|Rajasekaran, Kanniah - Rajah|
Submitted to: Toxic Microorganisms Symposium Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 6/1/2002
Publication Date: 12/1/2002
Citation: Cleveland, T.E., Rajasekaran, K., Cary, J.W., Chen, Z.-Y., Brown, R.L., Bhatnagar, D., Radin, J.W. 2002. Balancing the benefits and potential risks of using biotechnology to enhance resistance in crops to Aspergillus flavus infection and aflatoxin contamination. In: Pathogenic Microorganisms and Their Toxins: A Global Perspective of Their Risk (Book Chapter). IXth International Symposium, U.S.- Japan Natural Resources Panel on Toxic Microorganisms (UJNR). p. 268-301.
Technical Abstract: Aflatoxins, produced by A. flavus group fungi occur in food and feed crops before harvest and have been shown to be toxic and extremely carcinogenic when ingested by animals and humans. Therefore, much of the research aimed at solving the aflatoxin problem has focused upon identifying technologies to inhibit growth of A. flavus and prevent aflatoxin formation in crops before harvest. These studies have led to the identification of a variety of antifungal peptides, proteins and their genes which are being used in genetic engineering of cotton or as selectable markers in corn breeding to enhance resistance in these crops against A. flavus infection in the field. In addition, a "gene cluster" (over 80 kilobases in size) in A. flavus and A. parasiticus has been identified upon which reside almost all the genes involved in aflatoxin biosynthesis. The regulation of this gene cluster, which is critical in formation of aflatoxin, can now be specifically "targeted" in attempts to interfere with aflatoxin formation in plants. Genetic engineering to suppress fungal invasion of cottonseed has shown preliminary success. For example, in situ assays using immature cottonseeds expressing antifungal transgenes (encoding bacterial chloroperoxidase or a synthetic lytic peptide) and inoculated with a green fluorescent protein-expressing A. flavus strain, showed a reduction in fungal advance in both seed coats and cotyledons. The question of balancing potential risks of using genetic engineering technologies against the benefit of reducing risks of aflatoxin contamination through biotechnology are addressed, an important consideration in the future commercialization of these resistant crops. Added benefits of transgenic crops such as less dependance on chemical pesticides are highlighted.