Comparison of Mexican common bean (Phaseolus vulgaris L.) core and reserve germplasm collections

A core collection has been established for the Phaseolus vulgaris germplasm collection held at CIAT (Centro International de Agricultura Tropical, Call, Colombia) to facilitate more extensive evaluation and utilization of the more than 24 000 accessions held in the collection. The objective of this study was to contrast the genetic structure of core and reserve germplasm accessions sampled from this collection by molecular marker and characterization data, A comparison of a random sample of 90 accessions from the Mexican P. vulgaris core collection and a random sample of 90 Mexican accessions from the reserve collection was made based on 224 RAPDs (random amplified polymorphic DNA) add characterization of each accession by state in Mexico where collected, growth habit, primary seed coat color, seed weight, and altitude of collection site. RAPD markers were used to compare core and reserve samples based on marker frequencies, marker diversity, and nearest neighbor and multidimensional scaling analyses of marker-derived genetic distance matrices. No significant differences were found between core and reserve samples based on marker data. Comparison of core and reserve samples for primary seed coat color, growth habit, or state of Mexico where collected also indicated no significant differences. Means and variances for seed weight and altitude of collection site mere also not significantly different. Thus, enrichment of diversity was not detected in the core sample. However, the results indicate that the genetic structure of the core will be representative of the reserve collection for the common bean collection at CIAT.