Assessment of genetic diversity in cowpea (Vigna unguiculata L.) germplasm using morphological and molecular characterisation

Abstract

Cowpea (Vigna unguiculata L.) is the most important grain legume crop grown in tropical and subtropical regions. Cowpea grain has a high nutritional value containing high amount of protein (23–29%). A total of 32 cowpea genotypes were selected for characterization at molecular and morphological markers under normal irrigation and drought stress conditions separately, as an assisting tool for a reliable varietal selection in breeding programs. In this study 17 morphological characters and multivariable statistical methods were studied and followed by using a set of 22 Simple Sequence Repeat (SSR) primer pairs for molecular characterizations. The analysis of variance for morphological traits revealed significant differences among accessions for all measured traits. In molecular (SSR) analysis, a total of 186 alleles were detected with an average of 2 alleles for each locus, and genetic distance between genotypes was estimated 0.0066. The average genetic distance based on Nei’s index among genotypes was 0.116, and the polymorphism information content value for SSR loci varied from 0.625 for primer Vm5 to 0.25 for primer Vm25 with an average of 0.445. Results of factor analysis determined 5 and 6 factor in drought stress and normal irrigation condition explaining 81.17 and 88.20% of the total variation respectively. The average genetic similarity observed across all the genotypes was 75.8%.

Keywords

• cowpea
• genetic diversity
• ssr
• morphological characters
• molecular marker
• drought stress