Plant pathologist Marcial A. Pastor-Corrales of the ARS Vegetable Laboratory at Beltsville, Md., worked with his colleagues to breed BelMiNeb-RMR-8, -9, -10, -11, -12 and -13. The germplasm lines are resistant to all known strains of the rust pathogen Uromyces appendiculatus. What's more, they have two additional genes that protect them against all strains of two other organisms--bean common mosaic virus and bean common mosaic necrosis virus.

The Great Northern bean is the fourth most important bean class in the United States. These large, white beans are popular in baked bean dishes as well as in soups.

To breed the resistant lines, the scientists used gene pyramiding, in which more than one desirable gene is added to the plant. In this case, four genes that are resistant to rust and two genes that are resistant to the viruses were added through conventional breeding with molecular marker assisted selection. There are many strains of the pathogens that cause the rust and viral diseases. These strains may vary from one location and year to another. By placing four rust and two mosaic resistance genes in the BelMiNeb beans, there is a better chance that the bean will stay resistant to the rust and to the two viral diseases.

Rust has severely reduced various dry bean yields during the past few decades, and in some years has damaged half of the crop in certain locations. Since the BelMiNeb beans are naturally resistant to rust and several viruses, farmers will not have to use chemicals on the beans to control these diseases.

A limited quantity of seed is available by emailing Pastor-Corrales at pastorm@ba.ars.usda.gov.

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

Note: If no author is given, the source is cited instead.

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