Marker-assisted selection of common beans for resistance to common bacterial blight: efficacy and economics

The possibility of using random amplified polymorphic DNA (RAPD) markers previously mapped in the common bran PC50/XAN159 population to select for resistance to common bacterial blight (CBB) in different populations was examined. Two out of 13 selected RAPD markers were polymorphic in HR67 and W1744d. the parental lines used in this experiment. Cosegregation analysis of the two polymorphic markers and disease reaction in a recombinant inbred (RI) population derived from HR67/W1744d confirmed that one of the two RAPD markers. BC420(900), was significantly associated with a major quantitative trait locus-conditioning resistance to CBB in HR67. This locus accounted for approximately 62% of the phenotypic variation. The RAPD marker was transformed into a sequence characterized amplified region (SCAR) marker and used for selection in a different population derived from 'Envoy'/HR67. Prediction for resistance to CBB with the BC420(900) SCAR marker was 94.2% accurate in this population. A comparison between marker-assisted selection (MAS) and conventional greenhouse screening showed that the cost of MAS is about one-third less than that of the greenhouse test.