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Dr. Belknap in greenhouse

New Gene May Simplify Breeding of Superior Spuds

By Marcia Wood
December 24, 1997

Tomorrow's potatoes may boast a wider array of prized traits like disease and insect resistance, borrowed from their wild relatives. That's because new genetic engineering research by scientists with the Agricultural Research Service should make it easier for breeders to sidestep a problem that often frustrates their use of primitive potatoes.

The wild spuds, native to the Andes Mountains in South America, are a crucial source of genes useful for developing new commercial varieties with traits valuable to potato growers or processors. But sometimes those wild potatoes contain high levels of unwanted, bitter compounds called glycoalkaloids. So, when breeders cross a wild potato with a commercial variety, they have to discard any offspring with a high glycoalkaloid level. The high-glycoalkaloid offspring are useless--no matter what valuable traits they also possess.

This problem could vanish in the future. ARS scientists recently discovered a gene that, when re-worked, undermines production of an enzyme without which potatoes can't make a key glycoalkaloid. The thwarted enzyme is a tongue-twister known as solanidine UDP-glucose glucosyltransferase. Potatoes need this enzyme in order to make a glycoalkaloid called alpha-chaconine.

In laboratory and greenhouse investigations, experimental plants containing the re-worked gene--inserted through biotechnology methods--had lower levels of glycoalkaloids. Researchers are seeking a patent for the new gene.

William R. Belknap of the ARS' Western Regional Research Center, Albany, Calif., leads the genetic engineering experiments.

The December issue of the agency's Agricultural Research magazine has a story about the investigations. The story is also on the World Wide Web at:


Scientific contact: William R. Belknap, ARS Western Regional Research Center, Albany, Calif., phone (510) 559-6072, fax (510) 559-5777,