Biologie des communautés dans la rhizosphère : analyse des interactions plantes - champignons mycorhizogènes à arbuscules - bactéries

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Strategies for analyzing interactions between arbuscular mycorrhiza and bacteria

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Effect of Arbuscular Mycorrhiza establishment on the genetic structure and functionality of bacterial communities in the rhizosphere of Medicago truncatula

Bacterial communities associated with (i) M. Truncatula J5 (Myc+/Nod+) and TRV48 (Myc+/Nod-), and with (ii) M. Truncatula TRV25 (Myc-/Nod-) were compared. The genetic structure of communities was characterized with an A-RISA DNA fingerprint. The genetic structures of communities associated with mycorrhizal and non-mycorrhizal roots were significantly different. Bacteria belonging to the Oxalobacteraceae and Comamonadaceae families were preferentially associated with mycorrhizal roots. The genetic diversity of cultured bacteria belonging to these groups was analysed by BOX-PCR. The diversity of isolates from mycorrhizal and non-mycorrhizal roots was significantly different. The functionality…

Dynamic of the genetic structure of bacterial and fungal communities at different developmental stages of Medicago truncatula Gaertn. cv. Jemalong line J5

International audience; The genetic structure of bacterial and fungal communities was characterized in the rhizosphere of Medicago truncatula Gaertn. cv. Jemalong line J5 at five developmental stages (three vegetative and two reproductive stages), and in three compartments (bulk soil, rhizosphere soil and root tissues). The genetic structure of microbial communities was determined by cultivation-independent methods using directly extracted DNA that was characterized by automated ribosomal intergenic spacer analysis (ARISA). Principal component analyses (PCA) indicate that, for all developmental stages, the genetic structure of microbial communities differed significantly by compartment, wit…

Microdiversity of Burkholderiales associated with mycorrhizal and nonmycorrhizal roots of Medicago truncatula

The genetic diversity of bacterial communities associated with mycorrhizal and nonmycorrhizal roots of Medicago truncatula was characterized by two approaches. Firstly, phylogenetic analysis was performed on 164 partial 16S rRNA gene-intergenic spacer (IGS) sequences from operational taxonomic units previously shown to be preferentially associated with mycorrhizal roots. These sequences were distributed into three branches corresponding to Comamonadaceae, Oxalobacteraceae and Rubrivivax subgroups. Most sequences were obtained from mycorrhizal roots, indicating the preferential association of the corresponding families with mycorrhizal roots. A second phylogenetic analysis was performed on t…

Studying the arbuscular mycorrhizal symbiosis from axenic system to soilborne interactions by proteomics: which challenges to face?

Identification of bacterial groups preferentially associated with mycorrhizal roots of Medicago truncatula

ABSTRACT The genetic structures of bacterial communities associated with Medicago truncatula Gaertn. cv. Jemalong line J5 (Myc + Nod + ) and its symbiosis-defective mutants TRV48 (Myc + Nod − ) and TRV25 (Myc − Nod − ) were compared. Plants were cultivated in a fertile soil (Châteaurenard, France) and in soil from the Mediterranean basin showing a low fertility (Mas d'Imbert, France). Plant growth, root architecture, and the efficiency of root symbiosis of the three plant genotypes were characterized in the two soils. Structures of the bacterial communities were assessed by automated-ribosomal intergenic spacer analysis (A-RISA) fingerprinting from DNA extracted from the rhizosphere soil an…

Toward an integrated approach for studying plant-microbe interactions in the rhizosphere: from genomic to proteomic

International audience

Microbial ecology of the rhizosphere

Part II. Selected MethodsPlant-microbe Chapitre 9 : Interactions and Soil Quality; International audience

Proteomes of arbuscular mycorrhizal symbiosis : past and present achievements

Effect of arbuscular mycorrhiza establishment on the genetic structure and diversity of bacteria in the rhizosphere of Medicago truncatula

National audience; The rhizosphere is the volume of soil which is influenced by plant root activity. Plant roots release 20% of the photosynthates into the rhizosphere. This process sustains the development of an active free living microflora in the rhizosphere compared to the bulk soil. Plants establish also symbiotic associations with soil microorganisms. Arbuscular mycorrhizas (AM) are mutualistic symbioses between soil fungi and plant roots. AM contribute to plant adaptation to low fertility environments. AM are established by 80% of terrestrial plant families including major crop plants. AM are also ancient symbiosis (400 million years). AM are known to be non-specific associations. Ho…

Interactions durables entre plantes et microorganismes dans les sols

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