhizosphere. Apart from nutritional benefits, mycorrhisation provides an induced resistance to the plants known as mycorrhiza induced resistance (MIR). MIR is effective against soil as well as foliar pathogens and pest insects. In this review, molecular mechanisms underlying MIR such as role of phytohormones, their cross talk and priming effect are discussed. Evidence of MIR against economically important pathogens and pest insects in different plants is summarised. Mycorrhiza induces many plant secondary metabolites, many of which have a role in plant defence. Involvement of these secondary metabolites in mycorrhisation and their putative role in MIR are further reviewed. Controversies about MIR are also briefly discussed in order to provide insights on the scope for research about MIR. We have further extended our review with an open ended discussion about the possibilities for transgenerational MIR.

RevDate: 2020-06-26
CmpDate: 2020-06-26

Shao SC, Wang QX, Beng KC, et al (2020)

Fungi isolated from host protocorms accelerate symbiotic seed germination in an endangered orchid species (Dendrobium chrysotoxum) from southern China.

Mycorrhiza, 30(4):529-539.

To ensure long-term survival of epiphytic orchids through active reintroduction, more research on critical life cycle stages such as seed germination and seedling establishment are needed. In this study, we used in vitro germination experiments to investigate the role of mycorrhizal fungi in determining seed germination and growth in the endangered epiphytic orchid species, Dendrobium chrysotoxum. Symbiotic seed germination experiments were conducted for 90 days under different light conditions with fungal strains isolated from protocorms of D. chrysotoxum and three sister species. Molecular analyses showed that five strains belonged to the typical orchid mycorrhizal family Tulasnellaceae, whereas the other two strains belonged to the Sebacinaceae and the genus Coprinellus. Fungal inoculation, light conditions, and their interaction had a significant effect on protocorm formation and seedling development. Three fungal isolates, including two from D. chrysotoxum and one from D. catenatum, significantly stimulated protocorm formation and seedling development under light conditions. However, fungi isolated from host protocorms (GC-14 and GC-15) produced the highest number of seedlings after 50 days (49.5 ± 8.5%, 51.3 ± 9.0%, respectively), while the fungus isolated from D. catenatum protocorms produced the maximum number of seedlings only after 90 days (48.7 ± 16.1%). To conclude, this study has shown that light conditions and the identity of fungi had a strong effect on in vitro seed germination and seedling formation in an epiphytic orchid, with fungi isolated from host protocorms leading to accelerated germination and seedling formation. Therefore, fungal source should be taken into account when using seeds and compatible fungi for seedling propagation and in situ reintroduction.

RevDate: 2020-06-26
CmpDate: 2020-06-26

Marqués-Gálvez JE, Morte A, A Navarro-Ródenas (2020)

Spring stomatal response to vapor pressure deficit as a marker for desert truffle fruiting.

Mycorrhiza, 30(4):503-512.

The cultivation of desert truffle Terfezia claveryi using Helianthemum almeriense as a host plant has recently become a solid alternative crop in the Mediterranean region due to its adaptation to arid and semiarid ecosystems, which are expected to increase during the following years because of climate change. However, management models are still being developed in order to improve and stabilize the production, which varies greatly from one year to another. According to gatherers and farmers, one of the key factors for desert truffle production is the plant phenology in spring, which, in turn, depends on environmental conditions. In this manuscript, we have characterized the physiological, morphological, and molecular responses of the mycorrhizal plants in spring, coinciding with the fructification period of the plant and fungal species. Thanks to this characterization, a sigmoidal relationship between stomatal conductance and vapor pressure deficit (VPD) was found, which can be used as a marker of plant phenological switch. In order to confirm that this phenology status is related to desert truffle fructification, this marker has been successfully correlated to total truffle production. The results of this manuscript suppose a big step forward that will help to develop management models for the desert truffle crop.

RevDate: 2020-06-26
CmpDate: 2020-06-26

Aguilar-Rodríguez J, Fares MA, A Wagner (2019)

Chaperonin overproduction and metabolic erosion caused by mutation accumulation in Escherichia coli.

FEMS microbiology letters, 366(10):.

Bacterial cells adapting to a constant environment tend to accumulate mutations in portions of their genome that are not maintained by selection. This process has been observed in bacteria evolving under strong genetic drift, and especially in bacterial endosymbionts of insects. Here, we study this process in hypermutable Escherichia coli populations evolved through 250 single-cell bottlenecks on solid rich medium in a mutation accumulation experiment that emulates the evolution of bacterial endosymbionts. Using phenotype microarrays monitoring metabolic activity in 95 environments distinguished by their carbon sources, we observe how mutation accumulation has decreased the ability of cells to metabolize most carbon sources. We study if the chaperonin GroEL, which is naturally overproduced in bacterial endosymbionts, can ameliorate the process of metabolic erosion, because of its known ability to buffer destabilizing mutations in metabolic enzymes. Our results indicate that GroEL can slow down the negative phenotypic consequences of genome decay in some environments.

RevDate: 2020-06-26
CmpDate: 2020-06-26

De Filippo C, Di Paola M, Giani T, et al (2019)

Gut microbiota in children and altered profiles in juvenile idiopathic arthritis.

Journal of autoimmunity, 98:1-12.

Microbial diversity plays a key role in the maintenance of intestinal homeostasis and in the development of the immune system in the gut mucosa. Maybe one of the most important function of our gut microbiota is the immune system education, in particular the discrimination of friends from foes that occurs during childhood. In addition to bacterial antigens, several metabolites of microbial origin have a crucial role in training of the immune system, such as Short Chain Fatty Acids (SCFAs). There are many evidences on the role of the gut microbiota in rheumatic diseases, in particular modifications of microbiota composition causing dysbiosis that, in turn, can induce gut permeability, and thus immunological imbalance and trigger inflammation. In particular, immune cells can reach extra-intestinal sites, such as joints and trigger local inflammation. Childhood is a crucial period of life for development and evolution of the gut microbiota, especially for the acquisition of fundamental functions such as immunotolerance of commensal microorganisms. For this reason, gut dysbiosis is gaining interest as a potential pathogenetic factor for Juvenile Idiopathic Arthritis (JIA). Here we summarized the studies conducted on JIA patients in which a pro-arthritogenic microbial profiles has been observed; this, together with a depletion of microbial biodiversity, clearly distinguish patients' from healthy subjects' microbiota. Further studies are however needed to better clarify the role of microbiota in JIA pathogenesis.

RevDate: 2020-06-25

Ho LH, Lee YI, Hsieh SY, et al (2020)

GeSUT4 mediates sucrose import at the symbiotic interface for carbon allocation of heterotrophic Gastrodia elata (Orchidaceae).

Plant, cell & environment [Epub ahead of print].

Gastrodia elata, a fully mycoheterotrophic orchid without photosynthetic ability, only grows symbiotically with the fungus Armillaria. The mechanism of carbon distribution in this mycoheterotrophy is unknown. We detected high sucrose concentrations in all stages of Gastrodia tubers, suggesting sucrose may be the major sugar transported between fungus and orchid. Thick symplasm-isolated wall interfaces in colonized and adjacent large cells implied involvement of sucrose importers. Two sucrose transporter (SUT)-like genes, GeSUT4 and GeSUT3, were identified that are highly expressed in young Armillaria-colonized tubers. Yeast complementation and isotope tracer experiments confirmed that GeSUT4 functioned as a high-affinity sucrose-specific proton-dependent importer. Plasma- membrane/tonoplast localization of GeSUT4-GFP fusions, and high RNA expression of GeSUT4 in symbiotic and large cells indicated that GeSUT4 likely functions in active sucrose transport for intercellular allocation and intracellular homeostasis. Transgenic Arabidopsis overexpressing GeSUT4 had larger leaves but were sensitive to excess sucrose and roots were colonized with fewer mutualistic Bacillus, supporting the role of GeSUT4 in regulating sugar allocation. This is not only the first documented carbon import system in a mycoheterotrophic interaction, but also highlights the evolutionary importance of sucrose transporters for regulation of carbon flow in all types of plant-microbe interactions. This article is protected by copyright. All rights reserved.

RevDate: 2020-06-25

Signorelli S, Sainz M, Tabares-da Rosa S, et al (2020)

The Role of Nitric Oxide in Nitrogen Fixation by Legumes.

Frontiers in plant science, 11:521.

The legume-rhizobia symbiosis is an important process in agriculture because it allows the biological nitrogen fixation (BNF) which contributes to increasing the levels of nitrogen in the soil. Nitric oxide (⋅NO) is a small free radical molecule having diverse signaling roles in plants. Here we present and discuss evidence showing the role of ⋅NO during different stages of the legume-rhizobia interaction such as recognition, infection, nodule development, and nodule senescence. Although the mechanisms by which ⋅NO modulates this interaction are not fully understood, we discuss potential mechanisms including its interaction with cytokinin, auxin, and abscisic acid signaling pathways. In matures nodules, a more active metabolism of ⋅NO has been reported and both the plant and rhizobia participate in ⋅NO production and scavenging. Although ⋅NO has been shown to induce the expression of genes coding for NITROGENASE, controlling the levels of ⋅NO in mature nodules seems to be crucial as ⋅NO was shown to be a potent inhibitor of NITROGENASE activity, to induce nodule senescence, and reduce nitrogen assimilation. In this sense, LEGHEMOGLOBINS (Lbs) were shown to play an important role in the scavenging of ⋅NO and reactive nitrogen species (RNS), potentially more relevant in senescent nodules. Even though ⋅NO can reduce NITROGENASE activity, most reports have linked ⋅NO to positive effects on BNF. This can relate mainly to the regulation of the spatiotemporal distribution of ⋅NO which favors some effects over others. Another plausible explanation for this observation is that the negative effect of ⋅NO requires its direct interaction with NITROGENASE, whereas the positive effect of ⋅NO is related to its signaling function, which results in an amplifier effect. In the near future, it would be interesting to explore the role of environmental stress-induced ⋅NO in BNF.

