Inheritance of angular leaf spot resistance in common bean and identification of a RAPD marker linked to a resistance gene

Angular leaf spot, caused by Phaeoisariopsis griseola (Sacc.) Ferraris, is one of the major diseases affecting the common bean (Phaseolus vulgaris L.) in Brazil which can lead to severe yield losses. Previous studies demonstr ated that cultivar MAR-2 was resistant to race 63.39 of P. griseola. The ob jective of this work was to characterize the resistance to angular leaf spo t in MAR-2. in an F-2 population derived from the cross with Ruda (suscepti ble parent), and also to identify random amplified polymorphic DNA (RAPD) m arkers linked to the resistance gene. Cultivar MAR-2 was crossed with Ruda, a "carioca-type" cultivar susceptible to angular leaf spot, to determine t he inheritance of resistance. The results demonstrated that a single domina nt gene present in MAR-2 was responsible for the resistance to P. griseola, rare 63.39. Resistant and susceptible DNA bulks from the F-2 population we re constructed to identify RAPD markers linked to the resistance gene. Ampl ification with primer OPE-04 generated a 500-bp fragment which distinguishe d the resistant from the susceptible bulk populations. Co-segregation analy sis of the entire population demonstrated that the RAPD marker was linked t o the resistance gene at a distance of 5.8 Cm.