Snap bean growers nationwide could
benefit if ARS geneticist Phillip N.
Miklas succeeds at unlocking the genetic secrets of resistance to white mold
disease. Unlike dry beans, snap beans are eaten as flavorful, fleshy green
pods. They are sold fresh, frozen, or canned.
Some breeding lines already have partial resistance to white mold, the most
costly disease of snap beans in the United States. White mold lowers bean yield
and pod quality and can kill the plants. The fungus also infects many other
crops, including lettuce, soybean, alfalfa, potato, pea, canola, and sunflower.
Miklas works at the ARS Vegetable and Forage Crop Research Unit in Prosser,
Washington. He's teaming up with researchers at Novartis Seeds, Inc., of Nampa,
Idaho, under a cooperative research and development agreement. They will each
develop a separate population of beans. Both sets of beans will use a breeding
line developed at Cornell University as one of the parents. The line
demonstrates some resistance to the disease.
For the other parents, they'll use different commercial snap bean varieties
that are susceptible to white mold. One population will be used to generate the
genetic information and the other to confirm the genetics.
"By crossing a resistant and a susceptible line of beans and then
comparing the offspring, we hope to narrow down the location and number of
genes responsible for the resistance," Miklas says. Then he plans to
develop resistance-linked markers that can be used to incorporate this
resistance into commercial snap bean cultivars.
Scientists estimate that 5 to 15 percent of the world's snap bean crop is lost
to white mold. The disease costs U.S. farmers $18 million each year in lost
yields and fungicide sprays. Worldwide, the crop is worth about $300 million
annually. Because the disease lives in the soil and infects a myriad of plants,
growers have limited options for using other crop rotations to break the
fungus' life cycle.
While the resistance genes would probably apply only to beans, it is possible
that information obtained by Miklas may help researchers working with other
crops affected by the disease.By
Stelljes, Agricultural Research Service Information Staff.