MOLECULAR-MARKER-BASED GENETIC-ANALYSIS OF TEPARY BEAN-DERIVED COMMONBACTERIAL-BLIGHT RESISTANCE IN DIFFERENT DEVELOPMENTAL STAGES OF COMMON BEAN

Randomly amplified polymorphic DNA (RAPD) molecular markers were used to construct a partial genetic linkage map in a recombinant inbred pop ulation derived from the common bean (Phaseolus vulgaris L.) cross PC- 50 x XAN-159 for studying the genetics of bacterial disease resistance in common bean. The linkage map spanned 426 cM and included 168 RAPD markers and 2 classical markers with 11 unassigned markers. The sevent y recombinant inbred lines were evaluated for resistance to two strain s of common bacterial blight [Xanthomonas campestris pv,phaseoli (Smit h) Dye] (Xcp). Common bacterial blight (CBB) resistance was evaluated for Xcp strain EK-11 in later-developed trifoliolate leaves and for Xc p strains, DR-7 and EK-11, in first trifoliolate leaves, seeds, and po ds. One to four quantitative trait loci (QTLs) accounted for 18% to 53 % of the phenotypic variation for traits. Most significant effects for CBB resistance were associated with one chromosomal region on linkage group 5 and with two regions on linkage group 1, of the partial linka ge map. The chromosomal region (a 13-cM interval) in linkage group 5 w as significantly associated with resistance to Xcp strains DR-7 and EK -11 in leaves, pods, and seeds. The regions in linkage group 1 were al so significantly associated with resistance to both Xcp strains in mor e than one plant organ. In addition, a seedcoat pattern gene (C) and a flower color gene (nu(lae)) were mapped in linkage groups 1 and 5, re spectively, of the partial linkage map, The V locus was found to be li nked to a QTL with a major effect on CBB resistance.