RevDate: 2020-06-25

Mateos M, Martinez Montoya H, Lanzavecchia SB, et al (2020)

Wolbachia pipientis Associated With Tephritid Fruit Fly Pests: From Basic Research to Applications.

Frontiers in microbiology, 11:1080.

Members of the true fruit flies (family Tephritidae) are among the most serious agricultural pests worldwide, whose control and management demands large and costly international efforts. The need for cost-effective and environmentally friendly integrated pest management (IPM) has led to the development and implementation of autocidal control strategies. These approaches include the widely used sterile insect technique and the incompatible insect technique (IIT). IIT relies on maternally transmitted bacteria (namely Wolbachia) to cause a conditional sterility in crosses between released mass-reared Wolbachia-infected males and wild females, which are either uninfected or infected with a different Wolbachia strain (i.e., cytoplasmic incompatibility; CI). Herein, we review the current state of knowledge on Wolbachia-tephritid interactions including infection prevalence in wild populations, phenotypic consequences, and their impact on life history traits. Numerous pest tephritid species are reported to harbor Wolbachia infections, with a subset exhibiting high prevalence. The phenotypic effects of Wolbachia have been assessed in very few tephritid species, due in part to the difficulty of manipulating Wolbachia infection (removal or transinfection). Based on recent methodological advances (high-throughput DNA sequencing) and breakthroughs concerning the mechanistic basis of CI, we suggest research avenues that could accelerate generation of necessary knowledge for the potential use of Wolbachia-based IIT in area-wide integrated pest management (AW-IPM) strategies for the population control of tephritid pests.

RevDate: 2020-06-25

Menéndez E, Flores-Félix JD, Ramírez-Bahena MH, et al (2020)

Genome Analysis of Endobacterium cerealis, a Novel Genus and Species Isolated from Zea mays Roots in North Spain.

Microorganisms, 8(6): pii:microorganisms8060939.

In the present work, we analyse the genomic and phenotypic characteristics of a strain named RZME27T isolated from roots of a Zea mays plant grown in Spain. The phylogenetic analyses of 16S rRNA gene and whole genome sequences showed that the strain RZME27T clustered with the type strains of Neorhizobium galegae and Pseudorhizobium pelagicum from the family Rhizobiaceae. This family encompasses several genera establishing symbiosis with legumes, but the genes involved in nodulation and nitrogen fixation are absent in its genome. Nevertheless, genes related to plant colonization, such as those involved in motility, chemotaxis, quorum sensing, exopolysaccharide biosynthesis and hydrolytic enzymes production were found. The comparative pangenomic analyses showed that 78 protein clusters present in the strain RZME27T were not found in the type strains of its closest relatives N. galegae and P. pelagicum. The calculated average nucleotide identity (ANI) values between the strain RZME27T and the type strains of N. galegae and P. pelagicum were 75.61% and 75.1%, respectively, similar or lower than those found for other genera from family Rhizobiaceae. Several phenotypic differences were also found, highlighting the absence of the fatty acid C19:0 cyclo ω8c and propionate assimilation. These results support the definition of a novel genus and species named Endobacterium cerealis gen. nov. sp. nov. whose type strain is RZME27T.

RevDate: 2020-06-25

Miozzi L, Vaira AM, Brilli F, et al (2020)

Arbuscular Mycorrhizal Symbiosis Primes Tolerance to Cucumber Mosaic Virus in Tomato.

Viruses, 12(6): pii:v12060675.

Tomato plants can establish symbiotic interactions with arbuscular mycorrhizal fungi (AMF) able to promote plant nutrition and prime systemic plant defenses against pathogens attack; the mechanism involved is known as mycorrhiza-induced resistance (MIR). However, studies on the effect of AMF on viral infection, still limited and not conclusive, indicate that AMF colonization may have a detrimental effect on plant defenses against viruses, so that the term "mycorrhiza-induced susceptibility" (MIS) has been proposed for these cases. To expand the case studies to a not yet tested viral family, that is, Bromoviridae, we investigated the effect of the colonization by the AMF Funneliformis mosseae on cucumber mosaic virus (CMV) infection in tomato by phenotypic, physiological, biochemical, and transcriptional analyses. Our results showed that the establishment of a functional AM symbiosis is able to limit symptoms development. Physiological and transcriptomic data highlighted that AMF mitigates the drastic downregulation of photosynthesis-related genes and the reduction of photosynthetic CO2 assimilation rate caused by CMV infection. In parallel, an increase of salicylic acid level and a modulation of reactive oxygen species (ROS)-related genes, toward a limitation of ROS accumulation, was specifically observed in CMV-infected mycorrhizal plants. Overall, our data indicate that the AM symbiosis influences the development of CMV infection in tomato plants and exerts a priming effect able to enhance tolerance to viral infection.

RevDate: 2020-06-25
CmpDate: 2020-06-25

Guidolin AS, FL Cônsoli (2020)

No fitness costs are induced by Spiroplasma infections of Aphis citricidus reared on two different host plants.

Brazilian journal of biology = Revista brasleira de biologia, 80(2):311-318.

Aphids can harbor several secondary symbionts that alter important aphid-related ecological traits, such as defense against natural enemies, heat tolerance and host plant utilization. One of these secondary symbionts, Spiroplasma, is well known in Drosophila as a sex modulator and by interacting with the host immune system. However, little is known on the effects of Spiroplasma on aphids, such as its influence on the host immune defense against fungi and on host plant utilization. Aphid infections by Spiroplasma are known to be low and few aphid species were reported to be infected with this secondary symbiont, however aphids belonging to the genus Aphis in neotropical regions show high infection rates by Spiroplasma. Thus, we investigated the association of Spiroplasma with the tropical aphid Aphis citricidus through comparative biology experiments on two host plants with different nutritional value to the aphid. We demonstrate Spiroplasma induced no significant fitness costs to A. citricidus on either host plant as no changes in the fitness traits we assessed were observed. Spiroplasma infection only induced sutle changes on host longevity and fecundity. Therefore, we concluded Spiroplasma established a neutral interaction with A. citricidus under the selection pressure we tested, and argue on stress conditions that could better demonstrate the role of Spiroplasma in A. citricidus bioecology and associated costs involved.

RevDate: 2020-06-24

Ronque MUV, Lyra ML, Migliorini GH, et al (2020)

Symbiotic bacterial communities in rainforest fungus-farming ants: evidence for species and colony specificity.

Scientific reports, 10(1):10172 pii:10.1038/s41598-020-66772-6.

Animals may host diverse bacterial communities that can markedly affect their behavioral physiology, ecology, and vulnerability to disease. Fungus-farming ants represent a classical example of mutualism that depends on symbiotic microorganisms. Unraveling the bacterial communities associated with fungus-farming ants is essential to understand the role of these microorganisms in the ant-fungus symbiosis. The bacterial community structure of five species of fungus-farmers (non-leaf-cutters; genera Mycocepurus, Mycetarotes, Mycetophylax, and Sericomyrmex) from three different environments in the Brazilian Atlantic rainforest (lowland forest, restinga forest, and sand dunes) was characterized with amplicon-based Illumina sequencing of 16 S ribosomal RNA gene. Possible differences in bacterial communities between ants internal to the nest (on the fungus garden) and external foragers were also investigated. Our results on the richness and diversity of associated bacteria provide novel evidence that these communities are host- and colony-specific in fungus-farming ants. Indeed, the bacterial communities associated with external foragers differ among the five species, and among colonies of the same species. Furthermore, bacterial communities from internal ants vs. foragers do not differ or differ only slightly within each ant species. This study highlights the importance of describing ant-associated bacterial communities to better understand this host-bacterial interaction in the social environment of insect colonies and provides the foundation for future studies on the ecological and evolutionary processes that drive the success of fungus-farming ants.

RevDate: 2020-06-24

Laffont C, Ivanovici A, Gautrat P, et al (2020)

The NIN transcription factor coordinates CEP and CLE signaling peptides that regulate nodulation antagonistically.

Nature communications, 11(1):3167 pii:10.1038/s41467-020-16968-1.

Legumes tightly regulate nodule number to balance the cost of supporting symbiotic rhizobia with the benefits of nitrogen fixation. C-terminally Encoded Peptides (CEPs) and CLAVATA3-like (CLE) peptides positively and negatively regulate nodulation, respectively, through independent systemic pathways, but how these regulations are coordinated remains unknown. Here, we show that rhizobia, Nod Factors, and cytokinins induce a symbiosis-specific CEP gene, MtCEP7, which positively regulates rhizobial infection. Via grafting and split root studies, we reveal that MtCEP7 increases nodule number systemically through the MtCRA2 receptor. MtCEP7 and MtCLE13 expression in rhizobia-inoculated roots rely on the MtCRE1 cytokinin receptor and on the MtNIN transcription factor. MtNIN binds and transactivates MtCEP7 and MtCLE13, and a NIN Binding Site (NBS) identified within the proximal MtCEP7 promoter is required for its symbiotic activation. Overall, these results demonstrate that a cytokinin-MtCRE1-MtNIN regulatory module coordinates the expression of two antagonistic, symbiosis-related, peptide hormones from different families to fine-tune nodule number.

RevDate: 2020-06-24

Miller JW, Bocke CR, Tresslar AR, et al (2020)

Paraburkholderia Symbionts Display Variable Infection Patterns That Are Not Predictive of Amoeba Host Outcomes.

Genes, 11(6): pii:genes11060674.

