Mycobiota and Potential Mycotoxin Contamination of Soybean RR in Different Production Areas in Argentina

Abstract

A total of 348 freshly harvested soybean samples from a multi-environment trial, conducted in experimental fields belonging to INTA (Instituto Nacional de Tecnología Agropecuaria) in 12 localities, were analyzed for mycotoxin natural occurrence and for determining the associated endogenous mycoflora. Aflatoxins (AFs) and zearalenone (ZEN) were analyzed by HPLC and deoxynivalenol (DON) by CG.Samples from Reconquista, Tres Pozos, Rafaela and Manfredi were the most infested by fungi and those from Barrow and Balcarce the less contaminated. A total of 13,316 fungal isolates were identified from the seeds of 32 Roundup® Ready (transgenic) soybean cultivars. All fungi isolated were mitosporic fungi and ascomycetes. The most common fungi identified included species that belong to Alternaria, Fusarium, Sclerotinia, Phomopsis, Rhizoctonia and Cladosporium genera. The isolation frequencies and relative densities of species were calculated. Alternaria alternata, Fusarium equiseti, Sclerotinia sclerotiorum, Phomopsis spp., Fusarium semitectum, Cladosporium cladosporioides and Rhizoctonia solani were the predominant fungal species identified as endogenous mycoflora. No soybean samples were naturally contaminated with AFs, DON or ZEN. This is the first report on contaminant mycoflora and mycotoxin natural occurrence in transgenic soybean seeds from an extensive production area in Argentina.