Location: Pest Management and Biocontrol Research2017 Annual Report
1. Expansion of Environmental Protection Agency (EPA) registered biopesticides for aflatoxin management. Biopesticides based on atoxigenic strains of Aspergillus flavus have become the most widely used intervention for preventing aflatoxin contamination. However, these biopesticides must be approved by and registered with regulatory authorities and each target crop and each atoxigenic genotype require additional regulatory action. Thousands of atoxigenic genotypes of A. flavus exist with broad adaptation but regulatory approval for use in commercial products has only been granted for a few genotypes. The ARS aflatoxin laboratory in Tucson, Arizona, addressed this through direct interactions with regulatory authorities, field and laboratory experimentation, and collaborations with the Arizona Cotton Research and Protection Council, the University of California, the International Institute of Tropical Agriculture, commodity groups, and several national governments. The result is new and expanded registrations of biopesticides directed at preventing aflatoxin contamination including approval for new target crops (figs and almonds), additional A. flavus genotypes, and less restrictive handling requirements. Full registrations in the U.S., Senegal, and Burkina Faso were added to existing registrations in the United States, Kenya, and Nigeria.
2. Iron utilization gene cluster variation within Aspergillus flavus provides new molecular tools for atoxigenic genotype selection. Certain genotypes of Aspergillus flavus, produce aflatoxins that contaminate food crops, including maize, peanuts, and tree nuts. Aspergillus flavus genotypes that do not produce toxin are widely used as biological control agents to reduce aflatoxin contamination of food and feed. Filamentous fungi like A. flavus have diverse mechanisms to uptake and use iron. ARS researchers in Tucson, Arizona, have identified and characterized a cluster of genes involved in iron uptake and utilization. Variation among A. flavus genotypes in iron utilization genes provides greater understanding of iron utilization process in the aflatoxin producing fungi. The genes identified in this study can potentially be used as genetic markers for use in profiling atoxigenic genotypes for biological control product development.
Adhikari, B.N., Bandhyopadhyay, R., Cotty, P.J. 2016. Degeneration of aflatoxin gene cluster in Aspergillus flavus from Africa and North America. Applied Microbiology and Biotechnology Express (AMB Express). 6:62. doi: 10.1186/s13568-016-0228-6.
Thakare, D., Zhang, J., Wing, R.A., Cotty, P.J., Schmidt, M.A. 2017. Aflatoxin-free transgenic maize using host-induced gene silencing. Science Advances. 3(3):e1602382.
Singh, P., Cotty, P.J. 2017. Aflatoxin contamination of dried red chilies: Contrasts between the United States and Nigeria, two markets differing in regulation enforcement. Food Control. 80:374-379.
Bandyopadhyay, R., Ortega-Beltran, A., Akande, A., Mutegi, C., Atechnkeng, J., Kaptoge, L., Senghor, A.L., Adhikari, B.N., Cotty, P.J. 2016. Biological control of aflatoxins in Africa: current status and potential challenges in the face of climate change. World Mycotoxin Journal. 9(5):771-789.