Genetic diversity and population structure of cowpea of Côte d’Ivoire [Vigna unguiculata (L.) Walp.] using agronomic and SNP markers

The intra and inter-accessions diversity of Cowpea consumed in Côte d’Ivoire were surveyed in this study. A significant pool of cowpea landraces is available, but the lack of detailed information on their diversity and agronomic potential makes it difficult to develop breeding programmes. The specific of this study is to characterize the cowpea collection and to highlight the phylogenetic relationship between the accessions. A total of 111 accessions initially divided into 12 phenotypes according to seed colours: red, cream, brown-orange, white, brown red, brown olive and brown argil were assessed based on 18 agromorphological traits. Morphological analysis revealed a significant variation for all 18 traits studied. Principal Components Analysis (PCA) highlighted that 56.139% of the overall phenotypic variation is attributed to number of nodes, days to initial flowering, number of ovules, number of seeds, seed length per pod, seed weight and hundred-seed weight. The accessions were divided into two main groups. Group 1 was characterised by late flowering, high seed weight and abundant foliage. Group 2 was made up of early flowering accessions. The phylogenetic tree, based on Ward’s minimum variance method of 15 SNPs also revealed two genetic groups. Additionally, AMOVA indicated higher genetic diversity within morphotypes (95%) than between morphotypes (5%). The Morphological and SNP markers used in this study showed that cowpea accessions of Côte d’Ivoire are divided in two genetics groups.