Genetic diversity ofPseudocercospora griseolaresistancelociin common beans

Common bean (Phaseolus vulgarisL.) is one of the most widely grown legumes in the world. Although the crop has high yield potential, average yields in Brazil are low due to several diseases. Angular leaf spot (ALS), caused byPseudocercospora griseola, is among the most important diseases. A set of 81 accessions from the Instituto Agronomico (IAC, Campinas, SP) germplasm bank were evaluated for ALS resistance and genotyped by 12 microsatellites previously associated with ALS QTL resistance. Allele frequencies, number of alleles perlocus, expected heterozygosity (He), and Shannon's Information Index (I) were calculated. The average Ho was 0.12, and the He was 0.54. The STRUCTURE analysis and UPGMA clustering based on Nei's genetic distance indicated a moderate degree of genetic diversity, with 4 and 5 main groups, respectively. Evaluation of the severity of ALS showed that 17% of the accessions had resistance. Cultivars were recommended for breeding crosses aimed at gaining in genetic diversity and resistance to ALS.