Genetic Diversity and Population Structure of Kenyan Common Bean (Phaseolus vulgaris L.) Germplasm Using Peroxidase Gene Markers

Abstract

Common bean (Phaseolus vulgaris L.) is a vital legume used as human food, source of cash income, feed for livestock, and it increases the fertility of soil by its ability to fix nitrogen. The aim of this research was to determine the genetic diversity and population structure of 40 common bean germplasm cultivated in Kenya, using peroxidase gene (POX)-based molecular markers. The loci analyzed showed high diversity and amplified 624 alleles, ranging from 3 to 9 on every locus, with an average of 7.20. The PIC of the POX markers varied from 0.6204 to 0.9110, with an average of 0.7677. The range of the observed heterozygosity was from 0.6667 to 0.9150 with a mean of 0.7945, while the values of the mean genetic diversity ranged from 0.3072 to 0.4425 with a mean of 0.3972. The UPGMA phenogram separated the genotypes into two main genetic clusters, and the genotypes showed no grouping by geographical origins. The highest value of genetic variation was observed between the genotypes obtained from Western, Rift valley and Central regions of Kenya. Population structure analysis grouped the germplasm into 7 gene pools and showed that the genotypes have a common genetic lineage. AMOVA revealed higher genetic diversity (99%) within population than among population (1%), and this offers a reliable base for the design of genetic improvement schemes. Results of the present study can be used in future breeding programs and for the genetic improvement in common bean.