GENE POOL CLASSIFICATION OF COMMON BEAN LANDRACES FROM CHILE BASED ONRAPD AND MORPHOLOGICAL DATA

Landraces of common bean (Phaseolus vulgaris L.) from Chile are a phen otypically diverse group whose relationship to the two major gene pool s (Andean and Mesoamerican) is unclear. The genetic composition of 69 Chilean landraces, 15 commercial cultivars grown in Chile, and 11 prev iously characterized check accessions was examined using RAPDs (random amplified polymorphic DNA). The 25 primers used generated 106 polymor phic bands. A genetic distance (GD) matrix based on simple matching of RAPD phenotypes was converted to a two dimensional plot using multidi mensional scaling (MDS). Two major clusters, encompassing most of the accessions, were apparent on the resulting plot and were identified wi th the Andean and the Mesoamerican gene pools. No obvious signs of int rogression or hybridization between gene pools were observed. Clusteri ng analysis using bootstrap samples of the RAPD bands showed that as f ew as 20 randomly chosen bands could classify the accessions into the correct gene pools nearly as well as all 106 bands. In general, the An dean landraces were collected at more northerly latitudes and higher a ltitudes than the Mesoamerican landraces. Morphological data were coll ected for 63 landraces for seven numerical traits and 13 categorical t raits. The morphological data used were to create a distance matrix an d analyzed as with the RAPD data, but no clear separation of the group s was seen. Accessions from the two groups identified by RAPDs differe d significantly for 11 of the 20 traits examined. It was concluded tha t by RAPDs, the Chilean landraces could be readily classified into the Andean and Mesoamerican gene pools. Morphological traits were less ef fective at classification.