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Rescooped by David Biate from Plant-Microbe Symbioses
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The composition of arbuscular mycorrhizal fungal communities differs among the roots, spores and extraradical mycelia associated with five Mediterranean plant species

The composition of arbuscular mycorrhizal fungal communities differs among the roots, spores and extraradical mycelia associated with five Mediterranean plant species | Microbes | Scoop.it
Arbuscular mycorrhizal fungi (AMF) are essential constituents of most terrestrial ecosystems. AMF species differ in terms of propagation strategies and the major propagules they form. This study compared the AMF community composition of different propagule fractions— colonised roots, spores and extraradical mycelium (ERM)—associated with five Mediterranean plant species in Sierra de Baza Natural Park (Granada, Spain). AMF were identified using 454 pyrosequencing of the SSU rRNA gene. A total of 96 AMF phylogroups (virtual taxa, VT) were detected in the study site, including 31 novel VT. After per-sample sequencing depth standardisation, 71 VT were recorded from plant roots, and 47 from each of the spore and ERM fractions. AMF communities differed significantly among the propagule fractions, and the root-colonizing fraction differed among host plant species. Indicator VT were detected for the root (13 Glomus VTs), spore (Paraglomus VT281, VT336, Pacispora VT284) and ERM (Diversispora VT62) fractions. This study provides detailed evidence from a natural system that AMF taxa are differentially allocated among soil mycelium, soil spores and colonized root propagules. This has important implications for interpreting AMF diversity surveys and designing applications of AMF in vegetation restoration.

Via Jean-Michel Ané
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Rescooped by David Biate from Plant-Microbe Symbioses
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Multiple steps control immunity during the intracellular accommodation of rhizobia

Multiple steps control immunity during the intracellular accommodation of rhizobia | Microbes | Scoop.it
Medicago truncatula belongs to the legume family and forms symbiotic associations with nitrogen fixing bacteria, the rhizobia. During these interactions, the plants develop root nodules in which bacteria invade the plant cells and fix nitrogen for the benefit of the plant. Despite massive infection, legume nodules do not develop visible defence reactions, suggesting a special immune status of these organs. Some factors influencing rhizobium maintenance within the plant cells have been previously identified, such as the M. truncatula NCR peptides whose toxic effects are reduced by the bacterial protein BacA. In addition, DNF2, SymCRK, and RSD are M. truncatula genes required to avoid rhizobial death within the symbiotic cells. DNF2 and SymCRK are essential to prevent defence-like reactions in nodules after bacteria internalization into the symbiotic cells. Herein, we used a combination of genetics, histology and molecular biology approaches to investigate the relationship between the factors preventing bacterial death in the nodule cells. We show that the RSD gene is also required to repress plant defences in nodules. Upon inoculation with the bacA mutant, defence responses are observed only in the dnf2 mutant and not in the symCRK and rsd mutants. In addition, our data suggest that lack of nitrogen fixation by the bacterial partner triggers bacterial death in nodule cells after bacteroid differentiation. Together our data indicate that, after internalization, at least four independent mechanisms prevent bacterial death in the plant cell. These mechanisms involve successively: DNF2, BacA, SymCRK/RSD and bacterial ability to fix nitrogen.

Via Jean-Michel Ané
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Rescooped by David Biate from MycorWeb Plant-Microbe Interactions
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Botanical brilliance

Botanical brilliance | Microbes | Scoop.it

In Plant Behaviour and Intelligence, Anthony Trewavas challenges us to leave behind our prejudices and view the world from a plant's perspective. Plants, he argues, behave on their own time scale, with their own unique physiology, and solve problems that are equally as complex as those confronting animals. This book represents a treasure trove of fascinating case studies and has the potential to serve as an important resource for plant physiologists and behavioral ecologists alike.


