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<p>Host-induced gene silencing (HIGS) is promising new technology in which the pathogen is directed by the host plant to down-regulate the expression of its own genes. HIGS technology does not require that the host plant express a foreign protein so food and feed produced from resistant lines of transgenic maize should be more acceptable to regulatory agencies and consumers. Silencing constructs expressed in plants can knock-down the expression of fungal genes required for successful invasion and toxin production. The goal of the proposed research is to control preharvest aflatoxin contamination in maize through identification of Aspergillus flavus genes involved in fungal growth, development and toxin production to be targeted for silencing by an ribonucleic acid interference (RNAi)-mediated mechanism in transgenic host plants.</p>
<p>Utilizing information obtained from Aspergillus (A.) flavus proteomic and genomic studies we will identify candidate fungal genes that are required for successful invasion and aflatoxin production during the A. flavus-maize interaction. Ribonucleic acid interference (RNAi) vectors targeting these candidate genes will be constructed and initially assayed in A. flavus for efficacy in knockdown of target gene expression. Efficacious constructs will then be optimized for expression in maize and binary RNAi constructs subsequently introduced into maize. Seed from transgenic lines will be assayed by polymerase chain reaction based techniques for presence of the transgene as well as expression of the hairpin ribonucleic acid (RNA). Seed from positive lines will be used in kernel screening assays (KSAs) to determine if expression of target fungal gene(s) is significantly downregulated leading to decreased fungal growth and aflatoxin production. Maize lines demonstrating significant resistance to A. flavus growth and toxin production will have their seed bulked and used further as breeding material.</p>