Assessing genetic influence and inheritance patterns of yield components in cowpea introgressed with the cry1ab gene for the control of Maruca vitrata pest

Cowpea is an important food legume widely grown and consumed across the semi-arid regions of Africa, serving as a rich source of essential nutrients, including proteins, vitamins, carbohydrates, and minerals. However, cowpea cultivation faces major challenges due to the high prevalence of insect pests that adversely impact crop yield, with the Legume pod borer (Maruca vitrata) being one of the most damaging pests, capable of causing yield losses ranging from 20% to 80%. To combat this issue, genetically engineered cowpea event 709A, which incorporates the Cry1Ab gene from Bacillus thuringiensis (Bt) for resistance against Maruca vitrata, has been developed and released in Nigeria as SAMPEA 20-T. This study aimed to determine the heritability and primary gene effects of some yield related traits in cowpea lines introgressed with the pod borer resistance gene (Cry1Ab). A randomized complete block design was employed, involving six generations (P1, P2, F1, F2, BC1, and BC2) from four crosses (Padi-tuya x PBRC, Apagbaala x PBRC, Kirkhouse x PBRC, and Wang-kae x PBRC). These crosses were derived from four M. vitrata-susceptible varieties and an elite M. vitrata-resistant line (PBRC), and were evaluated at the confined field trial (CFT) site in Nyankpala. The results indicated that most traits in the four crosses exhibited duplicate epistasis among dominant decreasers, while a few traits showed complementary epistasis among dominant decreasers. A broad range of narrow sense heritability estimates were observed, ranging from 0% to 97%. Based on the analysis of gene effects—including additive, dominance, and epistasis—it was concluded that pedigree breeding would be the most effective approach for enhancing most of these traits.