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item Miklas, Phillip - Phil

Submitted to: Proceedings of the International Sclerotinia Workshop
Publication Type: Abstract Only
Publication Acceptance Date: 3/1/2004
Publication Date: 3/10/2004
Citation: Miklas, P.N., Grafton, K.F. 2004. QTL analysis of navy bean-derived resistance to white mold in pinto bean. 2nd Sclerotinia Initiative Annual Meeting, Minneapolis, MN. p. 2.

Interpretive Summary:

Technical Abstract: Pinto bean is the most widely grown dry bean (Phaseolus vulgaris L.) market class in the U.S., averaging 600,000 production acres annually. Pinto bean is extremely susceptible to white mold disease caused by Sclerotinia sclerotiorum (Lib.) de Bary, which is rated the #1 disease plaguing dry bean production in the U.S. Breeding pinto bean with resistance to white mold is difficult, due in part to the paucity of resistance sources in a related Middle American background. 'Bunsi' navy bean is a well known source of resistance to white mold from the Middle American gene pool which could be useful for improving resistance of pinto bean. The objective was to develop a molecular linkage map for the recombinant inbred population (F5:7) derived from a cross between 'Aztec' pinto bean (susceptible to white mold) and ND88-106-04 navy bean (with resistance to white mold derived from Bunsi). The linkage map is being used to identify quantitative trait loci (QTL) conditioning resistance to white mold as measured across four field trials conducted in North Dakota and Washington. So far, 102 markers have been mapped in the Aztec/ND88-106-04 population. The partial linkage map generated to date has revealed QTL (P < 0.01) associated with disease avoidance traits and physiological mechanisms of resistance. Three independent QTL conditioning 14, 13, and 10% of the phenotypic variation for open plant canopy (disease avoidance trait) were identified with stable expression across environments. For physiological resistance mechanisms, two independent QTL for stay-green stem trait, explaining 25 and 15% of the variation were identified. Seven QTL conditioning resistance to white mold in the field, explaining from 9 to 18% of the phenotypic variation, were expressed in single environments. Pinto bean lines with promising levels of white mold resistance obtained in this study are undergoing advanced stages of testing for potential release.