Via Francis Martin
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Rescooped by David Biate from Plant-Microbe Symbioses
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Taxonomy of rhizobia and agrobacteria from the Rhizobiaceae family in light of genomics

Taxonomy of rhizobia and agrobacteria from the Rhizobiaceae family in light of genomics | Microbes | Scoop.it
Phylogenomic analyses showed two major superclades within the family Rhizobiaceae that corresponded to the Rhizobium/Agrobacterium and Shinella/Ensifer groups. Within the Rhizobium/Agrobacterium group, four highly supported clades were evident that could correspond to distinct genera. The Shinella/Ensifer group encompassed not only the genera Shinella and Ensifer but also a separate clade containing the type strain of Rhizobium giardinii. Ensifer adhaerens (Casida AT) was an outlier within its group, separated from the rest of the Ensifer strains. The phylogenomic analysis presented provided support for the revival of Allorhizobium as a bona fide genus within the Rhizobiaceae, the distinctiveness of Agrobacterium and the recently proposed Neorhizobium genus, and suggested that R. giardinii may be transferred to a novel genus. Genomics has provided data for defining bacterial-species limits from estimates of average nucleotide identity (ANI) and in silico DNA–DNA hybridization (DDH). ANI reference values are becoming the gold standard in rhizobial taxonomy and are being used to recognize novel rhizobial lineages and species that seem to be biologically coherent, as shown in this study.

Via Jean-Michel Ané
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Rescooped by David Biate from Plant-Microbe Symbioses
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Plant coevolution: evidences and new challenges

Coevolution has been defined as the reciprocal genetic change in interacting species owing to natural selection imposed by each on the other. The process of coevolution between plants and the surrounding biota – including viruses, fungi, bacteria, nematodes, insects, and mammals – is considered by many biologists to have generated much of the earth's biological diversity. While much of the discussion on plant coevolution focuses on single plant–enemy interactions, a wide array of other micro and macro coevolutive processes co-occur in the same individual plant, posing the question whether we should talk about plant coevolutions. In this review article, I begin by briefly discussing the framework of coevolution theory and explore the complexities of studying coevolution in natural conditions. Then I analyze the difference between plants, microbes and animal coevolution, by exploring the above- and below-ground behaviors.

Via Jean-Michel Ané
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Three explanations for biodiversity hotspots: small range size, geographical overlap and time for species accumulation. An Australian case study - Cook - 2014 - New Phytologist - Wiley Online Library

Three explanations for biodiversity hotspots: small range size, geographical overlap and time for species accumulation. An Australian case study - Cook - 2014 - New Phytologist - Wiley Online Library | Microbes | Scoop.it
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Rescooped by David Biate from Plant-Microbe Symbioses
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Mycorrhizal ecology and evolution: the past, the present, and the future

Mycorrhizal ecology and evolution: the past, the present, and the future | Microbes | Scoop.it
Almost all land plants form symbiotic associations with mycorrhizal fungi. These below-ground fungi play a key role in terrestrial ecosystems as they regulate nutrient and carbon cycles, and influence soil structure and ecosystem multifunctionality. Up to 80% of plant N and P is provided by mycorrhizal fungi and many plant species depend on these symbionts for growth and survival. Estimates suggest that there are c. 50 000 fungal species that form mycorrhizal associations with c. 250 000 plant species. The development of high-throughput molecular tools has helped us to better understand the biology, evolution, and biodiversity of mycorrhizal associations. Nuclear genome assemblies and gene annotations of 33 mycorrhizal fungal species are now available providing fascinating opportunities to deepen our understanding of the mycorrhizal lifestyle, the metabolic capabilities of these plant symbionts, the molecular dialogue between symbionts, and evolutionary adaptations across a range of mycorrhizal associations. Large-scale molecular surveys have provided novel insights into the diversity, spatial and temporal dynamics of mycorrhizal fungal communities. At the ecological level, network theory makes it possible to analyze interactions between plant–fungal partners as complex underground multi-species networks. Our analysis suggests that nestedness, modularity and specificity of mycorrhizal networks vary and depend on mycorrhizal type. Mechanistic models explaining partner choice, resource exchange, and coevolution in mycorrhizal associations have been developed and are being tested. This review ends with major frontiers for further research.

