Michigan Ag Connection - USAID-Funded Research in West Africa Benefits U.S. Bean Growers

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USAID-Funded Research in West Africa Benefits U.S. Bean Growers
Michigan Ag Connection - 10/26/2021

The U.S. Agency for International Development (USAID) funds innovative projects for results driven outcomes designed to promote self-reliance and resilience among developing countries. However, one USAID funded project has in turn, brought innovation developed in West Africa back to the U.S. for the benefit of American cowpea farmers.

The newly developed California Blackeye 77 (CB77) black-eyed pea cultivar provides natural resistance to aphids through breeding of traits identified in African cowpea germplasm through research funded by USAID in West Africa. The project is led by Dr. Philip Roberts at the University of California -- Riverside (UCR) in collaboration with the Council for Scientific and Industrial Research -- Savanna Agricultural Research Institute (CSIR-SARI), Ghana; the L'Institut de l'Environnement et des Recherches Agricole (INERA), Burkina Faso; and the L'Institut Se?ne?galais de Recherches Agricoles (ISRA), Senegal.

The project is managed by Michigan State University through decades of USAID legume research investments through the Dry Grain Pulses Collaborate Research Support Program (CRSP) (1980-06), the Pulse CRSP (2007-12), the Feed the Future Innovation Lab for Collaborative Research in Grain Legumes (2012-17), and the current Feed the Future Innovation Lab for Legume Systems Research.

According the California Dry Bean Growers Association, black-eyed peas were introduced in 1941 and are grown in California's Central and Southern San Joaquin Valley and Sacramento Valley. They are also a popular crop in many southern U.S. states. Black-eyed peas originated in Africa where they are commonly known as cowpea (Vigna unguiculata L. Walp), and where their grain has a range of seed-coat colors and patterns. For thousands of smallholder African farmers cowpea is an important food crop and offers an inexpensive protein source which complements cereals for a complete diet.

Whether grown in Africa or in the U.S., cowpea aphid (Aphis craccivora Koch) is a destructive insect pest of black-eyed peas. They spread quickly and affect cowpea plant health in many ways. Aphids transmit mosaic virus disease which affects yield. They also cause black mold growth by transferring honeydew, a sweet sticky substance that can be a breeding ground for mold. The insects are difficult to control as their natural enemies often appear after infestation has occurred.

Using marker-assisted backcrossing (MABC) Dr. Roberts and his team were successful in breeding two known quantitative trait loci (QTL) for aphid resistance from an African cowpea breeding line. QTL are sections of the genome, all genetic material of the plant including DNA, that are associated with a quantitative trait. In this case, aphid resistance was the desired quantitative trait.

MABC is a breeding technique that allows for only the desired QTL from a donor plant to be incorporated into a popular local cultivar, known as the recurrent parent. This transfer of genetic material provides the local cultivar with the enhanced, desired trait while maintaining all other genetic characteristics. The outcome is that the new cultivar is essentially the same as the local cultivar, but with value added through the new trait addition of aphid resistance.

The result of this MABC breeding is CB77, a blackeye-type cowpea distinguished by its ability to resist aphid infestation. The industry standard cultivar, California Blackeye 46 (CB46) was used as the recurrent parent of CB77. Aphid damage to CB77 has been shown in research trials to have 0-10% aphid plant coverage compared to 60-70% aphid plant coverage in the parent CB46. CB77 also includes similar favorable yield and seed quality traits as the parent line CB46 offering farmers an elite black-eyed pea variety.

"With MABC it took about eight years from initial crosses to the release of CB77, whereas conventional breeding can take up to 10 to 15 years to develop a cultivar. This means considerable cost and time savings", said Dr. Bao-Lam Huynh, UCR plant breeder who manipulated the trait and got it incorporated into the useful cultivar CB46.

This new cultivar CB77 offers U.S. growers integrated pest management alternatives including the reduction of synthetic chemical pesticides. Such pesticides can be costly, and could be harmful to human health if mishandled or misused. Environmental impacts are also a factor as some of these chemicals can also harm beneficial insects.

Read more about the research, which was also supported by the California Dry Bean Advisory Board, in the newly published article, "Registration of aphid-resistant 'California Blackeye 77' cowpea" in the Journal of Plant Registrations.

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