Prevention of preharvest aflatoxin contamination through genetic engineering of crops.

Current practices on prevention of aflatoxin contamination of crop species include time consuming, expensive agronomic practices. Of all the methods available to-date, conventional breeding and/or genetic engineering to develop host plant-based resistance to aflatoxin-producing fungi appear to be valuable for several reasons. However, breeding for disease-resistant crops is very time consuming, especially in tree crops, and does not lend itself ready to combat the evolution of new virulent fungal races. Moreover, availability of known genotypes with natural resistance to mycotoxin-producing fungi is a prerequisite for the successful breeding program. While it is possible to identify a few genotypes of corn or peanuts that are naturally resistant toAspergillus we do not know whether these antifungal factors are specific toA. flavus. In crops like cotton, there are no known naturally resistant varieties toAspergillus. Availability of transgenic varieties with antifungal traits is extremely valuable as a breeding tool. Several antifungal proteins and peptides are available for genetic engineering of susceptible crop species, thanks to the availability of efficient modern tools to understand and evaluate protein interactions by proteomics of host, and genomics and field ecology of the fungus. Transgenic approaches are being undertaken in several industry and academic laboratories to prevent invasion byAspergillus fungi or to prevent biosynthesis of aflatoxin. Recent trends in reducing aflatoxin contamination through genetic engineering of cultivated crop species with antifungal proteins are summarized in this report.