Submitted to: Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 17, 1999
Publication Date: N/A
Interpretive Summary: Plants defend themselves from microbial and insect pests by producing a number of different compounds that are toxic to the invading organism. However these defense mechanisms are often inadequate to protect the plant and need to be supplemented with synthetic, chemical pesticides. Using tobacco as a model system, we have genetically introduced a gene into the plants that enables them to produce a small peptide that has been shown to be toxic to fungal and bacterial plant pathogens. The peptide does not harm mammalian cells at the levels required to kill microbial pathogens. We identified tobacco plants carrying the peptide gene and many of these plants demonstrated increased resistance to attack by both bacterial and fungal pathogens. Successful transfer and expression of the peptide gene in commercially important crop plants such as cotton, peanut and corn will reduce the need for treating these crops with chemical pesticides thus reducing production costs for farmers. Less dependence on chemical pesticides will also be of benefit to the environment.
Technical Abstract: Transgenic tobacco plants producing the synthetic antimicrobial peptide D4E1, encoded by a gene under the control of an enhanced cauliflower mosaic virus 35S RNA promoter, were obtained by Agrobacterium-mediated transformation. Successful transformation was demonstrated by PCR and Southern hybridization analysis of tobacco DNAs. Expression of the synthetic D4E1 gene was shown by RT-PCR of tobacco mRNA. Crude protein extracts from leaf tissue of transformed plants significantly reduced the number of fungal colonies arising from germinating conidia of Aspergillus flavus and Verticillium dahliae by up to 75 percent and 99 percent, respectively, compared to extracts from plants transformed with pBI121. Compared to negative controls, tobacco plants expressing the D4E1 gene showed greater levels of disease resistance in planta to the fungal pathogen, Colletotrichum destructivum, which causes anthracnose.