Maize production is important to both US agriculture and economy. Mycotoxins, toxins produced by various fungal sources, are a significant economic and safety threat to US crops. In the US, aflatoxin is the most problematic of the mycotoxins, where contamination of food/feed results in an estimated $270M agricultural loss every year. Elimination of aflatoxin is a critical economic and health issue in the US. This project will develop previous work from the PI's laboratory on the very successful use of host-induced gene silencing (HIGS) in maize kernels engineered to silence a major biosynthetic aflatoxin gene (aflC) in contaminating aflatoxin-producing Aspergillus. This project will both assess the real-world effectiveness of the pre-harvest aflatoxin-silencing HIGS transgenic maize and the feasibility of adding a post-harvest aflatoxin elimination strategy in dry kernels. The research objectives of this project are: (1) determine the naturally-occurring sequence variation in the aflatoxin-biosynthetic pathway gene polyketide synthase (aflC) in Aspergillus strains; (2) investigate the effectiveness of the already in-hand HIGS maize at suppressing toxin production when infected with naturally-occurring Aspergillus strains varying in the targeted aflC sequence; and(3) investigate the extent of sequence homology necessary for effective HIGS suppression by exogenous application of dsRNA molecules with varying sequence homologies. This proposal addresses the Improving Food Safety Priority Code A1331 priority area to develop and validate novel strategies for control of persistent foodborne pathogens or other contaminants.