RIVERSIDE, Calif. Cowpea is a protein-rich legume crop that plays a key role in sustaining food security for people and their livestock. Immensely important in many parts of the world, particularly drought-prone regions, it plays a central role in the diet and economy of hundreds of millions of people in Africa and Asia.
To meet the needs of a growing world population, new cowpea varieties with desirable traits, such as higher yield and quality, disease resistance, pest resistance and drought tolerance, are needed. But breeding these new varieties the conventional way crossing one variety with another, based on best guesses is time-consuming and laborious.
Enter DNA marker-assisted breeding, a genetic tool that can greatly accelerate breeding efforts by utilizing genetic "markers" or molecular flags in the plant genome that indicate the location of a particular genetic trait. Breeders use the markers to screen large populations of plants from crosses of different varieties. In effect, the markers help breeders locate genes linked to traits the way road signs help a motorist arrive at a destination.
This month, scientists at the University of California, Riverside received substantial funding by way of two grants from the U.S. Agency for International Development (USAID) to continue their work on developing better yielding varieties of cowpea through new genomic resources and marker-assisted breeding research by which UC Riverside directly impacts cowpea production in several countries in Africa. The grants support USAID's agricultural research and capacity building work under Feed the Future, the U.S. Government's global hunger and food security initiative.
The two grants total nearly $7 million. The first, creating the Feed the Future Innovation Lab for Climate-Resilient Cowpea, is a nearly $5 million grant that supports a new five-year cowpea-breeding project with partners in four West African nations: Burkina Faso, Ghana, Nigeria and Senegal. The second grant, titled "Genetic improvement of cowpea to overcome biotic stress and drought constraints," extends a ten-year project and brings additional funding of about $2 million over four-and-a-half years to UCR through the Feed the Future Innovation Lab for Collaborative Research on Grain Legumes as a sub-contract with Michigan State University, East Lansing.
Specific traits of interest for cowpea improvement will include resistance to the drought-associated fungal pathogen Macrophomina phaseolina, tolerance against drought-induced early senescence, and resistance to insects, nematodes and other diseases, along with high yield and maintenance of traits of especial interest to Africa such as seed size, seed coat color and patterns.
"UCR cowpea research goes back more than 30 years," said Timothy Close, a professor of genetics in the Department of Botany and Plant Sciences and the principal investigator of the $5 million grant. "The USAID funding through Feed the Future is recognition of the tremendous value that UCR brings to cowpea research and the positive impact it is having on cowpea breeding for African farmers."
Cowpea originated in Africa. It is known also 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 blackeyed peas and other names. California primarily grows the blackeyed dry-grain cowpea type.
"Both research projects are intimately tied to our collaborators in sub-Saharan Africa," Close said. "Beyond the technical capability we offer, we have a good network of partners in Africa for on-the-ground application of genetic improvement for cowpea."
Close explained that to breed improved varieties of cowpea, scientists must understand its genetic makeup, mark the location of genes that control important traits, and select the best trait combinations they wish to see emerge in new varieties. Close also explained that with very dense genetic markers it is not crucial to understand exactly which genes underpin the traits, though such information can be helpful for purposes such as finding similar genes within collections of genetically diverse relatives of cultivated cowpeas or even in other plants.
Rather than genetically modify cowpea via manipulation of genes in test tubes, the researchers will use the marker-assisted breeding technology to expedite conventional breeding and, thereby, speed up the production of new and improved cowpea varieties. Associated with traits desired for breeding, the genetic marker profiles of progeny derived from carefully chosen parents will be used to more deliberately design and assemble new superior cowpea varieties.
"We are no longer confined to slower, less directed methods of plant breeding, nor must we base all hope on genetically modified organisms," Close said. "With marker-assisted breeding we can, over just a few years, accomplish improvement in cowpea varieties that can enormously benefit farmers, markets and consumers."
Philip Roberts, a professor of nematology and the principal investigator on the $2 million USAID grant, explained that the marker-assisted breeding technology for cowpea, developed at UCR, is based on finding genetic variability in cowpea that already exists in nature and that can then be brought into breeding programs.
"Our method is focused on finding genetic variability that nature has already created and marking where the genes for the favorable traits are located in the cowpea genome," he said. "The marker-assisted selection then allows for the crossing of varieties with complementary sets of favorable traits so that these traits can be stacked up and passed down to progeny. It's not about making transgenes and inserting them into plants. It's about bringing favorable traits from donors into highly bred cultivars via accelerated cross-breeding."
Close and Roberts will be joined in the analysis by Stefano Lonardi, a professor of computer science and engineering and a co-principal investigator on the team, who will help process large amounts of data that the research projects will generate.
"We will use a computational method that greatly reduces the possibility of making mistakes and also reduces the cost," Lonardi said. "This method makes it possible to mark where in the genome the genes are located that influence, say, drought-tolerance. And the method also identifies those progeny that carry the alleles, which are forms of genes, for this and other desirable traits."
Close explained that marker-assisted breeding can also be understood as being analogous to creating a painting.
"Imagine you have eight different sources of favorable alleles," he said. "You can make a painting by having a blue segment in one section of the canvass for drought adaptation, a yellow one in another section for aphid resistance, and so on. This way, you create what's called a genetic ideotype. You then use markers to cross one variety with another, and calculate how close each progeny is to the ideotype. The goal is to get a variety close to the genetic ideotype through the least number of steps. Because the marker system has good knowledge-based efficiency built into it, it can deliver a cowpea variety that is close to the ideotype in as little as four to five years."
UCR has already had much success in releasing new cowpea varieties in California and West Africa, and has a longterm blackeye breeding program funded by the California Dry Bean Advisory Board.
"The UCR Coachella Valley Agricultural Research Station closely resembles environmental conditions in West Africa," Roberts said. "The lessons learned here in breeding this legacy crop plant have already helped boost yield and consumer adoption in Africa."
UCR is host to a collection of more than 5,000 cowpea accessions from around the world. Researchers at the university, like, most recently, Close and Roberts, 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; 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.
"The UCR cowpea team has trained many graduate students from Africa at UCR over the years," Close said. "Several of these young and bright scientists have returned to their countries of origin and applied in farms there the knowledge in cowpea genetic research they gained at UCR. As before, in both the Feed the Future projects we will emphasize direct training of African breeders to ensure effective adoption of best practices related to the use of genetic markers."
The research projects will support a number of UCR graduate students, postdoctoral researchers, support staff and visiting scientists in the labs of Close, Roberts and Lonardi.
|Contact: Iqbal Pittalwala|
University of California - Riverside