Symbiotic interactions exist within a parasitism to mutualism continuum that is influenced, among others, by genes and context. Dynamics of intracellular invasion, replication, and prevalence may underscore both host survivability and symbiont stability. More infectious symbionts might exert higher corresponding costs to hosts, which could ultimately disadvantage both partners. Here, we quantify infection patterns of diverse Paraburkholderia symbiont genotypes in their amoeba host Dictyostelium discoideum and probe the relationship between these patterns and host outcomes. We exposed D. discoideum to thirteen strains of Paraburkholderia each belonging to one of the three symbiont species found to naturally infect D. discoideum: Paraburkholderia agricolaris, Paraburkholderia hayleyella, and Paraburkholderia bonniea. We quantified the infection prevalence and intracellular density of fluorescently labeled symbionts along with the final host population size using flow cytometry and confocal microscopy. We find that infection phenotypes vary across symbiont strains. Symbionts belonging to the same species generally display similar infection patterns but are interestingly distinct when it comes to host outcomes. This results in final infection loads that do not strongly correlate to final host outcomes, suggesting other genetic factors that are not a direct cause or consequence of symbiont abundance impact host fitness.

RevDate: 2020-06-24
CmpDate: 2020-06-24

Yang Q, Huang X, Wang P, et al (2019)

Longitudinal development of the gut microbiota in healthy and diarrheic piglets induced by age-related dietary changes.

MicrobiologyOpen, 8(12):e923.

Diarrhea is one of the most common enteric diseases in young piglets. Diverse factors such as an unstable gut microenvironment, immature intestinal immune system, early supplementary feeding, and weaning often induce dysfunction of gut microbiota, thus leading to a continuing high incidence of diarrhea in piglets. However, few studies have characterized the gut microbiota of diarrheic piglets following changes in diet and during the development of intestinal physiology. In this study, we used 16S rRNA gene sequencing to analyze the dynamic establishment of fecal microbiota in six healthy piglets in response to age-related changes in the diet: sow-reared, early supplementary creep-feeding (sow-reared + starter diet), and weaning (solid nursery diet). We compared the gut microbiota of these six healthy piglets with those of diarrheic piglets during each of the three dietary stages (n = 10 sow-reared, n = 10 early supplementary creep-feeding, and n = 5 weaning). We found that weaning (solid nursery feeding) was the primary factor leading to dynamic colonization by microbiota in healthy piglets, and diarrhea primarily affected the microbial communities of piglets before weaning. Healthy piglets showed a continuous decrease in Lactobacillus and Escherichia, as well as a gradual increase in Prevotella with the transition to solid food. An altered relationship between Prevotella and Escherichia may be the main cause of diarrhea in preweaned piglets, whereas reduced numbers of Bacteroides, Ruminococcus, Bulleidia, and Treponema that are responsible for the digestion and utilization of solid feeds may be related to the onset of postweaning piglet diarrhea. The Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) functional analysis indicated that a reduction in genes involved in carbohydrate metabolism induced by intestinal dysbacteriosis in diarrheic piglets was one of the major causes of diarrhea at the three dietary stages. These findings provide insights into developing an intervention strategy for better management of diarrhea in piglets.

RevDate: 2020-06-24
CmpDate: 2020-06-24

Song Y, Wang M, Zeng R, et al (2019)

Priming and filtering of antiherbivore defences among Nicotiana attenuata plants connected by mycorrhizal networks.

Plant, cell & environment, 42(11):2945-2961.

Arbuscular mycorrhizal fungi (AMF) establish symbiotic associations with a majority of terrestrial plants to form underground common mycorrhizal networks (CMNs) that connect neighbouring plants. Because Nicotiana attenuata plants do not respond to herbivory-elicited volatiles from neighbours, we used this ecological model system to evaluate if CMNs function in interplant transmission of herbivory-elicited responses. A mesocosm system was designed to establish and remove CMNs linking N. attenuata plants to examine the herbivory-elicited metabolic and hormone responses in CMNs-connected "receiver" plants after the elicitation of "donor" plants by wounding (W) treated with Manduca sexta larval oral secretions (OS). AMF colonization increased constitutive jasmonate (JA and JA-Ile) levels in N. attenuata roots but did not affect well-characterized JAs-regulated defensive metabolites in systemic leaves. Interestingly, larger JAs bursts, and higher levels of several amino acids and particular sectors of hydroxygeranyllinalool diterpene glycoside metabolism were elevated in the leaves of W + OS-elicited "receivers" with CMN connections with "donors" that had been W + OS-elicited 6 hr previously. Our results demonstrate that AMF colonization alone does not enhance systemic defence responses but that sectors of systemic responses in leaves can be primed by CMNs, suggesting that CMNs can transmit and even filter defence signalling among connected plants.

RevDate: 2020-06-24
CmpDate: 2020-06-24

Galindo-Castañeda T, Brown KM, Kuldau GA, et al (2019)

Root cortical anatomy is associated with differential pathogenic and symbiotic fungal colonization in maize.

Plant, cell & environment, 42(11):2999-3014.

Root anatomical phenotypes vary among maize (Zea mays) cultivars and may have adaptive value by modifying the metabolic cost of soil exploration. However, the microbial trade-offs of these phenotypes are unknown. We hypothesized that nodal roots of maize with contrasting cortical anatomy have different patterns of mutualistic and pathogenic fungal colonization. Arbuscular mycorrhizal colonization in the field and mesocosms, root rots in the field, and Fusarium verticillioides colonization in mesocosms were evaluated in maize genotypes with contrasting root cortical anatomy. Increased aerenchyma and decreased living cortical area were associated with decreased mycorrhizal colonization in mesocosm and field experiments with inbred genotypes. In contrast, mycorrhizal colonization of hybrids increased with larger aerenchyma lacunae; this increase coincided with larger root diameters of hybrid roots. F. verticillioides colonization was inversely correlated with living cortical area in mesocosm-grown inbreds, and no relation was found between root rots and living cortical area or aerenchyma in field-grown hybrids. Root rots were positively correlated with cortical cell file number and inversely correlated with cortical cell size. Mycorrhizae and root rots were inversely correlated in field-grown hybrids. We conclude that root anatomy is associated with differential effects on pathogens and mycorrhizal colonization of nodal roots in maize.

RevDate: 2020-06-24
CmpDate: 2020-06-24

Chu Q, Sha Z, Maruyama H, et al (2019)

Metabolic reprogramming in nodules, roots, and leaves of symbiotic soybean in response to iron deficiency.

Plant, cell & environment, 42(11):3027-3043.

To elucidate the mechanism of adaptation of leguminous plants to iron (Fe)-deficient environment, comprehensive analyses of soybean (Glycine max) plants (sampled at anthesis) were conducted under Fe-sufficient control and Fe-deficient treatment using metabolomic and physiological approach. Our results show that soybeans grown under Fe-deficient conditions showed lower nitrogen (N) fixation efficiency; however, ureides increased in different tissues, indicating potential N-feedback inhibition. N assimilation was inhibited as observed in the repressed amino acids biosynthesis and reduced proteins in roots and nodules. In Fe-deficient leaves, many amino acids increased, accompanied by the reduction of malate, fumarate, succinate, and α-ketoglutarate, which implies the N reprogramming was stimulated by the anaplerotic pathway. Accordingly, many organic acids increased in roots and nodules; however, enzymes involved in the related metabolic pathway (e.g., Krebs cycle) showed opposite activity between roots and nodules, indicative of different mechanisms. Sugars increased or maintained at constant level in different tissues under Fe deficiency, which probably relates to oxidative stress, cell wall damage, and feedback regulation. Increased ascorbate, nicotinate, raffinose, galactinol, and proline in different tissues possibly helped resist the oxidative stress induced by Fe deficiency. Overall, Fe deficiency induced the coordinated metabolic reprogramming in different tissues of symbiotic soybean plants.

RevDate: 2020-06-23

Kato R, Machida A, Nomoto K, et al (2020)

Maternal approach behaviors toward neonatal calls are impaired by mother's experiences of raising pups with a risk gene variant for autism.

Developmental psychobiology [Epub ahead of print].

How the intrinsic sequence structure of neonatal mouse pup ultrasonic vocalization (USV) and maternal experiences determine maternal behaviors in mice is poorly understood. Our previous work showed that pups with a Tbx1 heterozygous (HT) mutation, a genetic risk for autism spectrum disorder (ASD), emit altered call sequences that do not induce maternal approach behaviors in C57BL6/J mothers. Here, we tested how maternal approach behaviors induced by wild-type and HT USVs are influenced by the mother's experience in raising pups of these two genotypes. The results showed that wild-type USVs were effective in inducing maternal approach behaviors when mothers raised wild-type but not HT pups. The USVs of HT pups were ineffective regardless of whether mothers raised HT or wild-type pups. However, the sequence structure of pup USVs had no effect on the general, non-directional incentive motivation of maternal behaviors. Our data show how the mother's experience with a pup with a genetic risk for ASD alters the intrinsic incentive values of USV sequences in maternal approach behaviors.

RevDate: 2020-06-23

Campo S, Martín-Cardoso H, Olivé M, et al (2020)

Effect of Root Colonization by Arbuscular Mycorrhizal Fungi on Growth, Productivity and Blast Resistance in Rice.

Rice (New York, N.Y.), 13(1):42 pii:10.1186/s12284-020-00402-7.

BACKGROUND: Arbuscular mycorrhizal (AM) fungi form symbiotic associations with roots in most land plants. AM symbiosis provides benefits to host plants by improving nutrition and fitness. AM symbiosis has also been associated with increased resistance to pathogen infection in several plant species. In rice, the effects of AM symbiosis is less studied, probably because rice is mostly cultivated in wetland areas, and plants in such ecosystems have traditionally been considered as non-mycorrhizal. In this study, we investigated the effect of AM inoculation on performance of elite rice cultivars (Oryza sativa, japonica subspecies) under greenhouse and field conditions, focusing on growth, resistance to the rice blast fungus Magnaporthe oryzae and productivity.

