COMPARISON OF MEXICAN COMMON BEAN (PHASEOLUS-VULGARIS L.) CORE AND RESERVE GERMPLASM COLLECTIONS

A core collection has been established for the Phaseolus vulgaris germ plasm collection held at CIAT (Centro International de Agricultura Tro pical, Call, Colombia) to facilitate more extensive evaluation and uti lization of the more than 24 000 accessions held in the collection. Th e objective of this study was to contrast the genetic structure of cor e and reserve germplasm accessions sampled from this collection by mol ecular marker and characterization data, A comparison of a random samp le of 90 accessions from the Mexican P. vulgaris core collection and a random sample of 90 Mexican accessions from the reserve collection wa s made based on 224 RAPDs (random amplified polymorphic DNA) add chara cterization of each accession by state in Mexico where collected, grow th habit, primary seed coat color, seed weight, and altitude of collec tion site. RAPD markers were used to compare core and reserve samples based on marker frequencies, marker diversity, and nearest neighbor an d multidimensional scaling analyses of marker-derived genetic distance matrices. No significant differences were found between core and rese rve samples based on marker data. Comparison of core and reserve sampl es for primary seed coat color, growth habit, or state of Mexico where collected also indicated no significant differences. Means and varian ces for seed weight and altitude of collection site mere also not sign ificantly different. Thus, enrichment of diversity was not detected in the core sample. However, the results indicate that the genetic struc ture of the core will be representative of the reserve collection for the common bean collection at CIAT.