Genetic relatedness of mexican common bean cultivars revealed by microsatellite markers

Mexico has various types of common bean (Phaseolus vulgaris L.) and a long history of breeding in multiple commercial classes. In this study, our goal was to evaluate a wide collection of commercial cultivars of common beans from Mexico, including Azufrado, Bayo, Flor de Mayo, Flor de Junio, Pinto, and black bean types, to discover their level of relatedness with 32 simple sequence repeat (SSR) markers. Eight panels of end-labeled fluorescent SSR loci were used in an automated detection system and 85% of loci were read. A total of 204 alleles were detected in the study, showing the diversity among the Mexican cultivars. Through population structure and principal components analyses, Andean and Mesoamerican genotypes as well as three subgroups within the Mesoamerican genepool were distinguished. The divisions corresponded to a group of Andean cultivars, two subgroups of the Durango-Jalisco (DJ) complex, and one group equivalent to race Mesoamerica. This latter race was much less diverse than the DJ complex and had little gene flow with other groups. This study shows the value of fluorescent SSR markers for evaluating commercial cultivars of common beans. Given the importance of Mexico as a primary center of origin for common beans, as a major market for the crop, and as the second largest producer in Latin America, this study has implications for the global evaluation of common bean cultivars.