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

Pivato, B., Mazurier, S., Lemanceau, P., Siblot, S., Berta, G., Mougel, C., van Tuinen, D.
New phytologist 2007 v.176 no.1 pp. 197-210
Glomus, Medicago murex, Medicago polymorpha, Medicago truncatula, clay soils, community structure, genetic variation, genotype, host specificity, mycorrhizal fungi, nucleotide sequences, phylogeny, protein subunits, quantitative polymerase chain reaction, ribosomal DNA, ribosomal proteins, roots, species diversity, vesicular arbuscular mycorrhizae, France
Sequencing of the 5' end of the large ribosomal subunit (LSU rDNA) and quantitative polymerase chain reaction (qPCR) were combined to assess the impact of four annual Medicago species (Medicago laciniata, Medicago murex, Medicago polymorpha and Medicago truncatula) on the genetic diversity of arbuscular mycorrhizal (AM) fungi, and on the relative abundance of representative AM fungal genotypes, in a silty-thin clay soil (Mas d'Imbert, France). Two hundred and forty-six Glomeromycete LSU rDNA sequences from the four plant species and the 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 frequencies of three of them 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.