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Approche de la diversité inter- et intraspécifique des champignons mycorhiziens à arbuscule

Abstract : Arbuscular mycorrhizal fungi are an important group of microorganisms in the rhizosphere because of their ubiquity in terrestrial ecosystems and the symbiotic association that they form with more than 80 % of plant species. Mycorrhizas improve plant mineral nutrition as weIl as resistance to environmental stress. However, little is known on the diversity of these fungi in soil, either at an inter or intraspecific level, and on the relationship between diversity and function. The objectives of the thesis were (1) to set up molecular tools to study the diversity of AM fungi and (2) to caracterise the populations of AM fungi in 3 soils amended with different levels of sewage sludge using these tools. First, species richness and spore abondance were estimated. The same 6 species were found in the three soils. Spore abundance was lower in the plot which received the highest sludge amendment, which could be related to the modification of soil parameters due to the amendments (heavy metals, pH, ...). Two molecular techniques (PCR fingerprinting using a microsatellite primer, analysis of the small sub-unit ribosomal DNA using PCR) were developped, validated and applied with isolates of Glomus mosseae from collection cultures. These techniques were used to study the populations of the 2 most abundant species found in the studied soils (Glomus geosporum-like and Glomus claroideum ). A high intraspecific variability was observed for both species and for both of them the populations of the three soils were genetically different. A high structuration of the populations was observed, although the samples were only distant of a few meters. The mechanisms involved in the high diversity remains to be explained, but data analysis suggests a clonal reproduction and also recombination events. Finally, the host-plant as weIl as the soil influence the intraspecific diversity of G. claroideum.
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Submitted on : Thursday, March 29, 2018 - 11:01:09 AM
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Philippe Vandenkoornhuyse. Approche de la diversité inter- et intraspécifique des champignons mycorhiziens à arbuscule. Microbiologie et Parasitologie. Université Henri Poincaré - Nancy 1, 1998. Français. ⟨NNT : 1998NAN10316⟩. ⟨tel-01747480⟩



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