Morphological and molecular characterization of cowpea (Vigna unguiculata L. Walp.) genotypes

Abstract

Cowpea [Vigna unguiculata (L.) Walp.], is a legume and one of the most ancient crops known to man and grown in tropical and subtropical regions. Cowpea seeds have a high nutritional value containing high amount of protein (20-25%). Despite of its importance, the utilization of genetic diversity and germplasm characterization in cowpea breeding program has not been fully exploited. Therefore, twelve morphological characters and six polymorphic microsatellite/simple sequence repeat (SSRs) markers were used to analyze genetic diversity in thirty-eight cowpea genotypes. The dendrogram was constructed using UPGMA algorithm and Gower?s dissimilarity values (ranged from 0.0601 to 0.5589) derived from twelve morphological characters. It was grouped in seven clusters showing the most diverse genotypes were CGD 1246 and CGD 1311 (Gower?s distance: 0.5589) and the most similar genotypes were GC 1501 and GC 1601 (Gower?s distance: 0.0601). In molecular characterization, a total of 14 amplicons were detected with a ranged from two to three with an average 2.33 alleles per loci. The mean values of polymorphic information content (PIC) and heterozygosity was 0.319 and 0.399, respectively which are measures of the efficiency of markers for studying polymorphism level available in the cowpea genotypes. Total 224 amplicons were considered for to derive Jaccard?s similarity matrix for the construction of dendrogram (having six clusters) and 2-D PCA (Principal Component Analysis) plot. The morphological characters and SSR markers can be used in diversity analysis and characterization of cowpea genotypes. The per se performing genotypes for individual character can be exploited in population/genotype development of cowpea for the improvement of that particular character. This will provide information to plant breeders for selection of parents to develop populations in cowpea breeding programs.