A genetic linkage map of Phaseolus vulgaris L. and localization of genes for specific resistance to six races of anthracnose (Colletotrichum lindemuthianum).

A genetic map of common bean was constructed using 197 markers including 152 RAPDs, 32 RFLPs, 12 SCARs, and 1 morphological marker. The map was established by using a F(2) population of 85 individuals from the cross between a line derived from the Spanish landrace Andecha (Andean origin) and the Mesoamerican genotype A252. The resulting map covers about 1,401.9 cM, with an average marker distance of 7.1 cM and includes molecular markers linked to disease resistance genes for anthracnose, bean common mosaic virus, bean golden yellow mosaic virus, common bacterial blight, and rust. Resistance to races 6, 31, 38, 39, 65, and 357 of the pathogenic fungus Colletotrichum lindemuthianum (anthracnose) was evaluated in F(3) families derived from the corresponding F(2) individuals. The intermediate resistance to race 65 proceeding from Andecha can be explained by a single dominant gene located on linkage group B1, corresponding to the Co-1 gene. The recombination between the resistance specificities proceeding from A252 agrees with the assumption that total resistance to races 6, 31, 38, 39, 65, and 357, is organized in two clusters. One cluster, located on B4 linkage group, includes individual genes for specific resistance to races 6, 38, 39, and 357. The second cluster is located on linkage group B11 and includes individual genes for specific resistance to races 6, 31, 38, 39, and 65. These two clusters correspond to genes Co-3/Co-9 and Co-2, respectively. It is concluded that most anthracnose resistance Co- genes, previously described as single major genes conferring resistance to several races, could be organized as clusters of different genes conferring race-specific resistance.