Scientists Develop Cowpea Genetic Map

A team of researchers led by scientists at the University of California Riverside (UCR) said they have developed a high-density consensus linkage map for cowpea (Vigna unguiculata), a protein-rich legume crop that plays a central role in the diet and economy of hundreds of millions of people. Due to its hardy nature, cowpea plays a key role in sustaining food security in drought prone regions of Asia and Latin America, and particularly in Sub-Saharan Africa. Despite its importance, cowpea is considered an orphan crop with limited genomic references.

The researchers integrated sequence data on more than 183,000 expressed sequence tags (ESTs) identifying thousands of possible markers. SNP mining from these ESTs yielded about 10,000 high-confidence SNPs from which an Illumina GoldenGate genotyping array was developed. The researchers then applied the array to 741 recombinant inbred lines from six mapping populations and they found that about 90 percent of the SNPs appeared to be dependable cowpea genetic markers. About 900 of these markers were integrated into a consensus genetic linkage map. The resulting map spans 680 cM with 11 linkage groups and an average marker distance of 0.73 cM.

The researchers found that cowpea is closely related to soybean at the genome level. "A good number of genes are conserved across species," said Philip Roberts, a researchers at UCR. "By looking at a marker on a cowpea chromosome, we can cross reference it to information on, say, the soybean genome, based on the DNA sequences of the marker. This facilitates knowledge transfer between these species, so advances made in cowpea can be translated into valuable information for soybean, and vice versa."

The original story is available at http://www.universityofcalifornia.edu/news/index.php The open access paper published by PNAS is available at http://dx.doi.org/10.1073/pnas.0905886106