ARS | Publication request: GENETIC ENGINEERING OF COTTON TO CONFER RESISTANCE TO THE FUNGAL PATHOGEN ASPERGILLUS FLAVUS

Submitted to: Southern Association of Agricultural Scientists Bulletin of Biochemistry and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 21, 2003
Publication Date: August 28, 2003
Citation: Chlan, C.A., Manuel, R., Rajasekaran, K., Cary, J.W., Cleveland, T.E., Guo, J. 2003. Genetic engineering of cotton to confer resistance to the fungal pathogen aspergillus flavus. Southern Association of Agricultural Scientists Bulletin of Biochemistry and Biotechnology. 16:12-19.

Interpretive Summary: Cottonseed is a valuable by-product of the cotton industry with an annual value between 500 and 700 million dollars in the United States. It is used in animal feed and to produce cottonseed oil for human consumption. Both marketability and profitability are greatly diminished when cottonseed that has been infected with toxigenic strains of Aspergillus flavus becomes contaminated with aflatoxin. We are using genetic engineering to develop cotton with enhanced resistance to A. flavus with the goal of reducing aflatoxin levels in cottonseed. Towards this goal, we have developed cotton transformation and regeneration systems, developed model systems to test the efficacy of potential anti-flavus gene products in vitro and in vivo, identified several potential resistance genes, and initiated studies in transgenic cotton. The research will benefit biotechnology scientists and plant breeders involved in genetic modification of important crops for improved disease resistance and food and feed safety.

Technical Abstract: Preharvest contamination of cottonseed with toxic levels of aflatoxin is a serious problem for the cottonseed industry. We have identified and purified a cotton class I chitinase fraction that contains three isoelectric forms with pIs of 5.8, 6.2, and 7.0. This purified fraction was tested for the ability to inhibit the aflatoxin-producing fungus, Aspergillus flavus. Preliminary results indicate that the cotton chitinase extract significantly inhibits A. flavus germination compared to controls. The major component in this extract has a pI of 7.0. We are in the process of transforming cotton with this gene construct driven by a 613 bp cotton vicillin promoter fragment for seed-specific expression.