Genetic Mapping of Agronomic Traits in Common Bean

Abstract

SBreeding effort to improve yield and other quantitative traits in common bean (Phaseolus vulgaris L.) has proven to be difficult. The use of molecular markers will improve our understanding of the genetic factors conditioning these traits and is expected to assist in the selection of superior genotypes. This study was conducted to identify genetic loci associated with 14 quantitative traits responsible for seed yield, yield components, and plant architecture traits in common bean. A population of 142 F2:4 lines that was developed from a cross between OAC Seaforth and OAC 95-4, was evaluated at two locations in Canada in 1998. The lines were assayed for random amplified polymorphic DNA (RAPD), restriction fragment length polymorphism (RFLP), simple sequence repeat (SSR), and amplified fragment length polymorphism (AFLP) markers. One hundred fourteen markers were assigned to 12 linkage groups. Growth habit and resistance to common bacterial blight [CBB, caused by Xanthomonas axonopodis pv. phaseoli (Smith) Vauterin, Hoste, Kosters & Swings = syn. X. campestris pv. phaseoli (Smith) Dye] were each mapped as single major genes on linkage groups G11 and G5, respectively. An alignment of the current map with the previous linkage map developed at the University of Florida and the core linkage map of bean was produced from 30 RFLP loci. Twenty quantitative trait loci (QTL) were identified for the 14 traits that were analyzed. The number of QTL identified per trait ranged from one to three. A multiple QTL model for each trait showed that these genomic regions accounted for 11.3 to 43.1% of the total phenotypic variation for the traits. Five of the twenty QTL were detected at both locations. The strengths of QTL effects for a given trait appeared to be slightly different among locations, but the positions of QTL on the map were stable across locations.