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Looking for Genes To Protect Beans


  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 Kathryn Barry Stelljes, Agricultural Research Service Information Staff.


Phillip N. Miklas is in the USDA-ARS Vegetable and Forage Crop Research Unit, 24106 N. Bunn Rd., Prosser, WA 99350-9687; phone (509) 786-9258, fax (509) 786-9277.

"Looking for Genes To Protect Beans" was published in the March 2001 issue of Agricultural Research magazine.

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