Common bean lines as potential differential cultivars for race 65 of Colletorichum lindemuthianum

Abstract

Colletotrichum lindemuthianum, which is known for its wide diversity in virulence, is the causal agent of anthracnose of common bean (Phaseolus vulgaris). Studies of race characterization using the standard set of 12 differential cultivars have shown the predominance of race 65 in Minas Gerais state (Brazil). However, the presence of genetic variability within race 65 has complicated the development of a durable resistant bean cultivar. Therefore, the objective of this study was to identify common bean lines able to differentiate the variation within race 65 to complement the results of the standard set of differential cultivars. A total of 12 common bean lines adapted to Brazilian conditions and 12 fungal isolates classified as race 65 were used. We now propose a new nomenclature to identify the pathogenic variability of race 65 isolates. Using this methodology, five different reaction patterns were observed, allowing the differentiation of regionally important races that could not be discriminated using the standard set of differential cultivars. Furthermore, our approach makes it possible the identification of new genes and sources of resistance to anthracnose.