Plant microbiome studies
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Salicylic acid modulates colonization of the root microbiome by specific bacterial taxa

Salicylic acid modulates colonization of the root microbiome by specific bacterial taxa | Plant microbiome studies | Scoop.it
Immune systems distinguish “self” from “nonself” to maintain homeostasis and must differentially gate access to allow colonization by potentially beneficial, nonpathogenic microbes. Plant roots grow within extremely diverse soil microbial communities but assemble a taxonomically limited root-associated microbiome. We grew isogenic Arabidopsis thaliana mutants with altered immune systems in a wild soil and also in recolonization experiments with a synthetic bacterial community. We established that biosynthesis of, and signaling dependent on, the foliar defense phytohormone salicylic acid is required to assemble a normal root microbiome. Salicylic acid modulates colonization of the root by specific bacterial families. Thus, plant immune signaling drives selection from the available microbial communities to sculpt the root microbiome.
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Interaction and signalling between a cosmopolitan phytoplankton and associated bacteria : Nature : Nature Publishing Group

Interaction and signalling between a cosmopolitan phytoplankton and associated bacteria : Nature : Nature Publishing Group | Plant microbiome studies | Scoop.it
Interactions between primary producers and bacteria impact the physiology of both partners, alter the chemistry of their environment, and shape ecosystem diversity1, 2. In marine ecosystems, these interactions are difficult to study partly because the major photosynthetic organisms are microscopic, unicellular phytoplankton3. Coastal phytoplankton communities are dominated by diatoms, which generate approximately 40% of marine primary production and form the base of many marine food webs4. Diatoms co-occur with specific bacterial taxa3, but the mechanisms of potential interactions are mostly unknown. Here we tease apart a bacterial consortium associated with a globally distributed diatom and find that a Sulfitobacter species promotes diatom cell division via secretion of the hormone indole-3-acetic acid, synthesized by the bacterium using both diatom-secreted and endogenous tryptophan. Indole-3-acetic acid and tryptophan serve as signalling molecules that are part of a complex exchange of nutrients, including diatom-excreted organosulfur molecules and bacterial-excreted ammonia. The potential prevalence of this mode of signalling in the oceans is corroborated by metabolite and metatranscriptome analyses that show widespread indole-3-acetic acid production by Sulfitobacter-related bacteria, particularly in coastal environments. Our study expands on the emerging recognition that marine microbial communities are part of tightly connected networks by providing evidence that these interactions are mediated through production and exchange of infochemicals.
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Metabolic dependencies drive species co-occurrence in diverse microbial communities

Metabolic dependencies drive species co-occurrence in diverse microbial communities | Plant microbiome studies | Scoop.it

Although metabolic interactions have long been implicated in the assembly of microbial communities, their general prevalence has remained largely unknown. In this study, we systematically survey, by using a metabolic modeling approach, the extent of resource competition and metabolic cross-feeding in over 800 microbial communities from diverse habitats. We show that interspecies metabolic exchanges are widespread in natural communities, and that such exchanges can provide group advantage under nutrient-poor conditions. Our results highlight metabolic dependencies as a major driver of species co-occurrence. The presented methodology and mechanistic insights have broad implications for understanding compositional variation in natural communities as well as for facilitating the design of synthetic microbial communities.


Via Kemen Lab, Stéphane Hacquard
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Hsiao-Han Lin's curator insight, May 5, 2015 9:51 PM

microbe are not the same, and they communicate and exchange

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The ISME J: Stability and succession of the rhizosphere microbiota depends upon plant type and soil composition

The ISME J: Stability and succession of the rhizosphere microbiota depends upon plant type and soil composition | Plant microbiome studies | Scoop.it