Via Jean-Michel Ané
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Jean-Michel Ané's curator insight, February 2, 12:36 PM

Great review... a must-read.

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Temporal patterns of orchid mycorrhizal fungi in meadows and forests as revealed by 454 pyrosequencing - Oja - 2014 - New Phytologist - Wiley Online Library

Temporal patterns of orchid mycorrhizal fungi in meadows and forests as revealed by 454 pyrosequencing - Oja - 2014 - New Phytologist - Wiley Online Library | Microbes | Scoop.it
Orchid mycorrhizal (OrM) symbionts play a key role in the growth of orchids, but the temporal variation and habitat partitioning of these fungi in roots and soil remain unclear.Temporal changes in root and rhizosphere fungal communities of Cypripedium calceolus, Neottia ovata and Orchis militaris were studied in meadow and forest habitats over the vegetation period by using 454 pyrosequencing of the full internal transcribed spacer (ITS) region.The community of typical OrM symbionts differed by plant species and habitats. The root fungal community of N. ovata changed significantly in time, but this was not observed in C. calceolus and O. militaris. The rhizosphere community included a low proportion of OrM symbionts that exhibited a slight temporal turnover in meadow habitats but not in forests. Habitat differences in OrM and all fungal associates are largely attributable to the greater proportion of ectomycorrhizal fungi in forests.Temporal changes in OrM fungal communities in roots of certain species indicate selection of suitable fungal species by plants. It remains to be elucidated whether these shifts depend on functional differences inside roots, seasonality, climate or succession.
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Rescooped by David Biate from Plant Immunity And Microbial Effectors
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Phytohormones as integrators of environmental signals in the regulation of mycorrhizal symbioses

Phytohormones as integrators of environmental signals in the regulation of mycorrhizal symbioses | Microbes | Scoop.it
 
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SummaryFor survival, plants have to efficiently adjust their phenotype to environmental challenges, finely coordinating their responses to balance growth and defence.

Via IPM Lab
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Rescooped by David Biate from MycorWeb Plant-Microbe Interactions
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Arbuscular mycorrhizal dialogues: do you speak ‘plantish’ or ‘fungish’?

Arbuscular mycorrhizal dialogues: do you speak ‘plantish’ or ‘fungish’? | Microbes | Scoop.it
Plants rely on their associated microbiota for crucial physiological activities; realization of this interaction drives research to understand inter-domain communication. This opinion article focuses on the arbuscular mycorrhizal (AM) symbiosis, which involves the Glomeromycota, fungi that can form a symbiosis with most plants. Here we propose the hypothesis that the molecules involved in inter-kingdom symbiotic signaling, such as strigolactones, cutin monomers, and chitin-related molecules, also have key roles in development, originally unrelated to symbiosis. Thus, the symbiotic role of these molecules relies on the co-evolved capacity of the AM partners to perceive and interpret them as symbiotic signals.

Via Francis Martin
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Rescooped by David Biate from Plant Pathogenomics
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Nature Communications: The evolution and pathogenic mechanisms of the rice sheath blight pathogen (2013)

Nature Communications: The evolution and pathogenic mechanisms of the rice sheath blight pathogen (2013) | Microbes | Scoop.it
Rhizoctonia solani is a major fungal pathogen of rice (Oryza sativa L.) that causes great yield losses in all rice-growing regions of the world. Here we report the draft genome sequence of the rice sheath blight disease pathogen, R. solani AG1 IA, assembled using next-generation Illumina Genome Analyser sequencing technologies. The genome encodes a large and diverse set of secreted proteins, enzymes of primary and secondary metabolism, carbohydrate-active enzymes, and transporters, which probably reflect an exclusive necrotrophic lifestyle. We find few repetitive elements, a closer relationship to Agaricomycotina among Basidiomycetes, and expand protein domains and families. Among the 25 candidate pathogen effectors identified according to their functionality and evolution, we validate 3 that trigger crop defence responses; hence we reveal the exclusive expression patterns of the pathogenic determinants during host infection.
Via Kamoun Lab @ TSL
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Roots and microbes: Bringing a complex underground ecology into ...

