Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Abstract Only
Publication Acceptance Date: January 7, 2002
Publication Date: February 28, 2002
Citation: Rajasekaran, K., Cary, J.W., Cleveland, T.E. 2002. Control of pathogenic and mycotoxigenic fungi by transgenic cotton plants expressing a synthetic peptide [abstract]. Proceedings of Beltwide Cotton Conference, Atlanta, GA. Technical Abstract: Transgenic cotton plants expressing a gene coding for the synthetic peptide D4E1 have been identified through PCR and RT-PCR. The disease-resistant phenotype of transgenic plants expressing D4E1 is very promising. For example, in vitro assay results using crude leaf extracts from transformed cotton plants (R0 and R1) showed significant inhibition of the growth of pre-germinated spores of Verticillium dahliae, a cotton wilt pathogen that is very sensitive to D4E1. In a similar in vitro assay for the aflatoxin-producing fungus, Aspergillus flavus, leaf extracts from transgenic cottons reduced the number of colony forming units although the results were not highly significant compared to controls. In situ assays using immature cottonseeds, inoculated with Green Fluorescent Protein-expressing A. flavus strain, showed that the transgenic plants are capable of delaying and/or reducing the fungal advance in both seed coat and cotyledons. Detection and quantification of this small peptide (17 AA) in transgenic plant extracts poses a technical problem and availability of suitable antibodies is lacking thus far. Currently, we are increasing seed from R1 progeny to assay for resistance to seedling diseases caused by any one of the following pathogens: Pythium, Fusarium, Rhizoctonia solani, or Thielaviopsis basicola. We are also in the process of producing transgenic plants with stacked genes (providing insect and disease resistance) that will provide an additional level of protection from A. flavus by reducing bollworm damage in cotton bolls, a point of entry for the mycotoxigenic fungus.