Wisniewski, M., USDA, ARS, Kearneysville, WV 25430, United States
Bassett, C., USDA, ARS, Kearneysville, WV 25430, United States
Artlip, T., USDA, ARS, Kearneysville, WV 25430, United States
Janisiewicz, W., USDA, ARS, Kearneysville, WV 25430, United States
Norelli, J., USDA, ARS, Kearneysville, WV 25430, United States
Goldway, M., MIGAL, Galilee Technological Center, Rosh Pina, Israel
Droby, S., ARO, Volcani Center, Bet Dagan, Israel

A portion of our research involves developing methods to enhance the activity of yeast biocontrol agents. In the present study, we describe the cloning and characterization of defensin genes from bark tissues of peach and apple. The open reading frame of both genes code for proteins related to the defensins, a family of highly antimicrobial proteins. Sequence comparison of the encoded proteins revealed significant homology between the peach and apple defensins and defensins from other plant species. RNA gel blot analysis and semi-quantitative-PCR indicated that the genes are seasonally-expressed in bark tissues of one-year-old shoots, and the peach defensin is also expressed in early fruit development. A recombinant version of the peach defensin gene, rDFNl was expressed in the yeast, Pichia pastoris. It was found that rDFNl inhibited germination of the fungal pathogens Pénicillium expansum and Botrytis cinerea. The potential of using defensin genes to enhance biocontrol yeasts is discussed.