Genetic system for the reaction of Phaseolus vulgaris to the BA-2 (Alpha) race of Colletotrichum lindemuthianum

Abstract

Seven cultivars of the common bean (Phaseolus vulgaris L.) were evaluated for their reaction to the BA-2 (alpha) race of anthracnose (Colletotrichum lindemuthianum [Sacco & Magn.] Scrib.). Parental, F I and F 2 plants from 20 crosses involving resistant and susceptible cultivars were inoculated with this fungus. Genetic resistance to the BA-2 race in the seven bean cultivars can be accounted for by two dominant genes, Are and A, which behave as duplicate factor loci. In addition, interaction of the dominant loci X and Y, belonging to a complementary factor system, confers a resistant reaction to the BA·2 race.