Association Mapping of Angular Leaf Spot and Anthracnose Resistance Loci in Common Bean

The common bean is the world’s most important food legume for the human diet. Anthracnose (ANT) and Angular leaf spot (ALS) cause major yield losses in the common bean. This work aimed to perform associative mapping study with common bean genotypes from a diversity panel using SSRs and SNPs with anthracnose and angular leaf spot resistance loci. In this study, 180 accessions of common bean were used. In all experiments, a randomized complete block design with four repetitions was performed, using 4 plants per genotype in each replicate. ANT (race 4) and ALS (race 0-39) were evaluated using a diagrammatic CIAT (Cali, Colombia) scale of 1–9 notes. Association mapping analyses were performed using the MLM (mixed linear model) with the Tassel 2.1 program. For SSRs, it was possible to verify that the LD (linkage disequilibrium) extends to 100 cM showing that common bean has a high extension LD, as expected for an autogamous species. For SNPs, it was possible to detect a rapid decay in the LD, despite of having demonstrated a high LD in various genome regions. A total of 17 associations were established between SSRs with anthracnose resistance loci and 6 SSRs associated with angular leaf spot resistance loci. For SNPs, a total of 14 associations with anthracnose were found, while 10 SNPs associated with angular leaf spot. This study demonstrated the usefulness of the association mapping approach with a reasonable number of markers distributed across the genome to locate resistance disease loci in common bean.