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 demonstrated that cultivar MAR-2 was resistant to race 63.39 of P. griseola. The objective of this work was to characterize the resistance to angular leaf spot in MAR-2. in an F-2 population derived from the cross with Ruda (susceptible parent), and also to identify random amplified polymorphic DNA (RAPD) markers linked to the resistance gene. Cultivar MAR-2 was crossed with Ruda, a "carioca-type" cultivar susceptible to angular leaf spot, to determine the inheritance of resistance. The results demonstrated that a single dominant 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 were constructed to identify RAPD markers linked to the resistance gene. Amplification with primer OPE-04 generated a 500-bp fragment which distinguished the resistant from the susceptible bulk populations. Co-segregation analysis of the entire population demonstrated that the RAPD marker was linked to the resistance gene at a distance of 5.8 Cm.