Modern Breeding of Cowpea (Vigna unguiculata L. Walp.) in sub-Saharan Africa

Cowpea (Vigna unguiculata L. Walp.) 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. It also helps enrich poor and fragile soils across these agro-ecologies. Although cowpea is more tolerant than most other crops to drought, heat and poor soil conditions, pests and diseases in these regions render heavy yield losses and are key limiting factors underlying why traditional varieties in Africa yield 3- to 5-fold lower than their potential. Collaborative breeding programs aiming to develop improved cowpea cultivars for Africa are being implemented under the ‘Tropical Legumes’ projects funded by the CGIAR Generation Challenge Program. Marker-assisted recurrent selection is one strategy being evaluated using several populations, each derived from a cross between two elite parents carrying different traits relevant to each target environment. Quantitative trait loci (QTL) have been discovered at F₃ or F₄ generations, and members of highest QTL-index families were genotyped, selected and inter-crossed to recombine favorable alleles. Marker-assisted backcrossing is being applied to accelerate introgression of known resistance gene(s) into local cultivars, including resistance to the parasitic weed Striga gesnerioides, and several fungal and bacterial diseases. These activities are enabled by community resources developed by the Integrated Breeding Platform (https://www.integratedbreeding.net/) including high-density genetic maps, out-sourced SNP genotyping, and decision support tools. The main challenges include logistical issues that delay decision-making; these are being addressed to improve breeding cycle efficiency.