A new potato with resistance to the world’s worst potato disease is now available to plant breeders.

“This potato is highly resistant to attack by late blight, the disease that caused the Irish potato famine of the 1840s," said plant pathologist Dennis L. Corsini with the Agricultural Research Service in Aberdeen, Idaho. He and colleagues at Aberdeen and at Prosser, Wash., developed the new spud, known as AWN86514-2. The Agricultural Research Service is the chief research agency of the U.S. Department of Agriculture.

Commercial varieties bred from the new potato are at least six years away, Corsini cautions.

Late blight is caused by a fungus called Phytophthora infestans. New, more aggressive strains that are fungicide-resistant have appeared in recent years, so breeders have been scrambling to find potatoes with natural resistance.

"The new potato held up well when attacked by the newest and most virulent strains of the fungus,” Corsini said. “It was far more resistant than any of the commercial potato varieties now in production in the United States."

Corsini and ARS geneticist Joseph J. Pavek at Aberdeen coordinated field experiments by ARS and other scientists in eight states and a heavily blight-infested region of Mexico.

Corsini and Pavek are making laboratory-produced plantlets, and small tubers suitable for planting, available to breeders. They hope AWN86514-2 can be bred with top-rated experimental potatoes or commercially successful varieties to boost their disease resistance. Then, farmers could eventually have new, blight-resistant commercial varieties. But breeding and testing could take six to 10 years or more.

Tests by Corsini have shown that AWN86514-2 also resists viruses that cause two other potato diseases, potato virus Y and potato leafroll virus. The new potato's parents are a french-fry variety--Ranger Russet, developed by Pavek--and a potato selected from Poland's potato breeding institute.

ARS released the new potato in collaboration with the agricultural experiment stations of Oregon, Idaho and Washington.

Potatoes--whether baked or processed into chips, fries, potato flakes or other products--are the nation's favorite vegetable. The average American eats about 143 pounds of potatoes a year.

An article about AWN86514-2 will appear early next year in the American Journal of Potato Research.

Scientific contact: Dennis L. Corsini, ARS Small Grains and Potato Research Unit, Aberdeen, Idaho, phone (208) 397-4181, fax (208) 397-4311, dcorsini@uidaho.edu .

By Marcia Wood

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