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 were to determine the inheritance of angular leaf spot resistance and to identify random amplified polymorphic DNA (RAPD) and sequence-characterized amplified 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 sub(1), F sub(2) and backcross-derived plants were inoculated with P. griseola pathotype 31-17 under environmentally controlled greenhouse conditions. The results indicate that one single dominant gene controls the resistance in Cornell 49-242. Two RAPD markers, OPN 02 sub(890c) and OPE 04 sub(650c), were found to be linked in the coupling phase, at 3.2 and 12.5 cm of the resistance gene, respectively. To increase the reproducibility of the detection of marker OPN02 sub(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.