ARS | Publication request: OVEREXPRESSION OF A PEACH DEFENSIN GENE CAN ENHANCE THE ACTIVITY OF POSTHARVEST BIOCONTROL AGENTS

Submitted to: International Society for Horticultural Science Meeting
Publication Type: Abstract Only
Publication Acceptance Date: June 1, 2004
Publication Date: June 6, 2004
Citation: Wisniewski, M.E., Droby, S., Bassett, C.L., Janisiewicz, W.J., Artlip, T.S. Overexpression of a peach defensin gene can enhance the activity of postharvest biocontrol agents. International Society for Horticultural Science Meeting. Abstract S10-07 presented at the ISHS Postharvest Workshop, Verona, Italy, June 6-11, 2004.

Technical Abstract: A defensin gene (PpDfn1) was cloned from a cDNA library of peach bark tissues collected in midwinter. The open reading frame of 237 bp codes for a 79 amino acid peptide related to the defensin family of proteins. The gene is seasonally expressed in bark tissues and is also expressed in early fruit development. A recombinant version rDFN1 was expressed in the yeast, Pichia pastoris. It was found that rDFN1 inhibited germination of the postharvest pathogens, Penicillium expansum and Botrytis cinerea. Partially-purified peach defensin protein obtained from the recombinant yeast strains also exhibited antimicrobial activity. Constitutive expression of a defensin in a selected yeast antagonist may be a suitable approach to augment postharvest biocontrol efficacy. One drawback in the use of the peach defensin gene, however, is that it exhibited fungistatic rather than fungicidal activity. Additionally, this approach would require the development of a transformation for a microbial antagonist identified as having antagonistic activity since the antagonist must be extremely well adapted to compete against the pathogen in the ecological niche of fruit wounds. Such a transformation system exists for the biocontrol yeast, Candida oleophila, the antagonist used in the product, Aspire. Recombinant studies utilizing peach defensin are in progress.