1a. Objectives (from AD-416):
Utilizing results of our prior research in potato where we described the role of xyloglucan-specific endoglucanase genes and xylogucan-specific endoglucanase inhibitor proteins (XEGIP) in Phytophthora host-pathogen interaction, we will identify, characterize and clone XEGIP encoding genes in the Phytophthora resistant pepper CM 334 and evaluate their efficacy against Phytophthora species infection in transgenic tomato and potato. We expect that the XEGIP gene pool from pepper line CM334 will be a valuable resource for developing potential resistance to Phytophthora infestans, and P. capsici in tomato, and to P. infestans and P. erythroseptica in potato.
1b. Approach (from AD-416):
ARS has acquired the basic genetic knowledge of XEGIP encoding genes in potato. This information will be used by both parties to jointly identify potential XEGIP encoding genes in pepper. The Cooperator has access to the CM334 pepper line and control plants, and has samples that have been inoculated with P. capsici. The Cooperator will identify genomic and/or cDNA clones of pepper XEGIP genes for use in transgenic tomato and potato development. XEGIP gene expression studies will also be performed by real–time PCR or microarray analysis.
3. Progress Report:
One method plants have available for reducing damage caused by infecting pathogens is the production of inhibitor proteins. These proteins inhibit the enzymes used by pathogens to damage plant cell walls. A newly characterized inhibitor protein is XEGIP, which inhibits a specific pathogen endoglucanase. We have found multiple copies of this inhibitor in Solanaceous plants, and initiated investigations of their role in a pepper that is highly resistant to root infection by Phytophthora. Two XEGIP genes have been identified and sequenced from pepper transcripts. Recent identification of a gene cluster in potato is being used to determine if a similar cluster exists in pepper. Gene identification will be followed by functional testing and application by breeders and other scientists to improve disease resistance.