Roots and microbes: Bringing a complex underground ecology into ... | Microbes | Scoop.it
The work establishes an experimental framework for examining how plants interact with a microbial community that can influence their growth and development, productivity, and impact on the environment.
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Earth 2050 - full length video

By the year 2050, the world's population will reach nine billion. The demand on the world's resources - energy, first and foremost - will be severe. But the road from now to then doesn't need be bleak.
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Rescooped by David Biate from Plant-Microbe Symbioses
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Microbial hotspots and hot moments in soil: Concept & review

Microbial hotspots and hot moments in soil: Concept & review | Microbes | Scoop.it
Soils are the most heterogeneous parts of the biosphere, with an extremely high differentiation of properties and processes within nano-to macroscales. The spatial and temporal heterogeneity of input of labile organics by plants creates microbial hotspots over short periods of time – the hot moments. We define microbial hotspots as small soil volumes with much faster process rates and much more intensive interactions compared to the average soil conditions. Such hotspots are found in the rhizosphere, detritusphere, biopores (including drilosphere) and on aggregate surfaces, but hotspots are frequently of mixed origin. Hot moments are short-term events or sequences of events inducing accelerated process rates as compared to the average rates. Thus, hotspots and hot moments are defined by dynamic characteristics, i.e. by process rates.

For this hotspot concept we extensively reviewed and examined the localization and size of hotspots, spatial distribution and visualization approaches, transport of labile C to and from hotspots, lifetime and process intensities, with a special focus on process rates and microbial activities. The fraction of active microorganisms in hotspots is 2–20 times higher than in the bulk soil, and their specific activities (i.e. respiration, microbial growth, mineralization potential, enzyme activities, RNA/DNA ratio) may also be much higher. The duration of hot moments in the rhizosphere is limited and is controlled by the length of the input of labile organics. It can last a few hours up to a few days. In the detritusphere, however, the duration of hot moments is regulated by the output – by decomposition rates of litter – and lasts for weeks and months. Hot moments induce succession in microbial communities and intense intra- and interspecific competition affecting C use efficiency, microbial growth and turnover. The faster turnover and lower C use efficiency in hotspots counterbalances the high C inputs, leading to the absence of strong increases in C stocks. Consequently, the intensification of fluxes is much stronger than the increase of pools. Maintenance of stoichiometric ratios by accelerated microbial growth in hotspots requires additional nutrients (e.g. N and P), causing their microbial mining from soil organic matter, i.e. priming effects. Consequently, priming effects are localized in microbial hotspots and are consequences of hot moments. We estimated the contribution of the hotspots to the whole soil profile and suggested that, irrespective of their volume, the hotspots are mainly responsible for the ecologically relevant processes in soil. By this review, we raised the importance of concepts and ecological theory of distribution and functioning of microorganisms in soil.

Via Jean-Michel Ané
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Jean-Michel Ané's curator insight, February 14, 1:30 PM

Very interesting ideas

Rescooped by David Biate from Plant-Microbe Symbioses
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A Genomic Encyclopedia of the Root Nodule Bacteria: assessing genetic diversity through a systematic biogeographic survey

Root nodule bacteria are free-living soil bacteria, belonging to diverse genera within the Alphaproteobacteria and Betaproteobacteria, that have the capacity to form nitrogen-fixing symbioses with legumes. The symbiosis is specific and is governed by signaling molecules produced from both host and bacteria. Sequencing of several model RNB genomes has provided valuable insights into the genetic basis of symbiosis. However, the small number of sequenced RNB genomes available does not currently reflect the phylogenetic diversity of RNB, or the variety of mechanisms that lead to symbiosis in different legume hosts. This prevents a broad understanding of symbiotic interactions and the factors that govern the biogeography of host-microbe symbioses.

