Assessment Of The Genetic Diversity Of Cultivated Common Beans (Phaseolus Vulgaris L.) From Cameroon And Kenya Using Allozymes Markers

In order to provide essential information for plant breeding and crop improvement programs, genetic diversity assessment is a prerequisite. In this study, starch gel electrophoresis of 9 enzyme systems encoding 19 putative loci was used to assess allozyme diversity of 13 cultivated common bean (Phaseolus vulgaris) accessions from Cameroon and 21 from Kenya. Results of genetic variation among the studied accessions revealed 26.32% as proportion of polymorphic loci (P), 1.263 as average number of alleles per locus (A), 0.007 as observed heterozygosity (H-O) and 0.079 as the total expected heterozygosity (H-T). The level of genetic diversity within and among the various accessions were H-S = 0.014 +/- 0.003 and D-ST = 0.065 +/- 0.013 respectively. G-statistics estimation indicated a high level of genetic heterogeneity between accessions (G(ST)= 0.825 +/- 0.021), suggesting that cultivated P. vulgaris maintains about 82.5 % of its genetic variation among accessions. This distribution was more pronounced in Kenyan accessions (89.2 %) compared to Cameroonian accessions (69.9%). Important deviation from Hardy-Weinberg expectations was reported in this study (F-IT = 0.903 +/- 0.018). This genetic disequilibrium is likely due to either high genetic differentiation between accessions (FST= 0.861 +/- 0.023) or significant nonrandom mating within accessions (F-IS = 0.233 +/- 0.096). There was no significant gene flow among cultivated P. vulgaris accessions in Cameroon (Nm = 0.058 +/- 0.029) and in Kenya (Nm = 0.045 +/- 0.041).