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<OL> <LI> Control aflatoxin contamination of cottonseed through incorp. of foreign antifungal genes into cotton by genetic engineering. <LI> Enhance resistance to A. flavus invasion in corn and cotton through induction of native host plant defense chemicals. <LI> Determine plant stress effects on abilities of cotton and corn to mount defenses against A. flavus. <LI> Identify resistant corn inbreds for resistance to aflatoxin contamination and associated biochemical resistance markers for use in marker assisted breeding.
Cotton meristematic tissue will be transformed with antifungal genes via the biolistic method and regenerated into fully developed coton plants. To assess the effectiveness of candidate genes to inhibit growth of A. flavus in cotton, genes will be placed under constitutive control using the CaMV 35S promoter. Genes effective against A. flavus will be placed under more selective control (e.g., seed specific expression) using specific promoter elements. Cottonseed and corn kernels will be treated with elicitors derived from fungal cell walls and/or the lipoxygenase pathway in cotton to test for induction of native plant resistances to A. flavus. Anatomical and biochemical changes will be measured in cotton and corn which are related to water and/or nutrient stress and to defensive capabilities against A. flavus invasion. A reporter gene-containing tester strain of A. flavus will be used to detect and localize antifungal activities/traits in individual corn kernels of inbred lines used in breeding commercial corn hybrids resistant to aflatoxin contamination.