HIGH THROUGHPUT SEQUENCING ANALYSISOF ARBUSCULAR MYCORRHIZAL FUNGI DIVERSITY IN SOILS UNDER DIFFERENT AGRICULTURAL PRACTICES

ELSA BRÜCHER; ANDREA G. ALBARRACÍN ORIO; CRISTINA PLAZAS; GUSTAVO GUERRA; DANIEL A. DUCASSE

Mar del Plata

Congreso; VII Congreso Argentino de Microbiología General; 2012

Sociedad Argentina de Microbiología General

The symbiotic association between mycorrhizal fungi and the roots of plants is widespread in nature. There are several different types of fungi that form these associations, but for agriculture, the arbuscular mycorrhizal fungi (AMF) of the Phylum Glomeromycota are most important. AMF form a symbiotic association with more than 80 % of land plant families. AMF benefit their host principally by increasing uptake of relatively immobile phosphate ions, due to the ability of the fungal ERM to grow beyond the phosphate depletion zone that quickly develops around the root. In return, the fungus receives organic carbon (C) from the host plant. It is still little known how different agricultural management impact on arbuscular mycorrhizal fungi. The objective of this work is to detect changes in the arbuscular mycorrhizal fungi diversity in soils under different agricultural practices. For this reason, we performed pyrosequencing of a DNA fragment coding for the rRNA large subunit region (LSU) of Glomeromycota from 3 different fields under 3 types of soil management (good agricultural practices, GAP; bad agricultural practices, BAP; non altered soils or natural environments, NE) in Viale, Entre Ríos province, Argentine. Twelve soil samples were taken from 3 sites uniformly distributed along a line transect in each field (4 samples per site). Total soil microbial DNA was extracted and submitted to nested PCR reactions. Pyrosequencing of D2 LSU region was performed on a Genome Sequencer FLX System (Roche Applied Science). We achieved 31078 high quality pyrosequencing reads that were uploaded into the open-source QIIME project. The analysis of LSU rDNA regions allowed us to assign unequivocally 76.7% of all sequences to the Glomeromycetes class, 75.7% of which were included in the Glomeraceae family (Order Glomerales). The taxonomic distribution of the sequences obtained showed that only 0.4% of sequences were assigned to the Basiomycota phylum. We found 813 OTUs at a similarity level of 97%, most of them related to the Glomus genus. The proportion of AMF taxa was particularly elevated in GAP fields but richness estimators were unexpectedly lower than BAP and NE soil samples, with equitability indices high and similar to all the other samples analyzed. Principal component analysis of membership differences exposed a clear separation of GAP samples and a clustering of BAP and NE treatments, revealing dissimilarity in AMF occurrence between the agricultural managements. In conclusion, the pyrosequencing analysis of LSU region allowed us to evaluate AMF diversity in soils. In addition, these findings showed that AMF richness and diversity could be affected by good agriculture practices favoring the establishment of particular mycorrhizal communities.