Estrutura populacional e diversidade genética em acessos de feijão comum e co-segregação dos genes Ur-14 e Co-34/Phg-3 da cultivar ouro negro

Abstract

The genetic improvement of common bean (Phaseolus vulgaris L.) depends on the information of the available germplasm. Similarly, genetic characterization of disease resistance genes and the identification of molecular markers linked to these genes accelerate the common bean breeding process. The objectives of this research were: 1) to study the population structure and genetic diversity of common bean accessions from the Common Bean Germplasm Bank at Núcleo de Pesquisa Aplicada à Agricultura (Nupagri) using SSR (Simple Sequence Repeats) markers; and 2) to investigate the association between the Ur-14 rust resistance gene and Co-34/Phg-3 gene cluster promoting resistance to anthracnose and angular leaf spot in Ouro Negro cultivar using co-segregation analysis and develop SSR markers linked to these resistance genes. The results show that the common bean accessions from the Nupagri Common Bean Germplasm Bank have high genetic diversity and well-defined population structure, distributed between the Andean and Mesoamerican gene pools. The accessions were structured in five distinct subpopulations. Co-segregation analysis revealed that Ur-14 gene and the Co-34/Phg-3 gene cluster were inherited together for resistance to rust and anthracnose/angular leaf spot in Ouro Negro. Genetic mapping involving 18 SSR markers revealed that Ur-14 gene is linked in coupling phase at 0.5 cM from Co-34/Phg-3 loci in Pv04 linkage group. The proximity of the SSR markers to the Ur-14 and Co-34/Phg-3 loci indicates the potential use of these markers for marker-assisted selection in common bean breeding programs developing resistant cultivars to rust, anthracnose and angular leaf spot.