New Pinto Bean Resists Viral Diseases

"Quincy," a hardy new pinto bean, could give growers and breeders added insurance against attack by the bean common mosaic virus (BCMV).

The cultivar harbors two genes, I and bc-22, that confer resistance to all known strains of BCMV—plus bean common mosaic necrosis virus (BCMNV)—reports Phil Miklas. The Agricultural Research Service (ARS) plant geneticist is handling seed requests at the ARS Vegetable and Forage Crops Production Research Unit, Prosser, Wash. Foundation seed for growers is available from the Washington State Crop Improvement Association.

In pinto and other dry beans, severe outbreaks of the two viruses can inflict seed-yield losses up to 60 percent. They threaten the $512-million annual dry bean crop in California, Colorado, Idaho, Michigan, Nebraska, North Dakota and Washington. Also at risk are $190 million worth of snap beans from Florida, Illinois, New York, Oregon, Wisconsin and other states.

Quincy is the first commercial pinto with this specific combination of genes to completely control the seedborne BCMV and BCMNV spread between plants by aphids. Insecticide spraying, clean-seed programs and sanitation are the standard controls, but genetic resistance is the keystone defense.

Miklas and colleagues developed Quincy from a cross between Othello, a popular commercial pinto cultivar, and the black bean germplasm line A-55. While Quincy resists BCMV and BCMNV and fends off curly top virus, it's susceptible to Uromyces appendiculatus, the fungus that causes bean rust disease.

In field trials, Quincy produced seed yields consistently higher than Othello and another cultivar, Burke. The tests were conducted in Washington, Colorado and other states under optimal and high-stress conditions, including soils with little residual nitrogen or moisture. Quincy's plants generally grew taller than Othello's but took four to seven days longer to mature. Quincy's seed is slightly larger than Othello's and has comparable canning properties.

Matt Silbernagel (retired, formerly ARS) and An Hang of Washington State University-Prosser collaborated with Miklas on the new pinto bean's development, testing and evaluation.

ARS is the U.S. Department of Agriculture's chief scientific research agency.