Association studies of agronomic traits, genetic structure and phylogeny of some Nigerian cowpea cultivars
The genetic component of nine elite cowpea cultivars in Nigeria were analysed using single nucleotide polymorphism (SNP) technology along with their agronomic trait with the aim of understanding their genetic structure, diversity, phylogenic relationship and marker-trait association among the varieties. Twenty-five morpho-agronomic and disease reaction traits of the cultivars were studied. Genotyping was done with 255 SNPs markers, while Association analysis was done using the general and mixed linear models. 160 SNPs (71.0%) were highly polymorphic. There was narrow genetic diversity with three structured populations and three evolutionary paths identified among the cultivars. 93 SNPs (26 SNPs associated with more than one trait) and 84 SNPs (7 SNPs associated with more than one trait) were identified using the General and Mixed Linear Models respectively. Strong associated SNP markers which can be used to improve cowpea production were identified. The study also provides information that can be utilised in cowpea yield and disease resistance improvement programme.