Poster: Plant-pathogen interactions

Abs # 532: Genetic and Physiological Basis of Partial Resistance to Sclerotinia sclerotiorum in Phaseolus coccineus

Presenter:	Chipps, Timothy J, chippst@onid.orst.edu
Authors	Stotz, Henrik U (A)   Chipps, Timothy J (B)   Gilmore, Barbara  (A)   Myers, James R (A)
Affiliations:	(A): Oregon State University (B): Oregon Health Science University
Web Site:	http://www.science.oregonstate.edu/~stotzhe/index.html

Scarlet runner beans (Phaseolus coccineus) are a potential genetic resource to transfer partial white mold (Sclerotinia sclerotiorum) resistance to common bean (P. vulgaris). We have identified the P. coccineus accessions PI 255956 and PI 535278 as the most promising resource for mapping and introgressing resistance traits. The F2 generation of a cross between susceptible Wolven Pole and PI 255956 segregated into 50 resistant and 138 susceptible plants. Partial white mold resistance is quantitatively inherited and mapping suggests QTL to be located on linkage groups 3, 7, 8, 11, 12, and 14. Physiological analysis of partial resistance in PI 255956 and PI 535278 suggests a role of oxalate tolerance in resistance to S. sclerotiorum. Specifically, PI 255956 is significantly less sensitive to exogenous oxalate than Wolven Pole. Oxalate concentrations were similar in infected stem tissues of the partially resistant lines and lower than in Wolven Pole PI 255956 and PI 535278 express more oxalate oxidase than Wolven Pole. Thus, oxalate oxidase expression can only partially explain the elevated oxalate tolerance of PI 255956.