Transgenic expression of a gene encoding a synthetic antimicrobial peptide results in inhibition of fungal growth in vitro and in planta.

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 and 99%, 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.