Characterization of the Angular Leaf Spot Resistance Gene Present in Common Bean Cultivar Ouro Negro

Angular leaf spot (ALS), incited by the fungus Pseudocercospora griseola, is a major disease affecting common bean. Important resistance sources have been identified and characterized: AND 277, BAT 332, Cornell 49-242, MAR-2, and Mexico 54. P. griseola presents high physiological variability. The control of this kind of pathogen requires continuous evaluation, including monitoring and characterization of pathogenic variability, and eventual germplasm introgression of genes in adapted cultivars. Cultivar Ouro Negro is currently being used as an ALS resistance source in Brazil. This work aimed to characterize the ALS resistance gene present in cultivar Ouro Negro in relation to the other five resistance sources. These cultivars were crossed with ‘Ouro Negro’ (allelism tests) and with susceptible cv. Rudá (inheritance studies) and their segregation patterns were evaluated. The inheritance studies and the allelism tests indicate that ‘Ouro Negro’ harbors at least one resistance locus which is distinct from those present in the other resistance sources.