RESULTS: The response to inoculation with either Funneliformis mosseae or Rhizophagus irregularis was evaluated in a panel of 12 rice cultivars. Root colonization was confirmed in all rice varieties. Under controlled greenhouse conditions, R. irregularis showed higher levels of root colonization than F. mosseae. Compared to non-inoculated plants, the AM-inoculated plants had higher Pi content in leaves. Varietal differences were observed in the growth response of rice cultivars to inoculation with an AM fungus, which were also dependent on the identity of the fungus. Thus, positive, negligible, and negative responses to AM inoculation were observed among rice varieties. Inoculation with F. mosseae or R. irregularis also conferred protection to the rice blast fungus, but the level of mycorrhiza-induced blast resistance varied among host genotypes. Rice seedlings (Loto and Gines varieties) were pre-inoculated with R. irregularis, transplanted into flooded fields, and grown until maturity. A significant increase in grain yield was observed in mycorrhizal plants compared with non-mycorrhizal plants, which was related to an increase in the number of panicles.

CONCLUSION: Results here presented support that rice plants benefit from the AM symbiosis while illustrating the potential of using AM fungi to improve productivity and blast resistance in cultivated rice. Differences observed in the mycorrhizal responsiveness among the different rice cultivars in terms of growth promotion and blast resistance indicate that evaluation of benefits received by the AM symbiosis needs to be carefully evaluated on a case-by-case basis for efficient exploitation of AM fungi in rice cultivation.

RevDate: 2020-06-23

Ren FR, Sun X, Wang TY, et al (2020)

Biotin provisioning by horizontally transferred genes from bacteria confers animal fitness benefits.

The ISME journal pii:10.1038/s41396-020-0704-5 [Epub ahead of print].

Insect symbionts are widespread in nature and lateral gene transfer is prevalent in insect symbiosis. However, the function of horizontally transferred genes (HTGs) in insect symbiosis remains speculative, including the mechanism that enables insects to feed on plant phloem deficient in B vitamins. Previously, we found there is redundancy in biotin synthesis pathways from both whitefly Bemisia tabaci and symbiotic Hamiltonella due to the presence of whitefly HTGs. Here, we demonstrate that elimination of Hamiltonella decreased biotin levels but elevated the expression of horizontally transferred biotin genes in whiteflies. HTGs proteins exhibit specific expression patterns in specialized insect cells called bacteriocytes housing symbionts. Complementation with whitefly HTGs rescued E. coli biotin gene knockout mutants. Furthermore, silencing whitefly HTGs in Hamiltonella-infected whiteflies reduced biotin levels and hindered adult survival and fecundity, which was partially rescued by biotin supplementation. Each of horizontally transferred biotin genes are conserved in various laboratory cultures and species of whiteflies with geographically diverse distributions, which shares an evolutionary origin. We provide the first experimental evidence that biotin synthesized through acquired HTGs is important in whiteflies and may be as well in other animals. Our findings suggest that B vitamin provisioning in animal-microbe symbiosis frequently evolved from bacterial symbionts to animal hosts through horizontal gene transfer events. This study will also shed light on how the animal genomes evolve through functional transfer of genes with bacterial origin in the wider contexts of microbial ecology.

RevDate: 2020-06-23

Debortoli G, Abbatangelo C, Ceballos F, et al (2020)

Novel insights on demographic history of tribal and caste groups from West Maharashtra (India) using genome-wide data.

Scientific reports, 10(1):10075 pii:10.1038/s41598-020-66953-3.

The South Asian subcontinent is characterized by a complex history of human migrations and population interactions. In this study, we used genome-wide data to provide novel insights on the demographic history and population relationships of six Indo-European populations from the Indian State of West Maharashtra. The samples correspond to two castes (Deshastha Brahmins and Kunbi Marathas) and four tribal groups (Kokana, Warli, Bhil and Pawara). We show that tribal groups have had much smaller effective population sizes than castes, and that genetic drift has had a higher impact in tribal populations. We also show clear affinities between the Bhil and Pawara tribes, and to a lesser extent, between the Warli and Kokana tribes. Our comparisons with available modern and ancient DNA datasets from South Asia indicate that the Brahmin caste has higher Ancient Iranian and Steppe pastoralist contributions than the Kunbi Marathas caste. Additionally, in contrast to the two castes, tribal groups have very high Ancient Ancestral South Indian (AASI) contributions. Indo-European tribal groups tend to have higher Steppe contributions than Dravidian tribal groups, providing further support for the hypothesis that Steppe pastoralists were the source of Indo-European languages in South Asia, as well as Europe.

RevDate: 2020-06-23

Arapov TD, Kim J, Cronin RM, et al (2020)

Programmed degradation of chemotaxis proteins in Sinorhizobium meliloti: Features in the C-terminal region control McpU degradation.

Journal of bacteriology pii:JB.00124-20 [Epub ahead of print].

Chemotaxis and motility are important traits supporting bacterial survival in various ecological niches and in pathogenic and symbiotic host interaction. Chemotactic stimuli are sensed by chemoreceptors or Methyl-accepting Chemotaxis Proteins (MCPs), which direct the swimming behavior of the bacterial cell. In this study, we present evidence that the cellular abundance of chemoreceptors in the plant-symbiont Sinorhizobium meliloti can be altered by the addition of several to as few as one amino acid residue, and including common epitope tags such as 3xFLAG and 6xHis to their C-termini. To further dissect this phenomenon and its underlying molecular mechanism, we focused on a detailed analysis of the amino acid sensor McpU. Controlled proteolysis is important for the maintenance of an appropriate stoichiometry of chemoreceptors and between chemoreceptors and chemotactic signaling proteins, which is essential for an optimal chemotactic response. We hypothesized that enhanced stability is due to interference with protease binding, thus affecting proteolytic efficacy. Location of the protease recognition site was defined through McpU stability measurements in a series of deletion and amino acid substitution mutants. Deletions in the putative protease recognition site had similar effects on McpU abundance as did extensions at the C-terminus. Our results provide evidence that the programmed proteolysis of chemotaxis proteins in S. meliloti is cell-cycle regulated. This post-translational control together with regulatory pathways on the transcriptional level limit the chemotaxis machinery to early exponential growth. Our study identified parallels to cell-cycle dependent processes during asymmetric cell division in Caulobacter crescentus.IMPORTANCE The symbiotic bacterium Sinorhizobium meliloti contributes greatly to growth of the agriculturally valuable host plant alfalfa by fixing atmospheric nitrogen. Chemotaxis of S. meliloti cells towards alfalfa roots mediates this symbiosis. The present study establishes programmed proteolysis as a factor in the maintenance of the S. meliloti chemotaxis system. Knowledge about cell-cycle dependent, targeted, and selective proteolysis in S. meliloti is important to understand the molecular mechanisms of maintaining a suitable chemotaxis response. While the role of regulated protein turnover in the cell-cycle progression of Caulobacter crescentus is well understood, these pathways are just beginning to be characterized in S. meliloti In addition, our study should alert about the cautionary use of epitope tags for protein quantification.

RevDate: 2020-06-23

Sood M, Kapoor D, Kumar V, et al (2020)

Trichoderma: The "Secrets" of a Multitalented Biocontrol Agent.

Plants (Basel, Switzerland), 9(6): pii:plants9060762.

The plant-Trichoderma-pathogen triangle is a complicated web of numerous processes. Trichoderma spp. are avirulent opportunistic plant symbionts. In addition to being successful plant symbiotic organisms, Trichoderma spp. also behave as a low cost, effective and ecofriendly biocontrol agent. They can set themselves up in various patho-systems, have minimal impact on the soil equilibrium and do not impair useful organisms that contribute to the control of pathogens. This symbiotic association in plants leads to the acquisition of plant resistance to pathogens, improves developmental processes and yields and promotes absorption of nutrient and fertilizer use efficiency. Among other biocontrol mechanisms, antibiosis, competition and mycoparasitism are among the main features through which microorganisms, including Thrichoderma, react to the presence of other competitive pathogenic organisms, thereby preventing or obstructing their development. Stimulation of every process involves the biosynthesis of targeted metabolites like plant growth regulators, enzymes, siderophores, antibiotics, etc. This review summarizes the biological control activity exerted by Trichoderma spp. and sheds light on the recent progress in pinpointing the ecological significance of Trichoderma at the biochemical and molecular level in the rhizosphere as well as the benefits of symbiosis to the plant host in terms of physiological and biochemical mechanisms. From an applicative point of view, the evidence provided herein strongly supports the possibility to use Trichoderma as a safe, ecofriendly and effective biocontrol agent for different crop species.

RevDate: 2020-06-22

Zanetti ME, Blanco F, Reynoso M, et al (2020)

To keep or not to keep: mRNA stability and translatability in root nodule symbiosis.

Current opinion in plant biology, 56:109-117 pii:S1369-5266(20)30052-2 [Epub ahead of print].

Post-transcriptional control of gene expression allows plants to rapidly adapt to changes in their environment. Under low nitrogen conditions, legume plants engage into a symbiosis with soil bacteria that results in the formation of root nodules, where bacteria are allocated and fix atmospheric nitrogen for the plant's benefit. Recent studies highlighted the importance of small RNA-mediated mechanisms in the control of bacterial infection, nodule organogenesis, and the long-distance signaling that balances plant growth and nodulation. Examples of such mechanisms are shoot-to-root mobile microRNAs and small RNA fragments derived from degradation of bacterial transfer RNAs that repress complementary mRNAs in the host plant. Mechanisms of selective mRNA translation also contribute to rapidly modulate the expression of nodulation genes in a cell-specific manner during symbiosis. Here, the most recent advances made on the regulation of mRNA stability and translatability, and the emerging roles of long non-coding RNAs in symbiosis are summarized.

RevDate: 2020-06-22

Naik VR, Munikumar M, Ramakrishna U, et al (2020)

Remdesivir (GS-5734) as a therapeutic option of 2019-nCOV main protease - in silico approach.

Journal of biomolecular structure & dynamics [Epub ahead of print].