We examined succession of the rhizosphere microbiota of three model plants (Arabidopsis, Medicago and Brachypodium) in compost and sand and three crops (Brassica, Pisum and Triticum) in compost alone. We used serial inoculation of 24 independent replicate microcosms over three plant generations for each plant/soil combination. Stochastic variation between replicates was surprisingly weak and by the third generation, replicate microcosms for each plant had communities that were very similar to each other but different to those of other plants or unplanted soil. Microbiota diversity remained high in compost, but declined drastically in sand, with bacterial opportunists and putative autotrophs becoming dominant. These dramatic differences indicate that many microbes cannot thrive on plant exudates alone and presumably also require carbon sources and/or nutrients from soil. Arabidopsis had the weakest influence on its microbiota and in compost replicate microcosms converged on three alternative community compositions rather than a single distinctive community. Organisms selected in rhizospheres can have positive or negative effects. Two abundant bacteria are shown to promote plant growth, but in Brassica the pathogen Olpidium brassicae came to dominate the fungal community. So plants exert strong selection on the rhizosphere microbiota but soil composition is critical to its stability. microbial succession/ plant–microbe interactions/rhizosphere microbiota/selection


Via Stéphane Hacquard
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The ISME Journal - Metatranscriptomic census of active protists in soils

The ISME Journal - Metatranscriptomic census of active protists in soils | Plant microbiome studies | Scoop.it
The high numbers and diversity of protists in soil systems have long been presumed, but their true diversity and community composition have remained largely concealed. Traditional cultivation-based methods miss a majority of taxa, whereas molecular barcoding approaches employing PCR introduce significant biases in reported community composition of soil protists. Here, we applied a metatranscriptomic approach to assess the protist community in 12 mineral and organic soil samples from different vegetation types and climatic zones using small subunit ribosomal RNA transcripts as marker. We detected a broad diversity of soil protists spanning across all known eukaryotic supergroups and revealed a strikingly different community composition than shown before. Protist communities differed strongly between sites, with Rhizaria and Amoebozoa dominating in forest and grassland soils, while Alveolata were most abundant in peat soils. The Amoebozoa were comprised of Tubulinea, followed with decreasing abundance by Discosea, Variosea and Mycetozoa. Transcripts of Oomycetes, Apicomplexa and Ichthyosporea suggest soil as reservoir of parasitic protist taxa. Further, Foraminifera and Choanoflagellida were ubiquitously detected, showing that these typically marine and freshwater protists are autochthonous members of the soil microbiota. To the best of our knowledge, this metatranscriptomic study provides the most comprehensive picture of active protist communities in soils to date, which is essential to target the ecological roles of protists in the complex soil system.
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Peer J: Wild plant species growing closely connected in a subalpine meadow host distinct root-associated bacterial communities

Peer J: Wild plant species growing closely connected in a subalpine meadow host distinct root-associated bacterial communities | Plant microbiome studies | Scoop.it
Plant roots are known to harbor large and diverse communities of bacteria. It has been suggested that plant identity can structure these root-associated communities, but few studies have specifically assessed how the composition of root microbiota varies within and between plant species growing under natural conditions. We assessed the community composition of endophytic and epiphytic bacteria through high throughput sequencing using 16S rDNA derived from root tissues collected from a population of a wild, clonal plant (Orange hawkweed–Pilosella aurantiaca) as well as two neighboring plant species (Oxeye daisy–Leucanthemum vulgare and Alsike clover–Trifolium hybridum). Our first goal was to determine if plant species growing in close proximity, under similar environmental conditions, still hosted unique root microbiota. Our results showed that plants of different species host distinct bacterial communities in their roots. In terms of community composition, Betaproteobacteria (especially the family Oxalobacteraceae) were found to dominate in the root microbiota of L. vulgare and T. hybridum samples, whereas the root microbiota of P. aurantiaca had a more heterogeneous distribution of bacterial abundances where Gammaproteobacteria and Acidobacteria occupied a larger portion of the community. We also explored the extent of individual variance within each plant species investigated, and found that in the plant species thought to have the least genetic variance among individuals (P. aurantiaca) still hosted just as diverse microbial communities. Whether all plant species host their own distinct root microbiota and plants more closely related to each other share more similar bacterial communities still remains to be fully explored, but among the plants examined in this experiment there was no trend that the two species belonging to the same family shared more similarities in terms of bacterial community composition.

