Genetic Diversity among Latin American Andean and Mesoamerican Common Bean Cultivars

Abstract

Knowledge of the relationship among existing crop cultivars helps broaden the genetic base of new cultivars, facilitates deployment of useful genes, reduces genetic vulnerability, and maximizes the use of available germplasm resources. In this study, our objective was to analyze the genetic base of common bean (Phaseolus vulgaris L.) cultivars released in Latin America from the onset of breeding activities until 1993. Each of the 203 cultivars of hybrid origin and their 194 ancestors were classified into one of six racial groups: Mesoamerica, Durango, Jalisco, Nueva Granada, Peru, or Chile. Genetic diversity was assessed, based on the pedigree, through the coefficient of parentage (r). The groups of 130 cultivars of Race Mesoamerica and 46 cultivars of Race Nueva Granada both received 79 and 76% of their genes, respectively, from ancestors of their same race. Furthermore, a 55% genetic contribution in the case of Race Nueva Granada cultivars and 41% for Race Mesoamerica was attributed to 12 and 10 ancestors of the same race, respectively. The 18 cultivars of Race Durango received 18% of their genes from Race Nueva Granada; the genetic contribution from their same race was as much as 43%. The three cultivars of Race Chile received half of their genes from Race Chile; the other half came from Races Nueva Granada, Mesoamerica, and Durango. Races Jalisco and Peru received little or no improvement and were used little in the improvement of cultivars of other races. When cultivars were grouped by different time periods, the increasing trend of using interracial hybridizations to broaden the genetic base of cultivars of Races Mesoamerica and Nueva Granada became evident.