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Poster: Epidemiology: Population Biology Genetics


Diversity of Aspergillus flavus on important agricultural crops produced in Bangladesh
M. ISLAM (1), P. Cotty (2) (1) USDA ARS, U.S.A.; (2) USDA-ARS, School of Plant Sciences, the University of Arizona, U.S.A.

The hot, humid climate of Bangladesh is ideal for aflatoxin producing fungi. As a result, rice, maize, peanut, wheat and other crops grown in Bangladesh may become infected by these fungi and contaminated with dangerous concentrations of aflatoxins. Aflatoxins are toxic fungal metabolites produced by A. flavus, A. parasiticus, and closely related species. Aflatoxins cause increased risk of liver cancer, stunting, immune suppression, and in cases of acute exposure, liver necrosis and death. However, frequencies of aflatoxins and diversity of aflatoxin-producing fungi in crops of Bangladesh are poorly understood. To assess the magnitude of aflatoxin contamination and diversity of A. flavus in crops produced in Bangladesh, maize, rice, wheat and peanut samples were collected from 12 districts covering the major agro-ecological regions of Bangladesh. Aflatoxins were quantified in crop samples using immunochromatographic assays. Variable levels of aflatoxins were detected across the samples with a maximum concentration of 122.8 µg/kg total aflatoxins. Fungi associated with the maize and belonging to the L-strain morphotype were genotyped using 16 SSR markers. Genetic diversity of the L morphotype was high with 5 to 24 alleles per SSR locus, and 46 haplotypes among 50 isolates. Atoxigenic strains of A. flavus of potential value in aflatoxin prevention and native to Bangladesh were characterized.