2019 - Novel Coronavirus (2019-nCOV), enclosed large genome positive-sense RNA virus characterized by crown-like spikes that protrude from their surface, and have a distinctive replication strategy. The 2019-nCOV belongs to the Coronaviridae family, principally consists of virulent pathogens showing zoonotic property, has emerged as a pandemic outbreak with high mortality and high morbidity rate around the globe and no therapeutic vaccine or drugs against 2019-nCoV are discovered till now. In this study, in silico methods and algorithms were used for sequence, structure analysis and molecular docking on Mpro of 2019-nCOV. The co-crystal structure of 2019-nCOV protease, 6LU7 have ∼99% identity with SARS-CoV protease. The 6LU7 residues, Cys145 and His164 are playing a significant role in replication and are essential for the survival of 2019-nCOV. Alongside, 2019-nCOV Mpro sequence is non-homologous to human host-pathogen. Complete genome sequence analysis, structural and molecular docking results revealed that Remdesivir is having a better binding affinity with -8.2 kcal/mol than the rest of protease inhibitors, and peptide. Remdesivir is strongly forming h-bonds with crucial Mpro residues, Cys145, and His164. Further, MD simulation analysis also confirmed, that these residues are forming H-bond with Remdesivir during 100 ns simulations run and found stable (∼99%) by RMSD and RMSF. Thus, present in silico study at molecular approaches suggest that, Remdesivir is a potent therapeutic inhibitor against 2019-nCoV.Communicated by Ramaswamy H. Sarma.

RevDate: 2020-06-22

Delamuta JRM, Scherer AJ, Ribeiro RA, et al (2020)

Genetic diversity of Agrobacterium species isolated from nodules of common bean and soybean in Brazil, Mexico, Ecuador and Mozambique, and description of the new species Agrobacterium fabacearum sp. nov.

International journal of systematic and evolutionary microbiology [Epub ahead of print].

Agrobacterium strains are associated with soil, plants and animals, and known mainly by their pathogenicity. We studied 14 strains isolated from nodules of healthy soybean and common bean plants in Brazil, Mexico, Ecuador and Mozambique. Sequence analysis of the 16S rRNA gene positioned the strains as Agrobacterium, but with low phylogenetic resolution. Multilocus sequence analysis (MLSA) of three partial housekeeping genes (glnII, gyrB and recA) positioned the strains in four distinct clades, with Agrobacterium pusense, Agrobacterium deltaense, Agrobacterium radiobacter and Agrobacterium sp. genomospecies G1. Analysis by BOX-PCR revealed high intraspecies diversity. Genomic analysis of representative strains of the three clades indicated that they carry the protelomerase telA gene, and MLSA analysis with six complete housekeeping genes (atpD, glnII, gyrB, recA, rpoB and thrC), as well as average nucleotide identity (less than 90 % with closest species) and digital DNA-DNA hybridization (less than 41 % with closest species) revealed that strain CNPSo 675T and Agrobacterium sp. genomospecies G1 compose a new species. Other phenotypic and genotypic characteristics were determined for the new clade. Although not able to re-nodulate the host, we hypothesize that several strains of Agrobacterium are endophytes in legume nodules, where they might contribute to plant growth. Our data support the description of the CNPSo 675T and Agrobacterium sp. genomospecies G1 strains as a new species, for which the name Agrobacterium fabacearum is proposed. The type strain is CNPSo 675T (=UMR 1457T=LMG 31642T) and is also deposited in other culture collections.

RevDate: 2020-06-22
CmpDate: 2020-06-22

Clanner-Engelshofen BM, French LE, M Reinholz (2020)

Methods for extraction and ex-vivo experimentation with the most complex human commensal, Demodex spp.

Experimental & applied acarology, 80(1):59-70.

Demodex spp. mites are the most complex organisms of the human skin microbiome and were discovered more than 175 years ago, yet only little basic research is published about them. As they can be pathophysiologically relevant ectoparasites associated with rosacea, pityriasis folliculorum, and other inflammatory skin diseases, more research should be encouraged. Being a large microorganism or a tiny animal, there are no established basic methods to handle these mites. Here, we describe techniques enabling the extraction of Demodex mites from human skin, their analysis in different ex-vivo settings, the lysis of their exoskeleton, their preservation by freezing, and observation microscopically using specific fluorescent dyes or their inherent autofluorescence. These procedures should facilitate future Demodex research and fuel further the generation of knowledge. Furthermore it is intended to ultimatively enable the mite's cultivation in vitro and reveal its pathophysiological mechanisms.

RevDate: 2020-06-22
CmpDate: 2020-06-22

Reinhardt C (2019)

The Microbiota: A Microbial Ecosystem Built on Mutualism Prevails.

Journal of innate immunity, 11(5):391-392.

RevDate: 2020-06-22
CmpDate: 2020-06-22

McCutcheon JP, Boyd BM, C Dale (2019)

The Life of an Insect Endosymbiont from the Cradle to the Grave.

Current biology : CB, 29(11):R485-R495.

Host-beneficial endosymbioses, which are formed when a microorganism takes up residence inside another cell and provides a fitness advantage to the host, have had a dramatic influence on the evolution of life. These intimate relationships have yielded the mitochondrion and the plastid (chloroplast) - the ancient organelles that in part define eukaryotic life - along with many more recent associations involving a wide variety of hosts and microbial partners. These relationships are often envisioned as stable associations that appear cooperative and persist for extremely long periods of time. But recent evidence suggests that this stable state is often born from turbulent and conflicting origins, and that the apparent stability of many beneficial endosymbiotic relationships - although certainly real in many cases - is not an inevitable outcome of these associations. Here we review how stable endosymbioses form, how they are maintained, and how they sometimes break down and are reborn. We focus on relationships formed by insects and their resident microorganisms because these symbioses have been the focus of significant empirical work over the last two decades. We review these relationships over five life stages: origin, birth, middle age, old age, and death.

RevDate: 2020-06-22
CmpDate: 2020-06-22

Bascompte J (2019)

Mutualism and biodiversity.

Current biology : CB, 29(11):R467-R470.

Mutualism is a type of interaction in which both partners benefit from each other. For example, a butterfly receives nectar, a rich source of food, from the flower of a plant and in turn moves pollen from that plant to another far away (Figure 1). In order to reflect about the widespread nature of mutualism, John N. Thompson proposed the following thought experiment: try to imagine a plant species that is viable in its natural habitat without using on top of its own nuclear genome the genomes of a mitochondrion, a chloroplast, of several mycorrhizal fungi, of several insects to pollinate it and of several species of bird to disperse its seeds. Mutualism is everywhere and it is assumed that mutualistic interactions have played a major role in the diversification of life on Earth. An often-cited example is the rich adaptive radiation of the flowering plants (angiosperms), with about 300,000 described species. Flowering plants originated around 160 million years ago and diversified fast during the Early Cretaceous, so that by around 120 million years ago they had become widespread. It is generally assumed that such a fast diversification is largely the result of the mutualistic interaction with pollinators. Thus, mutualism has been most likely shaping the diversity of species on Earth from an early stage. But the relationships between mutualism and diversity are not yet clear, mainly because mutualism has traditionally been studied within pairs or small groups of species. Also, mutualism has historically been studied in isolation from competition, so it is unclear how these two forces balance each other in ecological communities.

RevDate: 2020-06-22
CmpDate: 2020-06-22

Leung CY, JS Weitz (2019)

Not by (Good) Microbes Alone: Towards Immunocommensal Therapies.

Trends in microbiology, 27(4):294-302.

Commensal bacteria have been identified as critical drivers of host resilience to pathogen invasion. The resulting 'competitive exclusion' of pathogens by commensals can arise via multiple mechanisms, including direct competition for sites of colonization, production of metabolic products that inhibit pathogen growth, and modulation of host immune responses (including differential targeting of pathogens). Nonetheless, suppression of pathogens through the combined action of commensals and host immunity is far from inevitable. Here, we utilize a simple, within-host ecosystem model to explore the microbiological and immunological conditions that govern the fate of pathogen colonization. Model analysis leads to the hypothesis that robust elimination of pathogens requires a synergy between host immune defense and commensal bacteria. That is, pathogens can proliferate and establish persistent infections if either the state of the microbiota or the host immune defense falls below critical levels. Leveraging these findings, we advocate for improved integration of nonlinear dynamic models in efforts to understand infection dynamics in an immunological context. Doing so may provide new opportunities to establish baseline indicators for healthy microbiomes and to develop improved therapeutics through targeted modification of feedback amongst commensals and between commensals and the immune system.

RevDate: 2020-06-22
CmpDate: 2020-06-22

Esser D, Lange J, Marinos G, et al (2019)

Functions of the Microbiota for the Physiology of Animal Metaorganisms.

Journal of innate immunity, 11(5):393-404.

Animals are usually regarded as independent entities within their respective environments. However, within an organism, eukaryotes and prokaryotes interact dynamically to form the so-called metaorganism or holobiont, where each partner fulfils its versatile and crucial role. This review focuses on the interplay between microorganisms and multicellular eukaryotes in the context of host physiology, in particular aging and mucus-associated crosstalk. In addition to the interactions between bacteria and the host, we highlight the importance of viruses and nonmodel organisms. Moreover, we discuss current culturing and computational methodologies that allow a deeper understanding of underlying mechanisms controlling the physiology of metaorganisms.

RevDate: 2020-06-20

Maggioni D, Schiavo A, Ostrovsky AN, et al (2020)

Cryptic species and host specificity in the bryozoan-associated hydrozoan Zanclea divergens (Hydrozoa, Zancleidae).

Molecular phylogenetics and evolution pii:S1055-7903(20)30165-2 [Epub ahead of print].

