ARS | Publication request: Genetic diversity and population structure of Aspergillus flavus in the southern USA

Submitted to: Mycological Society of America
Publication Type: Abstract Only
Publication Acceptance Date: June 1, 2011
Publication Date: June 1, 2011
Citation: Grubisha, L.C., Cotty, P.J. 2011. Genetic diversity and population structure of Aspergillus flavus in the southern USA[abstract]. Mycological Society of America. 62(3):21.

Technical Abstract: Aspergillus flavus is a fungal pathogen of animals and wild and domesticated plants with a global distribution. During infection by A. flavus, crops are frequently contaminated with highly carcinogenic aflatoxins. A. flavus populations are composed of numerous vegetative compatibility groups (VCGs), however, not all VCGs produce aflatoxin. In a series of studies, several types of genetic markers (24 microsatellite loci, mating-type loci, SNPs) were used to assess genetic diversity, population structure and reproductive mode in A. flavus populations in the southern USA, including a study of YV36, the VCG to which the biocontrol fungus AF36 belongs. In all studies VCGs formed lineages of genetically similar individuals, with few exceptions. The results of analyses of 21 microsatellite loci from across the genome support the hypothesis that VCG YV36 is a clonal lineage with one dominant haplotype distributed both spatially and temporally in fields not treated with AF36. Furthermore, all isolates of YV36, including isolates from fields previously treated with AF36, had MAT1-2 and the SNP in the aflC/pksA gene resulting in a defective polyketide synthase and responsible for the lack of aflatoxin accumulation in YV36. Results from these studies did not support the hypothesis of random mating among VCGs of MAT1-1 and MAT1-2 in populations in the southern USA. These results have important implications for development of biological control programs using indigenous, nonaflatoxin-producing VCGs.