Submitted to: Bean Improvement Cooperative Annual Report
Publication Type: Research Notes
Publication Acceptance Date: October 1, 2005
Publication Date: February 1, 2006
Citation: Miklas, P.N. 2006. Marker-assisted backcross selection for resistance to sclerotinia white mold in pinto and great northern bean. Bean Improvement Cooperative Annual Report. 49:67-68. Technical Abstract: Resistance to white mold (Sclerotinia sclerotiorum) in dry bean (Phaseolus vulgaris) is quantitatively inherited with low heritability. The identification of QTL conferring resistance may enable MAS to combine resistance sources and expedite development of resistant cultivars. Our objective was to backcross white mold resistance linked QTL markers into pinto and great northern bean. A QTL on linkage group B7 conferring white mold resistance linked with Phs SCAR marker from G 122 source was introgressed by marker-assisted backcrossing (MAS-BC) into ‘Winchester’ pinto bean, and another QTL on B8 linked with RAPD and SCAR markers SS18, AW9, and C5 from NY6020-4 source was similarly transferred by MAS-BC into ‘Maverick’ pinto and ‘Mayflower’ great northern bean. Resulting BCnF4:6 lines from five populations were screened for the markers and for reaction to white mold in the greenhouse straw test and in replicated field trials. The markers effectively transferred the resistance QTL into the recurrent parents. Presence/absence of the marker equated to a difference of 1 unit of disease score. No linkage drag due to presence of the markers was observed, but overall yield was depressed in the MAS BC-lines compared to the recurrent parents. Overall results indicate that MAS-BC of QTL has potential to compliment phenotypic selection in breeding pinto and great northern bean for improved white mold resistance.