Via Stéphane Hacquard
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Genotype-Specific Variation in the Structure of Root Fungal Communities Is Related to Chickpea Plant Productivity

Genotype-Specific Variation in the Structure of Root Fungal Communities Is Related to Chickpea Plant Productivity | Plant microbiome studies | Scoop.it
Increasing evidence supports the existence of variations in the association of plant roots with symbiotic fungi that can improve plant growth and inhibit pathogens. However, it is unclear whether intraspecific variations in the symbiosis exist among plant cultivars and if they can be used to improve crop productivity. In this study, we determined genotype-specific variations in the association of chickpea roots with soil fungal communities and evaluated the effect of root mycota on crop productivity. A 2-year field experiment was conducted in southwestern Saskatchewan, the central zone of the chickpea growing region of the Canadian prairie. The effects of 13 cultivars of chickpea, comprising a wide range of phenotypes and genotypes, were tested on the structure of root-associated fungal communities based on internal transcribed spacer (ITS) and 18S rRNA gene markers using 454 amplicon pyrosequencing. Chickpea cultivar significantly influenced the structure of the root fungal community. The magnitude of the effect varied with the genotypes evaluated, and effects were consistent across years. For example, the roots of CDC Corrine, CDC Cory, and CDC Anna hosted the highest fungal diversity and CDC Alma and CDC Xena the lowest. Fusarium sp. was dominant in chickpea roots but was less abundant in CDC Corrine than the other cultivars. A bioassay showed that certain of these fungal taxa, including Fusarium species, can reduce the productivity of chickpea, whereas Trichoderma harzianum can increase chickpea productivity. The large variation in the profile of chickpea root mycota, which included growth-promoting and -inhibiting species, supports the possibility of improving the productivity of chickpea by improving its root mycota in chickpea genetic improvement programs using traditional breeding techniques.
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Scientific Reports: Microbial communities on flower surfaces act as signatures of pollinator visitation

Scientific Reports: Microbial communities on flower surfaces act as signatures of pollinator visitation | Plant microbiome studies | Scoop.it
Microbes are easily dispersed from one place to another, and immigrant microbes might contain information about the environments from which they came. We hypothesized that part of the microbial community on a flower's surface is transferred there from insect body surfaces and that this community can provide information to identify potential pollinator insects of that plant. We collected insect samples from the field, and found that an insect individual harbored an average of 12.2 [times] 105 microbial cells on its surface. A laboratory experiment showed that the microbial community composition on a flower surface changed after contact with an insect, suggesting that microbes are transferred from the insect to the flower. Comparison of the microbial fingerprint approach and direct visual observation under field condition suggested that the microbial community on a flower surface could to some extent indicate the structure of plant-pollinator interactions. In conclusion, species-specific insect microbial communities specific to insect species can be transferred from an insect body to a flower surface, and these microbes can serve as a [ldquo]fingerprint[rdquo] of the insect species, especially for large-bodied insects. Dispersal of microbes is a ubiquitous phenomenon that has unexpected and novel applications in many fields and disciplines.

Via Stéphane Hacquard
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PNAS: Disentangling mechanisms that mediate the balance between stochastic and deterministic processes in microbial succession

Ecological succession and the balance between stochastic and deterministic processes are two major themes within microbial ecology, but these conceptual domains have mostly developed independent of each other. Here we provide a framework that integrates shifts in community assembly processes with microbial primary succession to better understand mechanisms governing the stochastic/deterministic balance. Synthesizing previous work, we devised a conceptual model that links ecosystem development to alternative hypotheses related to shifts in ecological assembly processes. Conceptual model hypotheses were tested by coupling spatiotemporal data on soil bacterial communities with environmental conditions in a salt marsh chronosequence spanning 105 years of succession. Analyses within successional stages showed community composition to be initially governed by stochasticity, but as succession proceeded, there was a progressive increase in deterministic selection correlated with increasing sodium concentration. Analyses of community turnover among successional stages—which provide a larger spatiotemporal scale relative to within stage analyses—revealed that changes in the concentration of soil organic matter were the main predictor of the type and relative influence of determinism. Taken together, these results suggest scale-dependency in the mechanisms underlying selection. To better understand mechanisms governing these patterns, we developed an ecological simulation model that revealed how changes in selective environments cause shifts in the stochastic/deterministic balance. Finally, we propose an extended—and experimentally testable—conceptual model integrating ecological assembly processes with primary and secondary succession. This framework provides a priori hypotheses for future experiments, thereby facilitating a systematic approach to understand assembly and succession in microbial communities across ecosystems.


