RAPD Marker Facilitated Analysis of Genetic Diversity among Capsicum Genetic Resources from the Asian Vegetable Research and Development Center

Abstract

Significant effort has been made in the collection of Capsicum germplasm throughout the world for maintenance by genebanks. The largest Capsicum germplasm collection is held by the Asian Vegetable Research and Development Center (AVRDC), consisting of 6844 accessions and eight species. The paradox of any germplasm collection is that, as the number of accessions and the probability of preserving genetic variability increases, the ability of users to efficiently utilize this resource decreases. Genetic variation can be quantified using RAPD molecular marker allele frequency and allelic variation to understand the genetic structure and variation within and among populations. The comprehensive Capsicum collection held at the AVRDC provides an opportunity to sample a range of germplasm representative of the variability that exists in available Capsicum germplasm. Accessions were sampled from the AVRDC collection to represent the range of genetic variation available in Capsicum 1) based on cluster analysis using morphological traits among 1500 accessions and 2) based on pedigree information from the Capsicum breeding program. Our objectives include understanding the structure and magnitude of genetic diversity among these AVRDC accessions and comparing the genetic diversity within sub-populations of these accessions. RAPD fingerprints of these accessions were collected using markers dispersed over numerous linkage groups based on a genetic map we have constructed. RAPD band frequencies and RAPD band diversity were used to test differences among and within sub-populations. The understanding of the distribution of genetic variation among and within these sub-populations will be useful for prioritizing collection, conservation, and sampling of these genetic resources.