Zanclea divergens is a tropical hydrozoan living in symbiotic association with bryozoans and currently reported from Papua New Guinea, Indonesia, and Maldives. Here, we used an integrative approach to assess the morpho-molecular diversity of the species across the Indo-Pacific. Phylogenetic and species delimitation analyses based on seven mitochondrial and nuclear loci revealed four well-supported molecular lineages corresponding to cryptic species, and representing a Pacific clade, an Indian clade, and two Red Sea clades. Since the general polyp morphology was almost identical in all samples, the nematocyst capsules were measured and analysed to search for possible fine-scale differences, and their statistical treatment revealed a significant difference in terms of length and width among the clades investigated. All Zanclea divergens specimens were specifically associated with cheilostome bryozoans belonging to the genus Celleporaria. The Pacific and Indian clades were associated with Celleporaria sp. and C. vermiformis, respectively, whereas both Red Sea lineages were associated with C. pigmentaria. Nevertheless, the sequencing of host bryozoans revealed that one of the Red Sea hydrozoan clades is associated with two morphologically undistinguishable, but genetically divergent, bryozoan species. Overall, our results show that Z. divergens is a species complex composed of morphologically cryptic lineages showing partially disjunct distributions and host specificity. The presence of two sympatric lineages living on the same host species reveal complex dynamics of diversification, and future research aimed at understanding their diversification process will likely improve our knowledge on the mechanisms of speciation among currently sympatric cryptic species.

RevDate: 2020-06-20

Plett JM, Plett KL, Wong-Bajracharya J, et al (2020)

Mycorrhizal effector PaMiSSP10b alters polyamine biosynthesis in Eucalyptus root cells and promotes root colonization.

The New phytologist [Epub ahead of print].

Pathogenic microbes are known to manipulate the defences of their hosts through the production of secreted effector proteins. More recently, mutualistic mycorrhizal fungi have also been described as using these secreted effectors to promote host colonization. Here we characterise a mycorrhiza-induced small secreted effector protein of 10 kDa produced by the ectomycorrhizal fungus Pisolithus albus, PaMiSSP10b. We demonstrate that PaMiSSP10b is secreted from fungal hyphae, enters the cells of its host, Eucalyptus grandis, and interacts with an S-adenosyl methionine decarboxylase (AdoMetDC) in the polyamine pathway. Plant polyamines are regulatory molecules integral to the plant immune system during microbial challenge. Using biochemical and transgenic approaches we show that expression of PaMiSSP10b influences levels of polyamines in the plant roots as it enhances the enzymatic activity of AdoMetDC and increases the biosynthesis of higher polyamines. This ultimately favours the colonization success of P. albus. These results identify a new mechanism by which mutualistic microbes are able to manipulate the host´s enzymatic pathways to favour colonization.

RevDate: 2020-06-20

Chathoth K, Martin B, Cornelis P, et al (2020)

The events that may contribute to subgingival dysbiosis: a focus on the interplay between iron, sulfide and oxygen.

FEMS microbiology letters pii:5860280 [Epub ahead of print].

This minireview considers the disruption of the host-microbiota harmless symbiosis in the subgingival niche. The establishment of a chronic infection by subversion of a commensal microbiota results from a complex and multiparametric sequence of events. This review narrows down to the interplay between oxygen, iron and sulfide that can result in a vicious cycle that would favour peroxigenic and glutathione producing streptococci as well as sulfidogenic anaerobic pathogens in the subgingival niche. We propose hypothesis and discuss strategies for the therapeutic modulation of the microbiota to prevent periodontitis and promote oral health.

RevDate: 2020-06-20

Band-Schmidt CJ, Zumaya-Higuera MG, López-Cortés DJ, et al (2020)

Allelopathic effects of Margalefidinium polykrikoides and Gymnodinium impudicum in the growth of Gymnodinium catenatum.

Harmful algae, 96:101846.

Harmful algae blooms (HABs) are characterized for the coexistence of phytoplankton species with dynamic and complex biotic interactions (e.g., competition, symbiosis, predation, parasitism, allelopathy), that occur at fine temporal and spatial scales, and are relevant to understand the role that different species of phytoplankton play in the regulation of HABs. In this work the allelopathic effects of Margalefidinium polykrikoides (=Cochlodinium polykrikoides) and Gymnodinium impudicum on Gymnodinium catenatum were evaluated. The allelopathic abilities of M. polykrikoides and G. impudicum were investigated in bi-algal culture experiments and in trials in which target species were co-cultured, separated by a 10 μm membrane to prevent a direct cell-to-cell contact; and also by the addition of different volumes of culture media without cells. For all trials, cells of each species were harvested during exponential phase and cultured together by triplicate at three relative abundances: 1:1 (200 Cells mL-1 of each species, G. catenatum and M. polykrikoides or G. impudicum), 2:1 (400 Cells mL-1 of G. catenatum and 200 Cells mL-1 of M. polykrikoides or G. impudicum), and 1:2 (200 cells mL-1 of G. catenatum and 400 Cells mL-1 of M. polykrikoides or G. impudicum). All bioassays were carried out by triplicate in 250 mL Erlenmeyer flasks with 150 mL of modified GSe medium with an initial inoculum of 200 or 400 Cells mL-1. During experiments G. catenatum abundances were enumerated daily. In bi-algal culture experiments mortalities of G. catenatum were from 50% to 100% after 48 h of cell contact with M. polykrikoides or G. impudicum. In the case of culture media without cells, only M. polykrikoides caused a decrease in the cell abundance and growth rate of G. catenatum. Morphological changes occurred in G. catenatum when in contact with M. polykrikoides and G. impudicum, such as membrane shedding, prominent nucleus, loss of flagella, cell lysis, as well as the separation of long chains into individual cells. These results suggest that in the natural environment M. polykrikoides and G. impudicum have allelopathic interactions in G. catenatum, which could negatively affect its growth and survival, indicating that these species could displace blooms of G. catenatum.

RevDate: 2020-06-19

Prudence SMM, Addington E, Castaño-Espriu L, et al (2020)

Advances in actinomycete research: an ActinoBase review of 2019.

Microbiology (Reading, England) [Epub ahead of print].

The actinomycetes are Gram-positive bacteria belonging to the order Actinomycetales within the phylum Actinobacteria. They include members with significant economic and medical importance, for example filamentous actinomycetes such as Streptomyces species, which have a propensity to produce a plethora of bioactive secondary metabolites and form symbioses with higher organisms, such as plants and insects. Studying these bacteria is challenging, but also fascinating and very rewarding. As a Microbiology Society initiative, members of the actinomycete research community have been developing a Wikipedia-style resource, called ActinoBase, the purpose of which is to aid in the study of these filamentous bacteria. This review will highlight 10 publications from 2019 that have been of special interest to the ActinoBase community, covering 4 major components of actinomycete research: (i) development and regulation; (ii) specialized metabolites; (iii) ecology and host interactions; and (iv) technology and methodology.

RevDate: 2020-06-19

Fabiańska I, Pesch L, Koebke E, et al (2020)

Neighboring plants divergently modulate effects of loss-of-function in maize mycorrhizal phosphate uptake on host physiology and root fungal microbiota.

PloS one, 15(6):e0232633 pii:PONE-D-20-03394.

Maize, a main crop worldwide, establishes a mutualistic symbiosis with arbuscular mycorrhizal (AM) fungi providing nutrients to the roots from soil volumes which are normally not in reach of the non-colonized root. The mycorrhizal phosphate uptake pathway (MPU) spans from extraradical hyphae to root cortex cells housing fungal arbuscules and promotes the supply of phosphate to the mycorrhizal host in exchange for photosynthetic carbon. This symbiotic association with the mycobiont has been shown to affect plant host nutritional status and growth performance. However, whether and how the MPU affects the root microbial community associated with mycorrhizal hosts in association with neighboring plants, remains to be demonstrated. Here the maize germinal Mu transposon insertion mutant pht1;6, defective in mycorrhiza-specific Pi transporter PHT1;6 gene, and wild type B73 (wt) plants were grown in mono- and mixed culture and examined under greenhouse and field conditions. Disruption of the MPU in pht1;6 resulted in strongly diminished growth performance, in reduced P allocation to photosynthetic source leaves, and in imbalances in leaf elemental composition beyond P. At the microbial community level a loss of MPU activity had a minor effect on the root-associated fungal microbiome which was almost fully restricted to AM fungi of the Glomeromycotina. Moreover, while wt grew better in presence of pht1;6, pht1;6 accumulated little biomass irrespective of whether it was grown in mono- or mixed culture and despite of an enhanced fungal colonization of its roots in co-culture with wt. This suggested that a functional MPU is prerequisite to maintain maize growth and that neighboring plants competed for AM fungal Pi in low P soil. Thus future strategies towards improving yield in maize populations on soils with low inputs of P fertilizer could be realized by enhancing MPU at the individual plant level while leaving the root-associated fungal community largely unaffected.

RevDate: 2020-06-19

Dorival J, Philys S, Giuntini E, et al (2020)

Structural and enzymatic characterisation of the Type III effector NopAA (=GunA) from Sinorhizobium fredii USDA257 reveals a Xyloglucan hydrolase activity.

Scientific reports, 10(1):9932 pii:10.1038/s41598-020-67069-4.

Rhizobia are nitrogen-fixing soil bacteria that can infect legume plants to establish root nodules symbiosis. To do that, a complex exchange of molecular signals occurs between plants and bacteria. Among them, rhizobial Nops (Nodulation outer proteins), secreted by a type III secretion system (T3SS) determine the host-specificity for efficient symbiosis with plant roots. Little is known about the molecular function of secreted Nops (also called effectors (T3E)) and their role in the symbiosis process. We performed the structure-function characterization of NopAA, a T3E from Sinorhizobium fredii by using a combination of X-ray crystallography, biochemical and biophysical approaches. This work displays for the first time a complete structural and biochemical characterization of a symbiotic T3E. Our results showed that NopAA has a catalytic domain with xyloglucanase activity extended by a N-terminal unfolded secretion domain that allows its secretion. We proposed that these original structural properties combined with the specificity of NopAA toward xyloglucan, a key component of root cell wall which is also secreted by roots in the soil, can give NopAA a strategic position to participate in recognition between bacteria and plant roots and to intervene in nodulation process.

