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<OL> <LI>Identify constitutive protein differences in maize kernels between resistant and susceptible genotypes of five pairs of near isogenic lines using proteomics. <LI>Identify inducible protein differences in near isogenic maize lines upon Aspergillus flavus infection. <LI> Characterize these resistance-associated proteins (RAPs) to assist in understanding the host-parasite interactions between maize and A. flavus. <LI>Verify the importance of key RAPs in the expression of host disease resistance through RNAi gene silencing. The long-term objective of this proposed study is to enhance aflatoxin resistance in maize through either genetic engineering or marker-assisted breeding.
Non-Technical Summary: Aflatoxins, the toxic and highly carcinogenic secondary metabolites of A. flavus and A. parasiticus, are produced during infection of susceptible crops, such as maize, especially under hot and dry weather conditions. Aflatoxin contamination in food and feed not only causes millions of dollars in losses to U. S. farmers, but also poses serious health hazards to humans and domestic animals. Severe aflatoxin outbreaks occurred in Louisiana, other Southern states, and the Midwest Corn Belt in the past when there was a prolonged drought, such as the ones occurred in 1987 and 1998. The purpose of the present proposal is to enhance maize resistance to A. flavus infection/aflatoxin production through understanding of host-fungus interactions. Understanding these interactions and the host resistance mechanisms may enable us to develop commercial varieties that are resistant to A. flavus infection and aflatoxin contamination, which will not only reduce the economic losses to farmers, but also ensure food and feed safety. <P> Approach: 1. Extract, separate maize kernel embryo and endosperm proteins using proteomics, and compare for protein differences between between near isogenic maize lines with or without fungal infection. 2. Examine the biological functions of these proteins through gene cloning, enzyme or antifungal activity assays; 3. Using RNAi gene silencing to verify the importance of identified proteins in maize aflatoxin disease resistance.