Development and Characterization of a Mini-Core Collection of Cowpea.

Incorporation of new sources of genetic diversity into breeding programs is crucial for continuing to increase crop yields and for responding to climate-related stresses. Germplasm collections provide a source of genetic and phenotypic diversity, but characterization of these resources is required to increase their utility for breeding programs. Cowpea (Vigna unguiculata L. Walp.), native to Africa, is one of the most important crops for subsistence farmers in sub-Saharan Africa. It is also widely grown in Latin America, parts of Asia, Southern Europe, and the Southern United States. Diverse cowpea germplasm is available from several germplasm collections including one at the University of California, Riverside, which contains about 6,000 entries. Based on previous genetic and phenotypic knowledge, we have assembled a mini-core collection of 384 accessions from ~60 countries on six continents which represents worldwide diversity of cultivated cowpea. This mini-core collection has been genotyped with the “Cowpea iSelect Consortium Array” containing 51,128 SNPs. Principal component and genetic assignment analyses are being used to examine the genetic relationships between accessions and to identify genetic structure within the population. Several morphological and agronomic traits, including leaf shape, flower color, days to flowering, and 100-seed weight are being measured in the mini-core collection and will be subject to GWAS.