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ARS Home » Southeast Area » New Orleans, Louisiana » Southern Regional Research Center » Food and Feed Safety Research » Research » Publications at this Location » Publication #135603
Title: DISEASE RESISTANT TRANSGENIC COTTON TO PREVENT PREHARVEST AFLATOXIN CONTAMINATION

Author
item Rajasekaran, Kanniah - Rajah
item Jacks, Thomas
item Cary, Jeffrey
item Cleveland, Thomas

Submitted to: Proceedings of Int'l Association of Plant Tissue Culture and Biotechnology
Publication Type: Proceedings
Publication Acceptance Date: 8/1/2002
Publication Date: 2/1/2003
Citation: Rajasekaran, K., Jacks, T.J., Cary, J.W., Cleveland, T.E. 2003. Disease resistant transgenic cotton to prevent preharvest aflatoxin contamination. In: Vasil, I.K., editor. Plant Biotechnology 2002 and Beyond, Proceedings of 10th International Association of Plant Tissue Culture and Biotechnology Congress. Dordrecht, The Netherlands: Kluwer Academic Publishers. p. 147-150.

Interpretive Summary: Mycotoxin contamination is a major problem in food and feed crops such as corn, cotton, peanut, and tree nuts. We are developing transgenic cottons that resist the aflatoxigenic fungus, Aspergillus flavus. Crop losses due to pathogens result in economic plus food and feed safety concerns. Transgenic cottons engineered to express antifungal genes not only delay or inhibit mycotoxin-producing A. flavus but also provide a built-in resistance to other foliar and root pathogens. In this report, we have summarized our findings on the novel utility of two gene constructs - a bacterial non-heme chloroperoxidase gene and a linear synthetic peptide for control of disease causing microbes, including saprophytic mycotoxigenic fungi in laboratory- and seedling assays. Continued effectiveness of these gene constructs in transgenic cotton plants under field condition is yet to be evaluated. The principal users of information will be breeders and scientists involved in related research and those in the biotechnology industry.

Technical Abstract: We are developing transgenic cottons that are resistant to the saprophytic fungus Aspergillus flavus, which produces carcinogenic aflatoxin on lipid-rich cottonseed. Several independently transformed lines of cotton expressing antifungal genes coding for either the chloroperoxidase (CPO-P) or the synthetic, linear peptide D4E1 (17aa) have been produced in our laboratory by the Agrobacterium method. In vitro assays using crude leaf extracts from transformed cotton plants (R0 and R1) demonstrated reduced number of colonies from pre-germinated spores of A. flavus, Fusarium moniliforme, and Verticillium dahliae. In situ assays using immature cottonseeds, inoculated with a virulent, Green Fluorescent Protein-expressing A. flavus strain showed that the transgenic plants are capable of delaying and reducing the fungal advance in seed coat and cotyledons. We are currently in the process of evaluating in planta resistance in R1 progeny against one or many cotton pathogens. Preliminary results showed improved resistance to a seedling diseases caused by the vascular pathogen, Thielaviopsis basicola. The advantages of transgenic approaches in broad-spectrum control of phytopathogens including mycotoxin-producing fungi are highlighted. We are developing transgenic cottons that are resistant to the saprophytic fungus Aspergillus flavus, which produces carcinogenic aflatoxin on lipid-rich cottonseed. Several independently transformed lines of cotton expressing antifungal genes coding for either the chloroperoxidase (CPO-P) or the synthetic, linear peptide D4E1 (17aa) have been produced in our laboratory by the Agrobacterium method. In vitro assays using crude leaf extracts from transformed cotton plants (R0 and R1) demonstrated reduced number of colonies from pre-germinated spores of A. flavus, Fusarium moniliforme, and Verticillium dahliae. In situ assays using immature cottonseeds, inoculated with a virulent, Green Fluorescent Protein-expressing A. flavus strain showed that the transgenic plants are capable of delaying and reducing the fungal advance in seed coat and cotyledons. We are currently in the process of evaluating in planta resistance in R1 progeny against one or many cotton pathogens. Preliminary results showed improved resistance to a seedling diseases caused by the vascular pathogen, Thielaviopsis basicola. The advantages of transgenic approaches in broad-spectrum control of phytopathogens including mycotoxin-producing fungi are highlighted.