Via Stéphane Hacquard
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The Diverse Microbiome of the Hunter-Gatherer : Nature

The Diverse Microbiome of the Hunter-Gatherer : Nature | Plant microbiome studies | Scoop.it
We tend to forget that modern humanity is largely sheltered from the last vestiges of wild untamed Earth and that our way of life bears little resemblance to how our ancestors lived during 90 percent of human history. We have lost nearly all trace of these former selves—and, worse, have marginalized the few remaining humans who retain their hunter-gatherer identity. In Tanzania, tribes of wandering foragers called the Hadza, who have lived for thousands of years in the East African Rift Valley ecosystem, tell us an immense and precious story about how humans, together with their microbial evolutionary partners, are adapted to live and thrive in a complex natural environment.

Via Francis Martin, Stéphane Hacquard
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Improved pipeline for reducing erroneous identification by 16S rRNA sequences using the Illumina MiSeq platform - Springer

Improved pipeline for reducing erroneous identification by 16S rRNA sequences using the Illumina MiSeq platform - Springer | Plant microbiome studies | Scoop.it

The cost of DNA sequencing has decreased due to advancements in Next Generation Sequencing. The number of sequences obtained from the Illumina platform is large, use of this platform can reduce costs more than the 454 pyrosequencer. However, the Illumina platform has other challenges, including bioinformatics analysis of large numbers of sequences and the need to reduce erroneous nucleotides generated at the 3′-ends of the sequences. These erroneous sequences can lead to errors in analysis of microbial communities. Therefore, correction of these erroneous sequences is necessary for accurate taxonomic identification. Several studies that have used the Illumina platform to perform metagenomic analyses proposed curating pipelines to increase accuracy. In this study, we evaluated the likelihood of obtaining an erroneous microbial composition using the MiSeq 250 bp paired sequence platform and improved the pipeline to reduce erroneous identifications. We compared different sequencing conditions by varying the percentage of control phiX added, the concentration of the sequencing library, and the 16S rRNA gene target region using a mock community sample composed of known sequences. Our recommended method corrected erroneous nucleotides and improved identification accuracy. Overall, 99.5% of the total reads shared 95% similarity with the corresponding template sequences and 93.6% of the total reads shared over 97% similarity. This indicated that the MiSeq platform can be used to analyze microbial communities at the genus level with high accuracy. The improved analysis method recommended in this study can be applied to amplicon studies in various environments using high-throughput reads generated on the MiSeq platform.


Via Stéphane Hacquard
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MPMI: The plant microbiome at work | microbial ...

MPMI: The plant microbiome at work | microbial ... | Plant microbiome studies | Scoop.it
Plants host distinct microbial communities on and inside their tissues designated the plant microbiota.
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The ISME Journal - Interpreting 16S metagenomic data without clustering to achieve sub-OTU resolution

The ISME Journal - Interpreting 16S metagenomic data without clustering to achieve sub-OTU resolution | Plant microbiome studies | Scoop.it
The ISME Journal: Multidisciplinary Journal of Microbial Ecology is the official Journal of the International Society for Microbial Ecology, publishing high-quality, original research papers, short communications, commentary articles and reviews in...

Via Jean-Michel Ané, Stéphane Hacquard
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Impact of plant domestication on rhizosphere microbiome assembly and functions - Online First - Springer

Impact of plant domestication on rhizosphere microbiome assembly and functions - Online First - Springer | Plant microbiome studies | Scoop.it
"Impact of plant domestication on rhizosphere microbiome assembly and functions - Online First - Springer" #feedly http://t.co/i7ynAwAG6T
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Structure and function of the global ocean microbiome

Structure and function of the global ocean microbiome | Plant microbiome studies | Scoop.it
Microbes are dominant drivers of biogeochemical processes, yet drawing a global picture of functional diversity, microbial community structure, and their ecological determinants remains a grand challenge. We analyzed 7.2 terabases of metagenomic data from 243 Tara Oceans samples from 68 locations in epipelagic and mesopelagic waters across the globe to generate an ocean microbial reference gene catalog with >40 million nonredundant, mostly novel sequences from viruses, prokaryotes, and picoeukaryotes. Using 139 prokaryote-enriched samples, containing >35,000 species, we show vertical stratification with epipelagic community composition mostly driven by temperature rather than other environmental factors or geography. We identify ocean microbial core functionality and reveal that >73% of its abundance is shared with the human gut microbiome despite the physicochemical differences between these two ecosystems.

