Morphological and genetic characterization of bambara groundnut (vigna subterranea (l.) verdc.) landraces in Kenya

Abstract

The existence of genetic diversity in germplasm collections is crucial for cultivar development. The objectives of this study were to determine genetic diversity of bambara groundnut (Vigna subterranea (L) Verdc.) landraces from Kenya using genetic markers and characterize bambara groundnut landraces from Kenya using morphological markers. Genetic and morphological relationships among bambara groundnuts accessions, were evaluated using morphological and microsatellite markers. Twelve Simple Sequence Repeat (SSR) markers were used to analyse the genetic diversity among 105 bambara groundnut germplasms collected from Western Kenya and the Genetic Resources Research Institute (GeRRI) of Kenya. In the genetic diversity twenty four alleles were revealed with a mean of 2 alleles per locus. The polymorphic information content (PIC) and gene diversity values averaged 0.28 and 0.35 respectively indicating low genetic diversity among the evaluated bambara groundnut germplasm. Genetic distance based on Jaccard’s similarity coefficient from the SSR marker analysis ranged from 0.08 to 1.16 among the landraces. Cluster analysis distinctly grouped the 105 accessions into three major clusters. The Analysis of Molecular Variance (AMOVA) revealed that 98% of the total genetic variation was within accessions whereas variation among accessions accounted for 2% of the total genetic variation. Quantitative traits were all statistically significant at (p≤0.05) except for seed weight, seed number per plant and number of stems per plant. The first four principal components accounted for 33.28, 18.39%, 13.32% and 8.17 %, respectively of the morphological variations among the landraces. The landraces were grouped into two distinctive clusters with the second cluster sub-divided into four subclusters. Qualitative traits however accounted for less of the variations. This study is useful for germplasm management and utilization into crop improvement in future breeding efforts