Genetic analysis indicates a relationship of cowpea (Vigna unguiculata) accessions from Oman to cowpea in the Indian subcontinent

Cowpea is a widely grown crop in different parts of the world, including Oman which is located in South East Arabia. Since this part of the world has long been a trade centre connecting the Arabian Peninsula with the Indian Subcontinent and South East Africa, little is known about the diversity of cowpea accessions in this area. A study was conducted to characterize and evaluate 25 cowpea accessions collected from six geographical areas (six populations) in Oman using morphological and amplified fragment length polymorphism (AFLP) analyses. The mean standardized Shannon-Weaver diversity index (H`) was found to be 0.65 for quantitative and 0.55 for qualitative traits, indicating the presence of variation in morphological traits among accessions. AFLP analysis indicated the presence of moderate levels of genetic diversity (0.214-0.316) within the 25 cowpea accessions, while the level of genetic diversity was relatively higher (0.355-0.385) within populations from the six regions, indicating the presence of variation among accessions from the same region. Analysis of molecular variance (AMOVA) indicated the presence of a very low level of genetic differentiation (F _ST = 0.032) among Omani accessions. Morphological and molecular data imply that cowpea has been grown in Oman for a relatively long period of time. Variation in the cowpea germplasm in Oman indicates that some accessions may carry important traits worth of investigation in future breeding programs.