Poster: Plant Pathogen/Symbiont Interactions

Abs # 752: Molecular genetics of resistance to Phytophthora capsici in pepper (Capsicum annuum).

Presenter:	Ogundiwin, Ebenezer A., ebenezer@csufresno.edu
Authors	Ogundiwin, Ebenezer A. (A)   Scott, Pamela E. (A)   Donnely, Linda M. (A)   Prince, James P. (A)
Affiliations:	(A): California State University, Fresno.

Root rot and foliar blight is a serious disease of pepper caused by Phytophthora capsici. As part of efforts to assist breeders in developing resistant pepper varieties, we are studying the genetics of resistance to this fungus at the molecular level. We are utilizing two separate pepper mapping populations segregating for resistance to the disease. The first population is a set of 94 recombinant inbred lines (RILs) from the cross Psp11 (susceptible pepper line) x PI201234 (resistant), provided by Dr. Terry Berke and Dr. Lowell Black (formerly of AVRDC). The second is an F₂ population obtained by crossing Joe E Parker (a susceptible line) to Criollo de Morelos 334 (resistant). Linkage maps were constructed for these populations using random amplified polymorphic DNA (RAPD), amplified fragment length polymorphism (AFLP), resistance gene analog (RGA) and morphological markers. The two maps were used to detect quantitative trait loci (QTL) involved with resistance. The RIL population yielded five QTL controlling between 10.1 to 24.4% of the total variation. A total of eight QTL were detected on the linkage map obtained from the F₂ population controlling between 7.5 to 24.5% of the total variation. To date, no RGAs have mapped to any of our QTL. Some molecular markers were common to both maps, and efforts are underway to include RFLP and SSR markers in order to facilitate construction of a consensus map and comparisons with other resistance genes in the Solanaceae. These QTL should be useful in marker-assisted breeding of P. capsici-resistant pepper cultivars.