Via Francis Martin, Stéphane Hacquard
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phylogeo: an R package for geographic analysis and visualization of microbiome data.

phylogeo: an R package for geographic analysis and visualization of microbiome data. | Plant microbiome studies | Scoop.it
RT @DrJCThrash: phylogeo: an R package for geographic analysis and visualization of microbiome data. http://t.co/3vlCmUYyLR

Via Mel Melendrez-Vallard
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The ISME Journal - The coral core microbiome identifies rare bacterial taxa as ubiquitous endosymbionts

The ISME Journal - The coral core microbiome identifies rare bacterial taxa as ubiquitous endosymbionts | Plant microbiome studies | Scoop.it
Despite being one of the simplest metazoans, corals harbor some of the most highly diverse and abundant microbial communities. Differentiating core, symbiotic bacteria from this diverse host-associated consortium is essential for characterizing the functional contributions of bacteria but has not been possible yet. Here we characterize the coral core microbiome and demonstrate clear phylogenetic and functional divisions between the micro-scale, niche habitats within the coral host. In doing so, we discover seven distinct bacterial phylotypes that are universal to the core microbiome of coral species, separated by thousands of kilometres of oceans. The two most abundant phylotypes are co-localized specifically with the corals’ endosymbiotic algae and symbiont-containing host cells. These bacterial symbioses likely facilitate the success of the dinoflagellate endosymbiosis with corals in diverse environmental regimes.
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Rescooped by Nina Dombrowski from Plant-Microbe Symbiosis
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The Soil Microbiome Influences Grapevine-Associated Microbiota

Grapevine is a well-studied, economically relevant crop, whose associated bacteria could influence its organoleptic properties. In this study, the spatial and temporal dynamics of the bacterial communities associated with grapevine organs (leaves, flowers, grapes, and roots) and soils were characterized over two growing seasons to determine the influence of vine cultivar, edaphic parameters, vine developmental stage (dormancy, flowering, preharvest), and vineyard. Belowground bacterial communities differed significantly from those aboveground, and yet the communities associated with leaves, flowers, and grapes shared a greater proportion of taxa with soil communities than with each other, suggesting that soil may serve as a bacterial reservoir. A subset of soil microorganisms, including root colonizers significantly enriched in plant growth-promoting bacteria and related functional genes, were selected by the grapevine. In addition to plant selective pressure, the structure of soil and root microbiota was significantly influenced by soil pH and C:N ratio, and changes in leaf- and grape-associated microbiota were correlated with soil carbon and showed interannual variation even at small spatial scales. Diazotrophic bacteria, e.g., Rhizobiaceae and Bradyrhizobium spp., were significantly more abundant in soil samples and root samples of specific vineyards. Vine-associated microbial assemblages were influenced by myriad factors that shape their composition and structure, but the majority of organ-associated taxa originated in the soil, and their distribution reflected the influence of highly localized biogeographic factors and vineyard management.

IMPORTANCE Vine-associated bacterial communities may play specific roles in the productivity and disease resistance of their host plant. Also, the bacterial communities on grapes have the potential to influence the organoleptic properties of the wine, contributing to a regional terroir. Understanding that factors that influence these bacteria may provide insights into management practices to shape and craft individual wine properties. We show that soil serves as a key source of vine-associated bacteria and that edaphic factors and vineyard-specific properties can influence the native grapevine microbiome preharvest.

Via Jean-Michel Ané
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Jean-Michel Ané's curator insight, March 25, 2015 6:41 PM

It always ticks me off when people claim the presence of "diazotrophic bacteria" based on that kind of study... They have no idea if these bacteria fix nitrogen and, in fact, it is very likely that they don't in the grape rhizoshere. 

