UCR researchers develop genetic map for cowpea, accelerating development of new varieties

October 13, 2009

RIVERSIDE, Calif. - Cowpea, a protein-rich legume crop, is immensely important in many parts of the world, particularly drought-prone regions of Africa and Asia, where it plays a central role in the diet and economy of hundreds of millions of people.

Cowpea provides food that complements starchy staple crops such as corn, cassava, sorghum and millets to offer a well-rounded diet, much as beans and other grain legumes complement maize- and rice-based diets in Latin America and other places. Due to its hardy nature, cowpea plays a key role in sustaining food security for both people and their livestock.

But breeding new cowpea varieties with desirable traits, such as disease resistance, pest resistance and drought tolerance, is a time-consuming and laborious process that can take a decade from concept to release.

A challenge facing cowpea breeders, therefore, is how to accelerate the production of new and improved cowpea varieties in order to both meet the needs of a growing world population and provide the productivity gains needed by farmers to improve their economic standing.

Now a team of scientists at the University of California, Riverside has responded to this challenge by developing a high-density "consensus genetic map" of cowpea that accelerates conventional breeding severalfold and facilitates the production of new varieties of not only cowpea but also other legumes, particularly soybean and common bean (near relatives of cowpea).

To build the map, the scientists first modified and then applied advanced genetic tools developed from human genome investigations that only recently have been applied to a few major crop plants.

"The consensus map is a consolidation of six individual genetic maps of cowpea, and is far more representative of the cowpea genome than earlier maps," said team leader, Timothy Close, a professor of genetics in the Department of Botany and Plant Sciences. "We now have a reliable, powerful tool that marks a paradigm shift in crop-breeding technology."

Study results appear Oct. 13 in the online early edition of the Proceedings of the National Academy of Sciences.

The consensus genetic map of cowpea is a dense and detailed roadmap of its genome (a genome is a complete genetic blueprint). The map has approximately 1000 molecular markers throughout the genome. The markers, which are like signposts directing a motorist to a destination, are associated with traits desired for breeding and used to more deliberately design and assemble new superior varieties.

"All you need is a marker near a gene of interest," explained team member Philip Roberts, a professor in the Department of Nematology, who currently leads UCR's Bean/Cowpea and Dry Grain Pulses Collaborative Research Support Program -- a highly successful project, supported by the U.S. Agency for International Development, that has assisted African institutes in developing improved cowpea varieties. "With a marker-based map we can look into any trait desired in cowpea. The resolution of the map is such that we can accurately locate the position of genes that are contributing in a major way to various traits we'd like to see built into new cowpea varieties."

Close explained that cowpea is closely related to soybean at the genome level, allowing for the kind of cross referencing that would have been unfeasible without the consensus genetic map.

"A good number of genes are conserved across species," he said. "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 result is a tremendous acceleration in marker development to support the breeding process."

Cowpea, which originated in Africa, also is commonly referred to as southern pea, blackeye pea, crowder pea, lubia, niebe, coupe or frijole. In the United States, cowpea is popular in the south, where it is known as black-eyed peas and other names. California primarily grows the blackeyed cowpea type.

"It took us nearly ten years to breed 'California Blackeye No. 50,' our newest blackeye cowpea variety for California growers, using conventional breeding methods," said Jeff Ehlers, a specialist in the Department of Botany and Plant Sciences with more than 20 years of experience conducting genetic research on cowpea in California and Africa. "With the new technologies and map information now at hand this could have been done in half this time. The new consensus map will greatly expand our ability to locate valuable genes and incorporate them into new varieties."
-end-
UCR is host to a collection of more than 5,000 cowpea varieties from around the world. These genetically diverse varieties offer a treasure-trove of genes of potential value to breeders seeking to build better cowpea varieties.

UCR researchers have been providing assistance to African scientists for several decades. In the late 1970s, Anthony Hall, a professor emeritus of crop physiology in the Department of Botany and Plant Sciences, pioneered research on cowpea at UCR. His research on cowpea physiology contributed to a deeper understanding of the legume's adaptation to drought, heat and poor soils, and his efforts with several African breeders helped develop highly successful varieties in Senegal, Sudan and Ghana. He also led the effort to establish a genetic map for cowpea, published in 1997.

Close, Roberts and Ehlers were joined in the research by UCR's Wellington Muchero, the first author of the research paper, and Ndeye Diop, both of whom are postdoctoral researchers and hail from Africa, as well as Prasanna Bhat, Raymond Fenton, Steve Wanamaker, and Marti Pottorff. Other coauthors on the research paper are Sarah Hearne and Christian Fatokun of the International Institute of Tropical Agriculture, Nigeria, and Ndiaga Cisse of the Senegalese Institute of Agricultural Research.

The two-year research effort was funded by the Generation Challenge Program (GCP) through a grant to the GCP from the Bill and Melinda Gates Foundation, and from the U.S. Agency for International Development-funded Collaborative Research Support Program.

The University of California, Riverside (www.ucr.edu) is a doctoral research university, a living laboratory for groundbreaking exploration of issues critical to Inland Southern California, the state and communities around the world. Reflecting California's diverse culture, UCR's enrollment of about 18,000 is expected to grow to 21,000 students by 2020. The campus is planning a medical school and has reached the heart of the Coachella Valley by way of the UCR Palm Desert Graduate Center. The campus has an annual statewide economic impact of more than $1 billion.

A broadcast studio with fiber cable to the AT&T Hollywood hub is available for live or taped interviews. To learn more, call (951) UCR-NEWS.


University of California - Riverside

Related Genome Articles from Brightsurf:

Genome evolution goes digital
Dr. Alan Herbert from InsideOutBio describes ground-breaking research in a paper published online by Royal Society Open Science.

Breakthrough in genome visualization
Kadir Dede and Dr. Enno Ohlebusch at Ulm University in Germany have devised a method for constructing pan-genome subgraphs at different granularities without having to wait hours and days on end for the software to process the entire genome.

Sturgeon genome sequenced
Sturgeons lived on earth already 300 million years ago and yet their external appearance seems to have undergone very little change.

A sea monster's genome
The giant squid is an elusive giant, but its secrets are about to be revealed.

Deciphering the walnut genome
New research could provide a major boost to the state's growing $1.6 billion walnut industry by making it easier to breed walnut trees better equipped to combat the soil-borne pathogens that now plague many of California's 4,800 growers.

Illuminating the genome
Development of a new molecular visualisation method, RNA-guided endonuclease -- in situ labelling (RGEN-ISL) for the CRISPR/Cas9-mediated labelling of genomic sequences in nuclei and chromosomes.

A genome under influence
References form the basis of our comprehension of the world: they enable us to measure the height of our children or the efficiency of a drug.

How a virus destabilizes the genome
New insights into how Kaposi's sarcoma-associated herpesvirus (KSHV) induces genome instability and promotes cell proliferation could lead to the development of novel antiviral therapies for KSHV-associated cancers, according to a study published Sept.

Better genome editing
Reich Group researchers develop a more efficient and precise method of in-cell genome editing.

Unlocking the genome
A team led by Prof. Stein Aerts (VIB-KU Leuven) uncovers how access to relevant DNA regions is orchestrated in epithelial cells.

Read More: Genome News and Genome Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.