|Kim, Jong Heon|
Submitted to: Mycotoxin Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 14, 2005
Publication Date: August 15, 2006
Citation: Kim, J.H., Campbell, B.C., Molyneux, R.J., Mahoney, N.E., Chan, K.L, Yu, J., Wilkinson, J.R., Cary, J., Bhatnagar, D., Cleveland, T.E. 2006. Gene targets for fungal and mycotoxin control. Mycotoxin Research. 22(1):3-8. Interpretive Summary: We found that safe natural compounds called antioxidants can completely inhibit biosynthesis of aflatoxin. Aflatoxin is a chemical made by certain fungi that can infect our food supply. This compound is the most carcinogenic natural compound known. Contamination of agricultural products by this compound results in billions of dollars of loss each year. After we discovered that antioxidants prevent aflatoxin biosynthesis, we discovered the inverse. That is, oxidative stress promotes aflatoxin biosynthesis. These discoveries provide significant information on how to prevent aflatoxin contamination of our food supply.
Technical Abstract: Gallic acid, from hydrolysable tannins in the pellicle of walnut kernels, dramatically inhibit biosynthesis of aflatoxin by Aspergillus flavus. Additional research using other antioxidant phenolics showed similar antiaflatoxigenic activity. Treatment of A. flavus with butyl peroxide resulted in an almost doubling of aflatoxin biosynthesis compared to untreated cohorts. Thus, antioxidative response systems are potential molecular targets for control of A. flavus. For example, the S. cerevisiae sod2 delta mutant was highly sensitive to treatment by certain phenolics and strobilurins/antimycin A, fungicides which inhibit complex III of the mitochondrial respiratory chain. Verification of stressing this system in the target fungus, A. flavus, was shown through complementation analysis, wherein the mitochondrial superoxide dismutase (Mn-SOD) gene (sodA) of A. flavus in the ortholog mutant, sod2 delta, of S. cerevisiae, relieved phenolic induced stress. Identifying the antioxidative response systems in other pathogens could improve methods for fungal control.