Stijn Spaepen's comment, March 26, 2015 1:09 PM
Totally agree with your comment, Jean-Michel!
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Improving microbial fitness in the mammalian gut by in vivo temporal functional metagenomics

Improving microbial fitness in the mammalian gut by in vivo temporal functional metagenomics | Plant microbiome studies | Scoop.it
Elucidating functions of commensal microbial genes in the mammalian gut is challenging because many commensals are recalcitrant to laboratory cultivation and genetic manipulation. We present Temporal FUnctional Metagenomics sequencing (TFUMseq), a platform to functionally mine bacterial genomes for genes that contribute to fitness of commensal bacteria in vivo. Our approach uses metagenomic DNA to construct large‐scale heterologous expression libraries that are tracked over time in vivo by deep sequencing and computational methods. To demonstrate our approach, we built a TFUMseq plasmid library using the gut commensal Bacteroides thetaiotaomicron (Bt) and introduced Escherichia coli carrying this library into germfree mice. Population dynamics of library clones revealed Bt genes conferring significant fitness advantages in E. coli over time, including carbohydrate utilization genes, with a Bt galactokinase central to early colonization, and subsequent dominance by a Bt glycoside hydrolase enabling sucrose metabolism coupled with co‐evolution of the plasmid library and E. coli genome driving increased galactose utilization. Our findings highlight the utility of functional metagenomics for engineering commensal bacteria with improved properties, including expanded colonization capabilities in vivo.
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Molecular Plant-Microbe Interactions Journal - 28(3):274 - Abstract

Molecular Plant-Microbe Interactions Journal - 28(3):274 - Abstract | Plant microbiome studies | Scoop.it
The leaf microbiome is influenced by both biotic and abiotic factors. Currently, we know little about the relative importance of these factors in determining microbiota composition and dynamics. To explore this issue, we collected weekly leaf samples over a 98-day growing season from multiple cultivars of common bean, soybean, and canola planted at three locations in Ontario, Canada, and performed Illumina-based microbiome analysis. We find that the leaf microbiota at the beginning of the season is very strongly influenced by the soil microbiota but, as the season progresses, it differentiates, becomes significantly less diverse, and transitions to having a greater proportion of leaf-specific taxa that are shared among all samples. A phylogenetic investigation of communities by reconstruction of unobserved states imputation of microbiome function inferred from the taxonomic data found significant differences between the soil and leaf microbiome, with a significant enrichment of motility gene categories in the former and metabolic gene categories in the latter. A network co-occurrence analysis identified two highly connected clusters as well as subclusters of putative pathogens and growth-promoting bacteria. These data reveal some of the complex ecological dynamics that occur in microbial communities over the course of a growing season and highlight the importance of community succession.
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Multi-omics of permafrost, active layer and thermokarst bog soil microbiomes : Nature : Nature Publishing Group

Multi-omics of permafrost, active layer and thermokarst bog soil microbiomes : Nature : Nature Publishing Group | Plant microbiome studies | Scoop.it
Over 20% of Earth/'s terrestrial surface is underlain by permafrost with vast stores of carbon that, once thawed, may represent the largest future transfer of carbon from the biosphere to the atmosphere. This process is largely dependent on microbial responses, but we know little about microbial activity in intact, let alone in thawing, permafrost. Molecular approaches have recently revealed the identities and functional gene composition of microorganisms in some permafrost soils and a rapid shift in functional gene composition during short-term thaw experiments. However, the fate of permafrost carbon depends on climatic, hydrological and microbial responses to thaw at decadal scales. Here we use the combination of several molecular /`omics/' approaches to determine the phylogenetic composition of the microbial communities, including several draft genomes of novel species, their functional potential and activity in soils representing different states of thaw: intact permafrost, seasonally thawed active layer and thermokarst bog. The multi-omics strategy reveals a good correlation of process rates to omics data for dominant processes, such as methanogenesis in the bog, as well as novel survival strategies for potentially active microbes in permafrost.