Here, we outline a proposal to expand the number of sequenced RNB strains, which aims to capture this phylogenetic and biogeographic diversity. Through the Vavilov centers of diversity (Proposal ID: 231) and GEBA-RNB (Proposal ID: 882) projects we will sequence 107 RNB strains, isolated from diverse legume hosts in various geographic locations around the world. The nominated strains belong to nine of the 16 currently validly described RNB genera. They include 13 type strains, as well as elite inoculant strains of high commercial importance. These projects will strongly support systematic sequence-based studies of RNB and contribute to our understanding of the effects of biogeography on the evolution of different species of RNB, as well as the mechanisms that determine the specificity and effectiveness of nodulation and symbiotic nitrogen fixation by RNB with diverse legume hosts.

Via Jean-Michel Ané
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Rescooped by David Biate from Plant-Microbe Symbioses
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Rhizoxin Analogs Contribute to the Biocontrol Activity of a Newly Isolated Pseudomonas Strain

Two strains of Pseudomonas sp., Os17 and St29, were newly isolated from the rhizosphere of rice and potato, respectively, by screening for 2,4-diacetylphloroglucinol producers. These strains were found to be the same species and were the closest to but different from Pseudomonas protegens among the sequenced pseudomonads, based on 16S ribosomal RNA gene and whole-genome analyses. Strain Os17 was as effective a biocontrol agent as reported for P. protegens Cab57, whereas strain St29 was less effective. The whole-genome sequences of these strains were obtained: the genomes are organized into a single circular chromosome with 6,885,464 bp, 63.5% G+C content, and 6,195 coding sequences for strain Os17; and with 6,833,117 bp, 63.3% G+C content, and 6,217 coding sequences for strain St29. Comparative genome analysis of these strains revealed that the complete rhizoxin analog biosynthesis gene cluster (approximately 79 kb) found in the Os17 genome was absent from the St29 genome. In an rzxB mutant, which lacks the polyketide synthase essential for the production of rhizoxin analogs, the growth inhibition activity against fungal and oomycete pathogens and the plant protection efficacy were attenuated compared with those of wild-type Os17. These findings suggest that rhizoxin analogs are important biocontrol factors of this strain.

Via Jean-Michel Ané
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Rescooped by David Biate from Plant-Microbe Symbioses
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Transcriptome profiling of Bacillus subtilis OKB105 in response to rice seedlings

Transcriptome profiling of Bacillus subtilis OKB105 in response to rice seedlings | Microbes | Scoop.it
Background
Plant growth-promoting rhizobacteria (PGPR) are soil beneficial microorganisms that colonize plant roots for nutritional purposes and accordingly benefit plants by increasing plant growth or reducing disease. However, the mechanisms and pathways involved in the interactions between PGPR and plants remain unclear. In order to better understand these complex plant-PGPR interactions, changes in the transcriptome of the typical PGPR Bacillus subtilis in response to rice seedlings were analyzed.

Results
Microarray technology was used to study the global transcriptionl response of B. subtilis OKB105 to rice seedlings after an interaction period of 2 h. A total of 176 genes representing 3.8% of the B. subtilis strain OKB105 transcriptome showed significantly altered expression levels in response to rice seedlings. Among these, 52 were upregulated, the majority of which are involved in metabolism and transport of nutrients, and stress responses, including araA, ywkA, yfls, mtlA, ydgG et al. The 124 genes that were downregulated included cheV, fliL, spmA and tua, and these are involved in chemotaxis, motility, sporulation and teichuronic acid biosynthesis, respectively.

Conclusions
We present a transcriptome analysis of the bacteria Bacillus subtilis OKB105 in response to rice seedings. Many of the 176 differentially expressed genes are likely to be involved in the interaction between Gram-positive bacteria and plants.

