Co-segregation analysis and mapping of the anthracnose Co- 10 and angular leaf spot Phg- ON disease-resistance genes in the common bean cultivar Ouro Negro.

Anthracnose (ANT) and angular leaf spot (ALS) are devastating diseases of common bean ( Phaseolus vulgaris L.). Ouro Negro is a highly productive common bean cultivar, which contains the Co- 10 and Phg- ON genes for resistance to ANT and ALS, respectively. In this study, we performed a genetic co-segregation analysis of resistance to ANT and ALS using an F population from the Rudá × Ouro Negro cross and the F families from the AND 277 × Ouro Negro cross. Ouro Negro is resistant to races 7 and 73 of the ANT and race 63-39 of the ALS pathogens. Conversely, cultivars AND 277 and Rudá are susceptible to races 7 and 73 of ANT, respectively. Both cultivars are susceptible to race 63-39 of ALS. Co-segregation analysis revealed that Co- 10 and Phg- ON were inherited together, conferring resistance to races 7 and 73 of ANT and race 63-39 of ALS. The Co- 10 and Phg- ON genes were co-segregated and were tightly linked at a distance of 0.0 cM on chromosome Pv04. The molecular marker g2303 was linked to Co- 10 and Phg- ON at a distance of 0.0 cM. Because of their physical linkage in a cis configuration, the Co- 10 and Phg- ON resistance alleles are inherited together and can be monitored with great efficiency using g2303. The close linkage between the Co- 10 and Phg- ON genes and prior evidence are consistent with the existence of a resistance gene cluster at one end of chromosome Pv04, which also contains the Co- 3 locus and ANT resistance quantitative trait loci. These results will be very useful for breeding programs aimed at developing bean cultivars with ANT and ALS resistance using marker-assisted selection. [ABSTRACT FROM AUTHOR]