Via Francis Martin
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Structure and Function of the Bacterial Root Microbiota in Wild and Domesticated Barley: Cell Host & Microbe

Structure and Function of the Bacterial Root Microbiota in Wild and Domesticated Barley: Cell Host & Microbe | Plant microbiome studies | Scoop.it
The microbial communities inhabiting the root interior of healthy plants, as well as the rhizosphere, which consists of soil particles firmly attached to roots, engage in symbiotic associations with their host. To investigate the structural and functional diversification among these communities, we employed a combination of 16S rRNA gene profiling and shotgun metagenome analysis of the microbiota associated with wild and domesticated accessions of barley (Hordeum vulgare). Bacterial families Comamonadaceae, Flavobacteriaceae, and Rhizobiaceae dominate the barley root-enriched microbiota. Host genotype has a small, but significant, effect on the diversity of root-associated bacterial communities, possibly representing a footprint of barley domestication. Traits related to pathogenesis, secretion, phage interactions, and nutrient mobilization are enriched in the barley root-associated microbiota. Strikingly, protein families assigned to these same traits showed evidence of positive selection. Our results indicate that the combined action of microbe-microbe and host-microbe interactions drives microbiota differentiation at the root-soil interface.
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Greater than the sum of their parts: characterizing plant microbiomes at the community-level

Greater than the sum of their parts: characterizing plant microbiomes at the community-level | Plant microbiome studies | Scoop.it

Highlights

•Each plant microbiome type differs predictably with its surrounding environment.

 

•While most soil microbes are dormant, the bulk of rhizospheric microbes are active.

 

•Plant microbiomes contribute to plant health by multiple mechanisms simultaneously.


Via Jean-Michel Ané
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Water Content Differences Have Stronger Effects than Plant Functional Groups on Soil Bacteria in a Steppe Ecosystem

Water Content Differences Have Stronger Effects than Plant Functional Groups on Soil Bacteria in a Steppe Ecosystem | Plant microbiome studies | Scoop.it

Many investigations across natural and artificial plant diversity gradients have reported that both soil physicochemical factors and plant community composition affect soil microbial communities. To test the effect of plant diversity loss on soil bacterial communities, we conducted a five-year plant functional group removal experiment in a steppe ecosystem in Inner Mongolia (China). We found that the number and composition type of plant functional groups had no effect on bacterial diversity and community composition, or on the relative abundance of major taxa. In contrast, bacterial community patterns were significantly structured by soil water content differences among plots. Our results support researches that suggest that water availability is the key factor structuring soil bacterial communities in this semi-arid ecosystem


Via Christophe Jacquet
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New Phytol: The soil microbial community predicts the importance of plant traits in plant–soil feedback

New Phytol: The soil microbial community predicts the importance of plant traits in plant–soil feedback | Plant microbiome studies | Scoop.it

Reciprocal interaction between plant and soil (plant–soil feedback, PSF) can determine plant community structure. Understanding which traits control interspecific variation of PSF strength is crucial for plant ecology. Studies have highlighted either plant-mediated nutrient cycling (litter-mediated PSF) or plant–microbe interaction (microbial-mediated PSF) as important PSF mechanisms, each attributing PSF variation to different traits. However, this separation neglects the complex indirect interactions between the two mechanisms.
We developed a model coupling litter- and microbial-mediated PSFs to identify the relative importance of traits in controlling PSF strength, and its dependency on the composition of root-associated microbes (i.e. pathogens and/or mycorrhizal fungi).
Results showed that although plant carbon: nitrogen (C : N) ratio and microbial nutrient acquisition traits were consistently important, the importance of litter decomposability varied. Litter decomposability was not a major PSF determinant when pathogens are present. However, its importance increased with the relative abundance of mycorrhizal fungi as nutrient released from the mycorrhizal-enhanced litter production to the nutrient-depleted soils result in synergistic increase of soil nutrient and mycorrhizal abundance. Data compiled from empirical studies also supported our predictions.
We propose that the importance of litter decomposability depends on the composition of root-associated microbes. Our results provide new perspectives in plant invasion and trait-based ecology.


Via Stéphane Hacquard
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