Submitted to: Plant Molecular Biology International Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: July 30, 2003
Publication Date: September 1, 2003
Citation: Rajasekaran, K., Cary, J.W., Cleveland, T.E. 2003. Disease resistance conferred by the expression of a gene encoding a synthetic peptide in transgenic cotton (Gossypium hirsutum L.) plants. Plant Molecular Biology International Conference Proceedings. S10-57:155. Technical Abstract: We have shown that the transgenic expression of a linear, amphipathic, synthetic, lytic peptide (D4E1) offers the potential for the control of the aflatoxigenic Aspergillus flavus and other microbial phytopathogens for the following reasons. 1) purified D4E1 controlled A. flavus (IC50 = 10 uM) and several other microbial pathogens, including vascular pathogens of cotton. 2) Crude protein extracts from leaf tissue of transgenic tobacco plants expressing the peptide significantly reduced the fungal colonies arising from germinated conidia of A. flavus and Verticillium dahliae. 3) Transgenic tobacco plants expressing D4E1 showed increased resistance in planta to the anthracnose-causing fungal pathogen, Colletotrichum destructivum. 4) Crude extracts from transgenic cotton callus and leaf tissue showed control of A. flavus although the results were not significant with leaf extracts. 5) In situ assays with immature cottonseeds, inoculated with a GFP-expressing A. flavus strain, showed that the transgenic cottonseeds are capable of delaying and reducing the fungal advance in both seed coat and cotyledons, as measured by the GFP fluorescence. Based on these antimicrobial assays and molecular assays, several transgenic lines (R1) were selected and evaluated for resistance in planta to the phytopathogen, Thielaviopsis basicola (IC50 = 0.5 uM) that causes black root rot in emerging seedlings. The results were compared with control, transgenic seedlings expressing the GUS marker gene only. A greater percentage of transgenic progeny seedlings escaped severe damage by T. basicola whereas majority of the control seedlings succumbed to the disease. The fresh weight of transgenic seedlings was significantly higher than that of controls.