2017 ASHS Annual Conference

Cowpea (Vigna unguiculata L. Walp., 2n=22), an annual herbaceous legume plant, is widely grown in tropical and subtropical regions of the world. Genetic diversity study will provide the base of utilization of cowpea germplasm in breeding. Both genetic and phenotypic diversities were analyzed in 768 cowpea genotypes, originally collected from 56 countries. A total of 17 phenotypic traits were used for phenotypic diversity and 1028 SNPs used for genetic diversity studies. Genetic analysis was conducted based on cowpea genotype individually and also based on genotype grouped by nine geographic regions: South Africa, West Africa, Central East Africa, East Asia, Central West Asia, Europe, Oceania, North America, and Latin America plus two specific groups: ‘India’, the germplasm accessions from India and ‘America Cultivar’, the cultivars from USA. The Shannon-Weaver diversity index (H’) and Simpson index (1-D) were calculated for the qualitative and quantitative characters to compare diversity between the different characters and among various regions and the Canonical discriminant analysis was also used for eleven quantitative traits. Results indicated that the geography grouped affected both phenotypic and genotypic variations but the dendrograms didn't fully match between the phenotypic and genotypic data. However, both data supported that the African was the original domestication place in this study; the accessions from Asia had higher diversity and closer to the cultivated cowpea; the most agricultural diversities were observed in the India population, which were close to the population from Central East Africa; and the USA breeding sources were closer to West Africa and East Asia. This study will provide cowpea breeders with how to use cowpea germplasm in breeding programs.