RAPD and SCAR markers linked to a gene conferring resistance to angular leaf spot in common bean

Angular leaf spot, caused by the fungus Phaeoisariopsis griseola, is one of the most important bean diseases in Brazil. The objectives of this study w ere to determine the inheritance of angular leaf spot resistance and to ide ntify random amplified polymorphic DNA (RAPD) and sequence-characterized am plified region (SCAR) markers linked to the resistance gene present in cv. Cornell 49-242, in a cross between this cultivar and susceptible cv. Ruda. The parents, F-1, F-2 and backcross-derived plants were inoculated with P. griseola pathotype 31-17 under environmentally controlled greenhouse condit ions. The results indicate that one single dominant gene controls the resis tance in Cornell 49-242. Two RAPD markers, OPN 02(890c) and OPE 04(650c), w ere found to be linked in the coupling phase, at 3.2 and 12.5 cM of the res istance gene, respectively. To increase the reproducibility of the detectio n of marker OPN02(890c) it was converted into a SCAR marker. It is proposed that the designation of Phg-2 be used for the angular leaf spot resistant gene present in Cornell 49-242.