Via Jean-Michel Ané
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Rescooped by David Biate from Plant-Microbe Symbioses
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Rapid quantification of rice root-associated bacteria by flow cytometry

Abstract
To understand the mechanism of plant–bacterium interaction, it is critical to enumerate epiphytic bacteria colonizing the roots of the host. We developed a new approach, based on flow cytometry, for enumerating these bacteria and used it with rice plants, 7 and 20 days after colonization with Herbaspirillum rubrisubalbicans and Azospirillum brasilense. The results were compared with those obtained with the traditional plate count method. Both methods gave similar numbers of H. rubrisubalbicans associated with rice roots (c. 109 CFU g−1). However, flow cytometry gave a number of viable cells of rice-associated A. brasilense that was approx. 10-fold greater than that obtained with the plate count method. These results suggest that the plate count method can underestimate epiphytic populations. Flow cytometry has the additional advantage that it is more precise and much faster than the plate count method.

Significance and Impact of the Study
Determination of precise number of root-associated bacteria is critical for plant–bacteria interaction studies. We developed a flow cytometry approach for counting bacteria and compared it with the plate count method. Our flow cytometry assay solves two major limitations of the plate count method, namely that requires long incubation times of up to 48 h and only determines culturable cells. This flow cytometry assay provides an efficient, precise and fast tool for enumerating epiphytic cells.

Via Stéphane Hacquard, Jean-Michel Ané
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Jean-Michel Ané's curator insight, February 11, 10:33 PM

Tired of doing plate counts?

Rescooped by David Biate from Plant-Microbe Symbioses
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Selection for cheating across disparate environments in the legume-rhizobium mutualism

The primary dilemma in evolutionarily stable mutualisms is that natural selection for cheating could overwhelm selection for cooperation. Cheating need not entail parasitism; selection favours cheating as a quantitative trait whenever less-cooperative partners are more fit than more-cooperative partners. Mutualisms might be stabilised by mechanisms that direct benefits to more-cooperative individuals, which counter selection for cheating; however, empirical evidence that natural selection favours cheating in mutualisms is sparse. We measured selection on cheating in single-partner pairings of wild legume and rhizobium lineages, which prevented legume choice. Across contrasting environments, selection consistently favoured cheating by rhizobia, but did not favour legumes that provided less benefit to rhizobium partners. This is the first simultaneous measurement of selection on cheating across both host and symbiont lineages from a natural population. We empirically confirm selection for cheating as a source of antagonistic coevolutionary pressure in mutualism and a biological dilemma for models of cooperation.

Via Jean-Michel Ané
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Mycorrhizal networks and coexistence in species-rich orchid communities - Jacquemyn - 2015 - New Phytologist - Wiley Online Library

Mycorrhizal networks and coexistence in species-rich orchid communities - Jacquemyn - 2015 - New Phytologist - Wiley Online Library | Microbes | Scoop.it
Multispecies assemblages often consist of a complex network of interactions. Describing the architecture of these networks is a first step in understanding the stability and persistence of these species-rich communities. Whereas a large body of research has been devoted to the description of above-ground interactions, much less attention has been paid to below-ground interactions, probably because of difficulties to adequately assess the nature and diversity of interactions occurring below the ground.In this study, we used 454 amplicon pyrosequencing to investigate the architecture of the network between mycorrhizal fungi and 20 orchid species co-occurring in a species-rich Mediterranean grasslands.We found 100 different fungal operational taxonomic units (OTUs) known to be mycorrhizal in orchids, most of which were members related to the genera Ceratobasidium and Tulasnella. The network of interactions was significantly compartmentalized (M = 0.589, P = 0.001), but not significantly nested (N = 0.74, NODF = 10.58; P > 0.05). Relative nestedness was negative (N* = −0.014), also suggesting the existence of isolated groups of interacting species.Compartmentalization is a typical feature of ecological systems showing high interaction intimacy, and may reflect strong specialization between orchids and fungi resulting from physiological, physical or spatial constraints.
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Phytohormones as integrators of environmental signals in the regulation of mycorrhizal symbioses

Phytohormones as integrators of environmental signals in the regulation of mycorrhizal symbioses | Microbes | Scoop.it
 
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SummaryFor survival, plants have to efficiently adjust their phenotype to environmental challenges, finely coordinating their responses to balance growth and defence.

