a report on this research in Agricultural Research magazine.
U.S. Potatoes Could Get Disease
Resistance from Their Mexican Cousins
By Linda McGraw
September 1, 2000
The great American spud has a wild Mexican cousin with genes to help U.S.
farmers cut their use of fungicides to combat late blight, the disease that
caused the Irish potato famine. Agricultural
Research Service researchers in Madison, Wis., have developed new ways to
incorporate late blight resistance into U.S. potatoes from Solanum
pinnatisectum, a wild species found in central Mexico.
Late blight, caused by the fungus Phytophthora infestans, costs
potato growers about $3 billion annually worldwide, according to the
International Potato Center (CIP) in
Lima, Peru. In the United States, using fungicides to control late blight has
driven potato production costs up to nearly $200 an acre in some
Using a technique known as embryo rescue, the researchers mated S.
pinnatisectum with a derivative of a commercial U.S. potato. Embryo rescue
involves removing the normally developing embryo from the failing, developing
seed and placing it on a culture media that will sustain its growth. A hybrid
from the rescue can be used by breeders as a maternal parent in a mating with
Until now, these wild Mexican species have been difficult to cross with most
other cultivated or wild species. But its worth doing because the wild
species have genetic resistance to viruses, insects, fungi and nematodes.
Another plus: This Mexican species resists early blight, which produces
problems similar to late blight. Early blight is caused by the fungus
Alternaria solani. In 1994, the annual cost for controlling early blight
alone was estimated to be $21 to $44 million in the United States and Canada.
Resistance to both blights is important to reduce reliance on fungicides. In
trials, the hybrid also resisted the Colorado potato beetle.
S. pinnatisectum is maintained at the
Genebank in Sturgeon Bay, Wisconsin.
A report on this research appears in the September issue of Agricultural Research magazine.
The potato genetics work is part of a nationwide effort in
research at ARS, the USDA's chief
scientific agency. For more information, see the list of ARS national programs
in "Crop Production, Product Value, and Safety" at:
Scientific contact: Robert E. Hanneman, Jr., ARS
Vegetable Crops Research,
Madison, Wis., (608) 262-1399, fax (608) 262-4743,