Dry Bean Research
November 23, 2005
Geneticists Phil Miklas (left) and George Vandemark analyze computerized reaearch used to rapidly genotype bean plants for a virus-resistance gene.
A new germplasm line dubbed "USDK-CBB-15" is now available for breeding new varieties of dark red kidney beans that can resist common bacterial blight.
Caused by the pathogen Xanthomonas axonopodis pv. phaseoli, bacterial blight is an endemic disease that can affect bean crops mostly east of the U.S. Continental Divide. Antibiotic treatment, clean-seed programs and sanitation are standard control measures. However, resistant crops are the key defense, according to Phil Miklas, a plant geneticist in the USDA Agricultural Research Service's Vegetable and Forage Crops Production Research Unit in Prosser, Wash.
In susceptible bean plants, the disease symptoms include large brown blotches with lemon-yellow borders on leaf surfaces and small, discolored seed in infected pods. Severe outbreaks can cause yield losses of up to 40% in susceptible crops.
Miklas developed USDK-CBB-15 using marker-assisted selection, a method of detecting inherited genes that speeds the screening of plants for desired traits such as disease resistance. USDK-CBB-15 is the product of kidney bean crosses that Miklas made to incorporate resistance genes from the Great Northern bean cultivar "Montana Number 5" and the breeding germplasm line XAN 159.
James Smith, in ARS' Crop Genetics and Products Research Unit at Stoneville, Miss., and Shree Singh, with the University of Idaho at Kimberly, collaborated with Miklas on the new kidney bean's development, testing and evaluation.
"Obviously, this is a very good development. While Montcalm Dark Red Kidney has had resistance to common bacterial blight (one of the reasons why it was so popular among the growers), developing germplasm with other sources of resistance broadens the genetic base of those market classes," says Ken Grafton, who before becoming Dean of Agriculture at North Dakota State University, and director of the N.D. Agricultural Experiment Station, was NDSU's dry bean breeder.
Grafton says kidney beans (other than Montcalm) generally are very sensitive to common bacterial blight, so this new germplasm line should have a significant impact on materials developed using this line as a parent. He says breeders should be able to utilize this resistance in kidney and cranberry bean breeding programs.
The United States is the sixth-leading producer of edible dry beans, generating farm sales of $451 million in 2001-03, according to the USDA's Economic Research Service. Per-capita consumption of edible dry beans is 6.8 pounds, according to ERS, with kidney beans finding favor in soups, salads, chili and other dishes. Beans are also an excellent source of antioxidants, fiber, protein, and vitamins for healthy diets, Miklas notes.