Parental evaluation, polymorphic loci marker survey and allelism study of earliness in cowpea (Vigna unguiculata (L.) Walp)

Abstract

The objectives of this study were to confirm genetic variability of three early-to-medium and three extra-early maturing cowpea genotypes selected from the previous studies, identify polymorphic loci markers between the two maturity groups, and investigate the allelism among the earliness genes in the three extra-early maturing genotypes. The parental genotypes were sowed on the Striga hotspot field of the CSIR-Savana Agricultural Research Institute, in a Randomized Complete Block Design with three replications. Data were collected on the number of days to first flower appearance (DFFA), days to 50% flowering (DFF), days to 95% pod maturity (DNPM), Striga emergence, Aphids infestation, grain yield and hundred seed weight. Leaf samples were taken from individual plants, and DNA extracted and genotyped for the polymorphic marker survey. Crosses were made among the three extra-early maturing genotypes to generate F 1 populations, and hybridity test conducted. The successful ones were advanced to F 2 and evaluated for DFFA and DNPM. The results showed significant differences between the genotypes, and two main clusters were identified for pod maturity. Polymorphic loci markers between the parental pairs were identified. These markers would play a significant role in the hybridity testing and could also be used with other markers to map the earliness genes in cowpea. The study also showed that earliness gene(s) in CB27 is non-allelic to those of Tobonaa and Sanzi-Nya. CB27 could be used to introgress earliness and large seed size into improved varieties lacking these two important traits.