Genetic improvement of drought tolerance in cowpea (Vigna unguiculata): Integrating physiology, genomics, and breeding

Abstract

Cowpea (Vigna unguiculata (L.) Walp.) is a critical grain legume for dryland agriculture, yet drought remains the major constraint to stable productivity. This review synthesizes recent progress in deciphering drought adaptation in cowpea, integrating advances in physiological trait dissection, managed stress screening, breeding strategies, and genomics-enabled improvement. We highlight how high-quality reference and pan-genomes, QTL mapping, genome-wide association studies, and genomic selection have revealed the highly polygenic and stage-dependent nature of drought tolerance, with key roles for phenology, root architecture, stomatal regulation, photosynthetic resilience, and yield stability. Emerging multi-omics and functional validation studies are uncovering regulatory networks centered on ABA signaling, redox control, and osmotic adjustment, providing candidate genes and biomarkers for precision breeding. We discuss current limitations and outline future directions to translate molecular insights into climate-resilient, farmer-preferred cowpea cultivars.