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Resistance to Aspergillus flavus in Corn Kernels Is Associated with a 14-kDa Protein

First and sixth authors: Department of Plant Pathology and Crop Physiology, Louisiana State University Agricultural Center, Baton Rouge 70803; second, third, and fifth authors: Southern Regional Research Center, USDA-ARS, New Orleans 70179; and fourth author: Plant Resistance/Germplasm Enhancement Research Unit, USDA-ARS, Tifton, GA 31793

Corn genotypes resistant or susceptible to Aspergillus flavus were extracted for protein analysis using a pH 2.8 buffer. The profile of protein extracts revealed that a 14-kDa protein is present in relatively high concentration in kernels of seven resistant corn genotypes, but is absent or present only in low concentration in kernels of six susceptible ones. The N-terminal sequence of this 14-kDa protein showed 100% homology to a corn trypsin inhibitor. The 14-kDa protein purified from resistant varieties also demonstrated in vitro inhibition of both trypsin activity and the growth of A. flavus. This is the first demonstration of antifungal activity of a corn 14-kDa trypsin inhibitor protein. The expression of this protein among tested genotypes may be related to their difference in resistance to A. flavus infection and subsequent aflatoxin contamination.

Additional keywords: antifungal protein .