Via IPM Lab
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Rescooped by David Biate from Plant-Microbe Symbioses
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21st century agriculture: integration of plant microbiomes for improved crop production and food security

21st century agriculture: integration of plant microbiomes for improved crop production and food security | Microbes | Scoop.it

Via Jean-Michel Ané
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Rescooped by David Biate from Rhizobium Research
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Engineering the plant rhizosphere

Engineering the plant rhizosphere | Microbes | Scoop.it
Plant natural products are low molecular weight compounds playing important roles in plant survival under biotic and abiotic stresses. In the rhizosphere, several groups of plant natural products function as semiochemicals that mediate the interactions of plants with other plants, animals and microorganisms. The knowledge on the biosynthesis and transport of these signaling molecules is increasing fast. This enables us to consider to optimize plant performance by changing the production of these signaling molecules or their exudation into the rhizosphere. Here we discuss recent advances in the understanding and metabolic engineering of these rhizosphere semiochemicals.

Via Jean-Michel Ané, IvanOresnik
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Rescooped by David Biate from Rhizobium Research
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Microevolution of symbiotic Bradyrhizobium populations associated with soybeans in east North America

Abstract

Microevolution and origins of Bradyrhizobium populations associated with soybeans at two field sites (A and B, 280 km apart in Canada) with contrasting histories of inoculation was investigated using probabilistic analyses of six core (housekeeping) gene sequences. These analyses supported division of 220 isolates in five lineages corresponding either to B. japonicum groups 1 and 1a or to one of three novel lineages within the genus Bradyrhizobium. None of the isolates from site A and about 20% from site B (the only site with a recent inoculation history) were attributed to inoculation sources. The data suggest that most isolates were of indigenous origin based on sequence analysis of 148 isolates of soybean-nodulating bacteria from native legumes (Amphicarpaea bracteata and Desmodium canadense). Isolates from D. canadense clustered with B. japonicum group 1, whereas those from A. bracteata were placed in two novel lineages encountered at soybean field sites. One of these novel lineages predominated at soybean sites and exhibited a significant clonal expansion likely reflecting selection by the plant host. Homologous recombination events detected in the 35 sequence types from soybean sites had an effect on genetic diversification that was approximately equal to mutation. Interlineage transfer of core genes was infrequent and mostly attributable to gyrB that had a history of frequent recombination. Symbiotic gene sequences (nodC and nifH) of isolates from soybean sites and native legumes clustered in two lineages corresponding to B. japonicum and B. elkani with the inheritance of these genes appearing predominantly by vertical transmission. The data suggest that soybean-nodulating bacteria associated with native legumes represent a novel source of ecologically adapted bacteria for soybean inoculation.

 

Tang J, Bromfield ES, Rodrigue N, Cloutier S, Tambong JT. (2012).  Ecol Evol. Dec;2(12):2943-61. doi: 10.1002/ece3.404. Epub 2012 Oct 22.


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IvanOresnik's curator insight, January 10, 2013 1:53 PM

The authors present data that suggests native Bradyrhizobia are selected by the planted soybean crop rather than having a horizontal gene transfer event from the inoculant stranins to the native strains.  Regardless, there are implications for finding inoculant strains that may be better sutied to some areas.

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DOE JGI Science Highlights: Prototypical genomic study of Plant ...

DOE JGI Science Highlights: Prototypical genomic study of Plant ... | Microbes | Scoop.it
DOE JGI Science Highlights: Prototypical genomic study of Plant-Microbe Interaction. Instead of using dangerous and toxic pesticides or expensive fertilizers, farmers may one day use microbes to fully manage diseases in soil ...
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