Medicago species affect the community composition of arbuscular mycorrhizal fungi associated with roots

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Pivato, Barbara | Mazurier, Sylvie, S. | Lemanceau, Philippe, P. | Siblot, Séverine, S. | Berta, Graziella | Mougel, Christophe | van Tuinen, Diederik, D.

Edité par CCSD -

National audience. The symbiosis between plants and arbuscular mycorrhizal fungi (AMF) is ancient and involves 80% of terrestrial plant families. The symbiotic association between AMF and plants was described to be non specific. However, AMF were reported to influence plant community diversity and productivity. On the other way, the effect of plant genotypes belonging to closely related species on AMF diversity has not been explored so far. The aim of this work was to assess the impact of four different Medicago species, M. laciniata, M. murex, M. polymorpha and M. truncatula cv. Jemalong J5, on the composition of AM fungal community, when cultivated in a silty-thin clay soil (Mas d’Imbert, France). A nested PCR targeting partial sequence of the variable domains D1 and D2 of the large ribosomal subunit (LSU rDNA) genes was performed on DNA extracted from bulk soil and root tissues. PCR products were used to construct LSU rDNA libraries. Two hundred forty-six Glomeromycetes LSU rDNA sequences from the four plant species and bulk soil were analysed. The high bootstrap values of the phylogenetic tree obtained allowed the delineation of 12 Operational Taxonomic Units (OTUs), all belonging to Glomus. Specific primers targeting Glomeromycetes and major OTUs were applied to quantify their abundance by qPCR. Glomeromycetes and targeted OTUs were significantly more abundant in the root tissues than in the bulk soil, and the frequency of Glomeromycetes and of three OTUs differed significantly in the root tissues of the different plant species. These differences indicate that, despite the absence of strict host specificity in mycorrhizal symbiosis, there was a preferential association between some AM fungal and plant genotypes. Pivato B., Mazurier S., Lemanceau P., Siblot S., Berta G., Mougel C., van Tuinen D. Medicago species affect the community composition of arbuscular mycorrhizal fungi associated with roots. New Phytol. In press.

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