Genetic Diversity of Dry Bean (Phaseolus vulgaris L.) Accessions of Kenya Using SSR Markers

Aims: To determine the genetic diversity existing within the Kenyan dry bean using SSR markers.

Place and Duration of Study: This study was conducted in Western Kenya and Bangor University, North Wales, between September 2010 and December 2012.

Methodology: Thirty five (35) marketable dry bean samples collected from farmers, market centers as well as seed stockists were subjected to SSR analysis. Data generated was subjected to analysis with the GenAlEx 6.4 software assuming Hardy-Weinberg equilibrium to determine gene diversity index, number of polymorphic loci and alleles, genetic distances, analysis of molecular variance (AMOVA) and principal components analysis (PCA). NYTS-pc 2.1 software was used to construct an unweighted pair group method arithmetic averages (UPGMA) dendogram using the generated similarity coefficients.

Results: Of the 7 SSR primers tested, 5 SSR primers were found to be polymorphic and used to screen the bean samples. The 5 primer combinations generated 49 polymorphic bands in 35 samples. Analysis of molecular variance accredited 8% of the disparity to diversity among the populations while the majority of the diversity (92%), resided within populations. The gene diversity index ranged from 0.1267 in the market population to 0.2377 in the Western province population. The highlands of Eastern province had a gene diversity index of 0.1475 while the dry lands had 0.1991. Cluster analysis segregated the bean samples into 9 clusters.

Conclusion: There exists considerable variation in the dry bean of Kenya that is narrowing. There is need to intensify efforts to broaden the bean variation for sustainability. The population genetics of dry beans of Kenya are a possible guide to future bean breeding and germplasm management in Kenya.