Transgenic Cowpea Expressing Synthetic BtCry1Ab Confers High Resistance to Legume Pod Borer (Maruca vitrata)

Cowpea, an important food legume crop, suffers significant yield losses due to insect pests, particularly the legume pod borer (Maruca vitrata). Narrow genetic base and lack of sufficient resistance to M. vitrata in existing cowpea germplasm, make them less effective in managing M. vitrata populations. To address this challenge, a transgenic approach is explored. In this study, we develop transgenic cowpea with enhanced resistance to M. vitrata by overexpressing a synthetic cry1Ab gene, driven by constitutive CaMV35S viral promoter, in an Indian cowpea cultivar. High expression of Cry1Ab was detected in leaves and pods. Bioassays with M. vitrata and Helicoverpa armigera larvae demonstrated significant resistance of transgenic lines to these lepidopteran pests. The transgenic lines exhibited reduced pod damage, decreased larval feeding, and increased insect mortality compared to non-transgenic controls. NMR analysis demonstrated absence of any new metabolites in transgenic plants. Furthermore, these transgenic lines showed no penalty on growth and development. The transgenic lines exhibited no observable phenotypic drawbacks, indicating their promise for sustainable agricultural practices. Our findings suggest that these transgenic cowpea lines could offer broad-spectrum protection against these pests, providing an effective pest management solution.