RevDate: 2020-06-19

Sarapat S, Songwattana P, Longtonglang A, et al (2020)

Effects of Increased 1-Aminocyclopropane-1-Carboxylate (ACC) Deaminase Activity in Bradyrhizobium sp. SUTN9-2 on Mung Bean Symbiosis under Water Deficit Conditions.

Microbes and environments, 35(3):.

Bacteria exhibiting 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, which inhibits the biosynthesis of ethylene in higher plants, promote plant growth through the degradation of ethylene precursors, such as ACC. ACC deaminase activity in Bradyrhizobium sp. SUTN9-2 was enhanced by genetic engineering and adaptive laboratory evolution (ALE)-based methods. The transferal of a plasmid containing the acdR and acdS genes into SUTN9-2 was genetic engineering improved, while the ALE method was performed based on the accumulation of an adaptive bacterial population that continuously grew under specified growth conditions for a long time. ACC deaminase enzyme activity was 8.9-fold higher in SUTN9-2:pMG103::acdRS and 1.4-fold higher in SUTN9-2 (ACCDadap) than in the wild-type strain. The effects of increased activity were examined in the host plant (Vigna radiata (L.) R.Wilczek SUT1). The improved strains enhanced nodulation in early stage of plant growth. SUTN9-2:pMG103::acdRS also maintained nitrogen fixation under water deficit conditions and increased the plant biomass after rehydration. Changes in nucleotides and amino acids in the AcdS protein of SUTN9-2 (ACCDadap) were then investigated. Some nucleotides predicted to be located in the ACC-binding site were mutated. These mutations may have increased ACC deaminase activity, which enhanced both symbiotic interactions and drought tolerance and promoted recovery after rehydration more than lower ACC deaminase activity. Adaptive evolution represents a promising strategy for further applications in the field.

RevDate: 2020-06-19

Mayers CG, Harrington TC, Mcnew DL, et al (2020)

Four mycangium types and four genera of ambrosia fungi suggest a complex history of fungus farming in the ambrosia beetle tribe Xyloterini.

Mycologia [Epub ahead of print].

Ambrosia beetles farm fungal cultivars (ambrosia fungi) and carry propagules of the fungal mutualists in storage organs called mycangia, which occur in various body parts and vary greatly in size and complexity. The evolution of ambrosia fungi is closely tied to the evolution and development of the mycangia that carry them. The understudied ambrosia beetle tribe Xyloterini included lineages with uncharacterized ambrosia fungi and mycangia, which presented an opportunity to test whether developments of different mycangium types in a single ambrosia beetle lineage correspond with concomitant diversity in their fungal mutualists. We collected representatives of all three Xyloterini genera (Trypodendron, Indocryphalus, and Xyloterinus politus) and characterized their ambrosia fungi in pure culture and by DNA sequencing. The prothoracic mycangia of seven Trypodendron species all yielded Phialophoropsis (Microascales) ambrosia fungi, including three new species, although these relationships were not all species specific. Indocryphalus mycangia are characterized for the first time in the Asian I. pubipennis. They comprise triangular prothoracic cavities substantially smaller than those of Trypodendron and unexpectedly carry an undescribed species of Toshionella (Microascales), which are otherwise ambrosia fungi of Asian Scolytoplatypus (Scolytoplatypodini). Xyloterinus politus has two different mycangia, each with a different ambrosia fungus: Raffaelea cf. canadensis RNC5 (Ophiostomatales) in oral mycangia of both sexes and Kaarikia abrahamsonii (Sordariomycetes, genus incertae sedis with affinity for Distoseptisporaceae), a new genus and species unrelated to other known ambrosia fungi, in shallow prothoracic mycangia of females. In addition to their highly adapted mycangial mutualists, Trypodendron and X. politus harbor a surprising diversity of facultative symbionts in their galleries, including Raffaelea. A diversity of ambrosia fungi and mycangia suggest multiple ancestral cultivar captures or switches in the history of tribe Xyloterini, each associated with unique adaptations in mycangium anatomy. This further supports the theory that developments of novel mycangium types are critical events in the evolution of ambrosia beetles and their coadapted fungal mutualists.

RevDate: 2020-06-19

Wang J, Hou W, Christensen MJ, et al (2020)

Role of Epichloë Endophytes in Improving Host Grass Resistance Ability and Soil Properties.

Journal of agricultural and food chemistry [Epub ahead of print].

The past decade has witnessed significant advances in understanding the interaction between grasses and systemic fungal endophytes of the genus Epichloë, with evidence that plants have evolved multiple strategies to cope with abiotic stresses by reprogramming physiological responses. Soil nutrients directly affect plant growth, while soil microbes are also closely connected to plant growth and health. Epichloë endophytes could affect soil fertility by modifying soil nutrient contents and soil microbial diversity. Therefore, we analyze recent advances in our understanding of the role of Epichloë endophytes under the various abiotic stresses and the role of grass-Epichloë symbiosis on soil fertility. Various cool-season grasses are infected by Epichloë species, which contribute to health, growth, persistence, and seed survival of host grasses by regulating key systems, including photosynthesis, osmotic regulation, and antioxidants and activity of key enzymes of host physiology processes under abiotic stresses. The Epichloë endophyte offers significant prospects to magnify the crop yield, plant resistance, and food safety in ecological systems by modulating soil physiochemical properties and soil microbes. The enhancing resistance of host grasses to abiotic stresses by an Epichloë endophyte is a complex manifestation of different physiological and biochemical events through regulating soil properties and soil microbes by the fungal endophyte. The Epichloë-mediated mechanisms underlying regulation of abiotic stress responses are involved in osmotic adjustment, antioxidant machinery, photosynthetic system, and activity of key enzymes critical in developing plant adaptation strategies to abiotic stress. Therefore, the Epichloë endophytes are an attractive choice in increasing resistance of plants to abiotic stresses and are also a good candidate for improving soil fertility and regulating microbial diversity to improve plant growth.

RevDate: 2020-06-19

Álvarez C, Navarro JA, Molina-Heredia FP, et al (2020)

Endophytic Colonization of Rice (Oryza sativa L.) by the Symbiotic Strain Nostoc punctiforme PCC 73102.

Molecular plant-microbe interactions : MPMI [Epub ahead of print].

Cyanobacteria are phototrophic microorganisms able to establish nitrogen-fixing symbiotic associations with representatives of all four of the major phylogenetic divisions of terrestrial plants. Despite increasing knowledge on the beneficial effects of cyanobacteria in rice fields, the information about the interaction between these microorganisms and rice at the molecular and structural levels is still limited. We have used the model nitrogen-fixing cyanobacterium Nostoc punctiforme to promote a long-term stable endophytic association with rice. Inoculation with this strain of hydroponic cultures of rice produces a fast adherence of the cyanobacterium to rice roots. At longer times, cyanobacterial growth in the proximity of the roots increased until reaching a plateau. This latter phase coincides with the intracellular colonization of the root epidermis and exodermis. Structural analysis of the roots revealed that the cyanobacterium use an apoplastic route to colonize the plant cells. Moreover, plant roots inoculated with N. punctiforme show both the presence of heterocysts and nitrogenase activity, resulting in the promotion of plant growth under nitrogen deficiency, thus providing benefits for the plant.

RevDate: 2020-06-19
CmpDate: 2020-06-19

Takeuchi I, Takaichi D, Katsumata M, et al (2020)

Succession of delayed fluorescence correlated with coral bleaching in the hermatypic coral Acropora tenuis.

Marine pollution bulletin, 154:111008.

We investigated coral bleaching by monitoring colour changes and measuring the delayed fluorescence (DF) of symbiotic dinoflagellates in the hermatypic coral Acropora tenuis, exposed to 1.0 μg/L Irgarol 1051 (photosystem II herbicide) for 14 d. The Irgarol concentration corresponded to those from international port regions of the world. The coral colour and DFs under the control treatment were stable throughout the experiment, whereas under the Irgarol treatment the corals showed gradual bleaching. The Irgarol treatment caused a rapid decrease in the slow decay DF component (10.1-60.0 s), while the fast decay DF component (0.1-10.0 s) decreased significantly after 6 d. The significant correlation between the latter values and the coral colour indicates that if the electron accumulation function of quinones QA and QB is compromised, corals will bleach. The present study will contribute to the understanding of the mechanism involved in bleaching of coral exposed to herbicides.

RevDate: 2020-06-19
CmpDate: 2020-06-19

Barth FG (2019)

One of the most fascinating stories in biology.

Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology, 205(3):281-284.

RevDate: 2020-06-18

Mohammed H, Jaiswal SK, Mohammed M, et al (2020)

Insights into nitrogen fixing traits and population structure analyses in cowpea (Vigna unguiculata L. Walp) accessions grown in Ghana.

Physiology and molecular biology of plants : an international journal of functional plant biology, 26(6):1263-1280.

With legumes, symbiotic N2 fixation can meet the species N demand and reduce the over-reliance on chemical fertilizers in tropical regions where N deficiency is a major factor limiting crop yields and increased agricultural sustainability. Therefore, to optimize the use of cowpea (Vigna unguiculata L. Walp) germplasm in effective breeding, evaluation of genetic diversity and quantification of N2 fixation are essential prerequisites. The aim of this study was to explore the level of diversity using SSR markers and N2-fixing traits in a set of cowpea germplasm grown in Ghana. We analysed 49 cowpea accessions collected from Northern Ghana using qualitative vegetative and N2 fixation traits, and simple sequence repeat (SSR) markers. Experimental field results revealed considerable morpho-physiological variation for plant growth habits, grain yield and symbiotic performance between and among the cowpea accessions. Results from both the 15N natural abundance and ureides in the xylem sap were able to descriminate between high and low levels of N2 fixation in cowpea accessions. Five subpopulations were identified within accessions inferred from STRUCTURE 2.3.4. A general linear model was used to assess the association of SSR markers with N2-fixing traits. There were significant (p ≤ 0.05) links between SSR markers and symbiosis-related traits such as nodule number, nodule dry weight, shoot dry weight, N-fixed, N derived from air (Ndfa), and relative uried-N (RU-N).

