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 southern highlands of Tanzania was undertaken using random amplified polymorphic DNA (RAPD) analysis. A dendrogram generated by cluster analysis from 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 clusters, respectively. Mixture 2, comprising three landraces, was the most 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 while the fourth landrace appeared on major branch A. Mixture 3 showed the greatest genetic variation with components appearing on both major branches. The clear separation of the 13 landraces onto two main branches of the dendrogram together with phenotypic characters, notably variation in bean size, suggests that the two groups might represent two distinct gene pools of P. vulgaris.