GENETIC DIVERSITY IN MEXICO OF ‘POBLANO’ PEPPER LANDRACES BY MICROSATELLITES

Abstract

Domestication of chili pepper (Capsicum annuum L.) took place in México, producing large diversity of varieties in the country. ‘Poblano’ pepper is distributed over central México, and it is not consumed by virtue of its capsaicin content, as most of the species of the genus, but by its use as the main ingredient of traditional dishes. In order to describe the different genetic groups composed by varieties, to determine their possible patterns of distribution of diversity, to analyze the genetic structure of ‘Poblano’ pepper populations and their relationships with other pepper types, this study was carried out. The research considered 63 pepper populations: 55 of ‘Poblano’ pepper, 2 of ‘Loco’ pepper, 2 of ‘Miahuateco’ pepper and 3 of ‘Ancho’ pepper, collected from the Puebla Valley, Tehuacán, Puebla and Rancho Grande, Zacatecas, and the commercial hybrid ‘Doroteo” as reference. Nineteen microsatellite (SSR) loci were analyzed for calculating the following genetic diversity parameters: proportion of polymorphic loci, heterozygosity and Wright’s F-Statistics; in addition, principal components and cluster analyses were performed. A total of 105 alleles were detected with an average of 5.53 alleles per locus and 80 % of the loci were found to be polymorphic, with local landraces showing higher polymorphism and heterozygosity. The genetic differentiation F_ST was 0.108, which indicates that 89.2 % of the variation is within populations, with a major differentiation into the ‘Poblano’, ‘Ancho’ and ‘Loco’ pepper types. Populations formed well defined groups, but some dispersion was observed within the ‘Poblano’ group. A high differentiation among varieties from the Puebla Valley, Tehuacán and Zacatecas was detected, aside the commercial hybrid. The genetic complexity was superior within the pepper landraces, which did not show a defined pattern of distribution.