RANDOM AMPLIFIED POLYMORPHIC DNA VARIATION WITHIN AND AMONG BEAN LANDRACE MIXTURES (PHASEOLUS-VULGARIS L.) FROM TANZANIA

Genetic characterization of 51 individual pure lines from 13 landraces of three common bean (Phaseolus vulgaris L.) mixtures from the southe rn highlands of Tanzania was undertaken using random amplified polymor phic DNA (RAPD) analysis. A dendrogram generated by cluster analysis f rom data derived from fragments amplified by 12 random 10-base primers divided the bean individuals onto two main branches with less than 60 % genetic similarity. Branches A and B subdivided into two and four cl usters, respectively. Mixture 2, comprising three landraces, was the m ost uniform, most plants appearing on cluster 4 of branch B. Three of the four landraces of mixture 1 appeared on cluster 3 of branch B whil e the fourth landrace appeared on major branch A. Mixture 3 showed the greatest genetic variation with components appearing on both major br anches. The clear separation of the 13 landraces onto two main branche s of the dendrogram together with phenotypic characters, notably varia tion in bean size, suggests that the two groups might represent two di stinct gene pools of P. vulgaris.