Random amplified polymorphic DNA (RAPD) analyses of genetic diversity in chile (Capsicum spp.).

摘要

Genetic diversity of chile (Capsicum spp.) was evaluated via Random Amplified Polymorphic DNA (RAPD) molecular markers. Previous genetic diversity studies at the molecular level in Capsicum have focused primarily on intra-specific comparisons or comparisons of genetically diverse accessions within a species. Evaluation of genetic diversity among accessions relatively similar at the genetic level has not been reported in Capsicum. Genetic diversity in three phenotypically uniform groups of Capsicum germplasm: Bell pepper (C. annuum L. var. annuum) cultivars, C. pubescens Ruiz & Pav. landraces, and wild chile (C. annuum L. var. glabriusculum (Dunal) Heiser & Pickersgill) were evaluated for genetic diversity. These three groups represent different theoretical levels of germplasm genetic diversity. RAPD analysis of each group provided a means of testing theories of genetic diversity within those groups. Additionally, concepts concerning in situ or ex situ conservation methods in Capsicum were addressed.; Genetic diversity in bell pepper cultivars was evaluated. Bell peppers are assumed to contain relatively little genetic diversity among cultivars relative to other Capsicum pod types and species. Additionally there is a concern that a loss of genetic diversity in this pod-type may be occurring. Cultivars available in the mid 1960s were compared to modern commercially available cultivars. Additionally, a subset of two commercially available open-pollinated cultivars, ‘California Wonder’ and ‘Jupiter’, was examined in more detail. The results indicate that no net loss of genetic diversity has occurred in bell pepper cultivars since the 1960s. RAPD analysis also provided a means of evaluating the level of genetic diversity within and among accessions of ‘California Wonder’ and ‘Jupiter’. ‘California Wonder’ was shown to contain greater levels of genetic diversity than ‘Jupiter’, and thus may not be suitable as the standard cultivar for research.; Genetic diversity within and among landrace accessions of C. pubescens was evaluated using RAPD analysis. The results indicated that C. pubescens contained a relatively high level of genetic diversity both within and among accessions, and that genetic diversity is greater in accessions closer to the center of domestication for this species. It is also substantiated that the wild species C. cardenasii and C. eximium are closely related species.; Wild chile, known as chiltepín (Capsicum annuum L. var. glabriusculum) from both in situ and ex situ conservation areas were evaluated for genetic diversity. The results indicate that chiltepín accessions from an in situ conservation area at the northern-most range of their habitat were highly homogenous, both morphologically and genetically, yet were genetically diverse when compared to accessions from Mexico and Guatemala.