RevDate: 2020-06-18
CmpDate: 2020-06-18

Walker NS, Fernández R, Sneed JM, et al (2019)

Differential gene expression during substrate probing in larvae of the Caribbean coral Porites astreoides.

Molecular ecology, 28(22):4899-4913.

The transition from larva to adult is a critical step in the life history strategy of most marine animals. However, the genetic basis of this life history change remains poorly understood in many taxa, including most coral species. Recent evidence suggests that coral planula larvae undergo significant changes at the physiological and molecular levels throughout the development. To investigate this, we characterized differential gene expression (DGE) during the transition from planula to adult polyp in the abundant Caribbean reef-building coral Porites astreoides, that is from nonprobing to actively substrate-probing larva, a stage required for colony initiation. This period is crucial for the coral, because it demonstrates preparedness to locate appropriate substrata for settlement based on vital environmental cues. Through RNA-Seq, we identified 860 differentially expressed holobiont genes between probing and nonprobing larvae (p ≤ .01), the majority of which were upregulated in probing larvae. Surprisingly, differentially expressed genes of endosymbiotic dinoflagellate origin greatly outnumbered coral genes, compared with a nearly 1:1 ratio of coral-to-dinoflagellate gene representation in the holobiont transcriptome. This unanticipated result suggests that dinoflagellate endosymbionts may play a significant role in the transition from nonprobing to probing behaviour in dinoflagellate-rich larvae. Putative holobiont genes were largely involved in protein and nucleotide binding, metabolism and transport. Genes were also linked to environmental sensing and response and integral signalling pathways. Our results thus provide detailed insight into molecular changes prior to larval settlement and highlight the complex physiological and biochemical changes that occur in early transition stages from pelagic to benthic stages in corals, and perhaps more importantly, in their endosymbionts.

RevDate: 2020-06-18
CmpDate: 2020-06-18

Skelton J, Jusino MA, Carlson PS, et al (2019)

Relationships among wood-boring beetles, fungi, and the decomposition of forest biomass.

Molecular ecology, 28(22):4971-4986.

A prevailing paradigm in forest ecology is that wood-boring beetles facilitate wood decay and carbon cycling, but empirical tests have yielded mixed results. We experimentally determined the effects of wood borers on fungal community assembly and wood decay within pine trunks in the southeastern United States. Pine trunks were made either beetle-accessible or inaccessible. Fungal communities were compared using culturing and high-throughput amplicon sequencing (HTAS) of DNA and RNA. Prior to beetle infestation, living pines had diverse fungal endophyte communities. Endophytes were displaced by beetle-associated fungi in beetle-accessible trees, whereas some endophytes persisted as saprotrophs in beetle-excluded trees. Beetles increased fungal diversity several fold. Over forty taxa of Ascomycota were significantly associated with beetles, but beetles were not consistently associated with any known wood-decaying fungi. Instead, increasing ambrosia beetle infestations caused reduced decay, consistent with previous in vitro experiments that showed beetle-associated fungi reduce decay rates by competing with decay fungi. No effect of bark-inhabiting beetles on decay was detected. Platypodines carried significantly more fungal taxa than scolytines. Molecular results were validated by synthetic and biological mock communities and were consistent across methodologies. RNA sequencing confirmed that beetle-associated fungi were biologically active in the wood. Metabarcode sequencing of the LSU/28S marker recovered important fungal symbionts that were missed by ITS2, though community-level effects were similar between markers. In contrast to the current paradigm, our results indicate ambrosia beetles introduce diverse fungal communities that do not extensively decay wood, but instead reduce decay rates by competing with wood decay fungi.

RevDate: 2020-06-17

Valle LG, D Stoianova (2020)

First record of Harpellales, Orphellales (Kickxellomycotina) and Amoebidiales (Mesomycetozoea) from Bulgaria, including a new species of Glotzia.

MycoKeys, 67:55-80 pii:52055.

This paper presents the results obtained from a short survey performed in Bulgaria, southeast Europe, where the trichomycetes (sensu lato), an ecological group of arthropod gut endosymbionts, were previously completely unknown. The present study initiates the comprehension of these cryptic organisms, members of the Kickxellomycotina (Harpellales, Orphellales) and the Mesomycetozoea (Amoebidiales), in this Balkan country. Eighteen new geographic records for Bulgaria are reported, including 10 species of Harpellales, three species of Orphellales and five species of Amoebidiales. Within the Harpellales, the species Glotzia balkanensissp. nov. is described. This new species is most related to the rare species G. centroptili Gauthier ex Manier & Lichtw. and G. stenospora White & Lichtw., but is differentiated by spore and thallial characteristics. Photographs are provided and biogeographic implications of these records are discussed.

RevDate: 2020-06-17

Pirritano M, Zaburannyi N, Grosser K, et al (2020)

Dual-Seq reveals genome and transcriptome of Caedibacter taeniospiralis, obligate endosymbiont of Paramecium.

Scientific reports, 10(1):9727 pii:10.1038/s41598-020-65894-1.

Interest in host-symbiont interactions is continuously increasing, not only due to the growing recognition of the importance of microbiomes. Starting with the detection and description of novel symbionts, attention moves to the molecular consequences and innovations of symbioses. However, molecular analysis requires genomic data which is difficult to obtain from obligate intracellular and uncultivated bacteria. We report the identification of the Caedibacter genome, an obligate symbiont of the ciliate Paramecium. The infection does not only confer the host with the ability to kill other cells but also renders them immune against this effect. We obtained the C. taeniospiralis genome and transcriptome by dual-Seq of DNA and RNA from infected paramecia. Comparison of codon usage and expression level indicates that genes necessary for a specific trait of this symbiosis, i.e. the delivery of an unknown toxin, result from horizontal gene transfer hinting to the relevance of DNA transfer for acquiring new characters. Prediction of secreted proteins of Caedibacter as major agents of contact with the host implies, next to several toxin candidates, a rather uncharacterized secretome which appears to be highly adapted to this symbiosis. Our data provides new insights into the molecular establishment and evolution of this obligate symbiosis and for the pathway characterization of toxicity and immunity.

RevDate: 2020-06-17

Xing YM, Zhao MM, Guo LC, et al (2020)

Identification and expression of DoCCaMK during Sebacina sp. symbiosis of Dendrobium officinale.

Scientific reports, 10(1):9733 pii:10.1038/s41598-020-66616-3.

Dendrobium officinale Kimura et Migo is a famous precious medicinal plant in China. Seed and seedling were cultivated with the mycorrhizal fungus Sebacina sp. CCaMK was initially cloned from D. officinale based on a SSH cDNA library of symbiotically germinated seeds with Sebacina sp. Phylogenetic analysis was performed among DoCCaMK and other CCaMKs. The particle bombardment technique was used to visualize DoCCaMK-GFP. qRT-PCR and western blot analysis were conducted to determine the tissue expression patterns of DoCCaMK with (SGS) and without (UGS) Sebacina sp. Furthermore, the effect of KN-93 on CCaMK expression was also examined. Using NMT the net Ca2+ fluxes and the CCaMK concentration were measured during D. officinale seed germination. DoCCaMK had the highest homology with Lilium longiflorum CCaMK. The DoCCaMK-GFP protein localized in the nucleus and cell membrane. CCaMK expression was significantly upregulated after symbiosis with Sebacina sp. KN-93 could be used as an inhibitor of CCaMK to inhibit D. officinale seed germination. Ca2+ influx and the concentration of the CCaMK in the SGS group was significantly more than that of the UGS group. The characterization of CCaMK provides certain genetic evidence for the involvement of this gene during seed germination and mycorrhizal cultivation in D. officinale.

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ESP Quick Facts

ESP Origins

In the early 1990's, Robert Robbins was a faculty member at Johns Hopkins, where he directed the informatics core of GDB — the human gene-mapping database of the international human genome project. To share papers with colleagues around the world, he set up a small paper-sharing section on his personal web page. This small project evolved into The Electronic Scholarly Publishing Project.

ESP Support

In 1995, Robbins became the VP/IT of the Fred Hutchinson Cancer Research Center in Seattle, WA. Soon after arriving in Seattle, Robbins secured funding, through the ELSI component of the US Human Genome Project, to create the original ESP.ORG web site, with the formal goal of providing free, world-wide access to the literature of classical genetics.

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Although the methods of molecular biology can seem almost magical to the uninitiated, the original techniques of classical genetics are readily appreciated by one and all: cross individuals that differ in some inherited trait, collect all of the progeny, score their attributes, and propose mechanisms to explain the patterns of inheritance observed.

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In reading the early works of classical genetics, one is drawn, almost inexorably, into ever more complex models, until molecular explanations begin to seem both necessary and natural. At that point, the tools for understanding genome research are at hand. Assisting readers reach this point was the original goal of The Electronic Scholarly Publishing Project.

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Usage of the site grew rapidly and has remained high. Faculty began to use the site for their assigned readings. Other on-line publishers, ranging from The New York Times to Nature referenced ESP materials in their own publications. Nobel laureates (e.g., Joshua Lederberg) regularly used the site and even wrote to suggest changes and improvements.

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When the site began, no journals were making their early content available in digital format. As a result, ESP was obliged to digitize classic literature before it could be made available. For many important papers — such as Mendel's original paper or the first genetic map — ESP had to produce entirely new typeset versions of the works, if they were to be available in a high-quality format.

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With the development of methods for adding typeset side notes to PDF files, the ESP project now plans to add annotated versions of some classical papers to its holdings. We also plan to add new reference and pedagogical material. We have already started providing regularly updated, comprehensive bibliographies to the ESP.ORG site.

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