Genomic Resources Applied to Marker-Assisted Breeding in Cowpea

Cowpea (Vigna unguiculata L.) is an important protein-rich grain legume and fodder crop grown across the semi-arid zones of the tropics below the Saharan desert and similar agro-ecological zones of eastern and southern Africa and the world. Drought, heat, low fertility soils, pests and diseases are key factors causing traditional varieties in Africa to yield much lower than their potential. Collaborative breeding programs are being aimed to develop improved cowpea cultivars for Africa. Marker-assisted backcrossing is being applied to accelerate introgression of known resistance genes into local cultivars, including resistance to the parasitic weed Striga, several fungal and bacterial diseases, nematodes and insect pests. Marker-assisted recurrent selection (MARS) is being evaluated in four countries in Africa using four populations, each derived from a cross between elite parents carrying traits relevant to each target environment. Following QTL discovery at F₃ - F₄ generations, members of the highest QTL-index families were genotyped, selected and inter-crossed to recombine favorable alleles. These modern breeding activities are enabled by the application of cowpea genomic resources including genetic maps, trait-linked markers, out-sourced SNP genotyping platform, and the decision support tools of the Generation Challenge Programme – Integrated Breeding Platform.