Mapping of QTL for Seed Size and Sliape Traits in Common Bean

Bean seed weight and shape are important traits of different market bean classes. One of the first associations found between a genetic marker and a quantitative trait was reported by Sax ( 1923) for the relationship between seed pigmentation {P gene) and seed weight in common bean. More recently three types of molecular markers have been used to study the genetics of seed weight in common bean including isozyme (Vallejos and Chase, 1991), RFLP (Koinange et al, 1996; Nodari, 1992) and seed protein markers (Koinange et al., 1996; Nodari, 1992). Isozyme markers have also been used to study the genetics of seed length and seed height by Vallejos and Chase (1991 ). These studies have contributed to our understanding of the genetics of seed size and shape and offer prospects for the use of molecular markers in the modification or maintenance of seed characteristics in bean breeding programs. In a molecular marker based analysis, Jung et al. ( 1997) detected RAPD markers associated with QTL for resistance to common bacterial bHght (CBB). Our objective was to identify QTL for seed weight, length, and height segregating in a recombinant inbred line (RIL) population derived from the common bean cross 'PC-50' (larger seed weight) x XAN-159 (smaller seed weight).