Accessing the Genome of Cowpea to Provide Climate Resilient Crops for Food Security

Cowpea (Vigna unguiculata L. Walp.) is an important grain legume and fodder crop grown across semi-arid and dry savannah zones of the tropics in sub-Saharan Africa and similar agro-ecological zones worldwide. It also helps to build typically poor and fragile soils that predominate across much of these agro-ecologies. Cowpea is more tolerant than most other legume and non-legume crops to drought, heat and poor soil conditions. Cowpea holds considerable genetic variation for these traits, affording the opportunity to breed for enhanced drought and heat tolerance, and to be a resource for these traits to other less tolerant crop species such as soybean and common bean. We have applied new genomic resources to identify regions of the genome housing QTL controlling drought tolerance and heat tolerance. Key resources include individual and consensus genetic maps, EST-derived mapped-SNP genotyping platforms, BAC libraries, a physical map anchored to the genetic map, and a partial whole genome sequence. Coupled with multi-location phenotyping data sets from African and US field sites, numerous QTL identified for seedling stage and mid- to late-season drought and heat tolerance have been positioned on the genetic map. BAC clones with flanking marker tags in the QTL regions have been identified, and sequence comparisons with soybean and common bean whole genome sequences revealed candidate genes for several trait determinants. These marker-tagged sites housing gene candidates for abiotic stress tolerance provide targets for marker-assisted breeding in cowpea and for gene cloning approaches to utilize knowledge from cowpea to improve other crops.