Submitted to: Mycotoxin Research
Publication Type: Review Article
Publication Acceptance Date: January 10, 2006
Publication Date: March 1, 2006
Citation: Rajasekaran, K., Cary, J.W., Cleveland, T.E. 2006. Prevention of preharvest aflatoxin contamination through genetic engineering of crops. Mycotoxin Research. 22(2):118-124. Technical Abstract: Aspergillus flavus and A. parasiticus, that produce aflatoxin in several crop species including cotton, peanuts, tree nuts and corn, are not true plant pathogens but opportunistic, saprophytic fungi. Defense mechanisms elicited in affected crop plants are not specific to these saprophytic fungi. At present, disease management in crop fields is practiced solely through adaptation of suitable cultural practices such as rotation, use of quality seed and fungicides and altering the time of planting. In addition to post-harvest procedures through use of chemicals for aflatoxin prevention, several other viable means to prevent the contamination process in crops before harvest are being undertaken in several laboratories around the world. These technologies include use of resistant germplasm to breed for resistant varieties, biological control through the use of atoxigenic strains to compete and replace toxigenic strains in the field and enhancement of resistance in crops through genetic engineering. The later strategy is especially pertinent to cottonseed, which does not possess practical levels of natural resistance to aflatoxin-producing fungi in its germplasm base. Conventional breeding for disease-resistant crops, especially perennial crops, is very time consuming and does not lend itself ready to combat the evolution of new virulent fungal races. The steady unraveling of complex interactions between fungal pathogens such as Aspergilli and host plants has already paved the way for production of transgenic disease resistant crop plants. Transgenic approaches are being undertaken in several industry and academic laboratories to prevent invasion by Aspergillus fungi or to prevent biosynthesis of aflatoxin. We summarize here the recent trends in reducing aflatoxin contamination in cultivated crop species by biotechnology.