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after nine months of storage. Two priorities for storage managers are wound-healing and sprout control. Potatoes are wounded during harvest and must heal in order to prevent infection by other pathogens. Chemist Ed Lulai, with ARS in Fargo, has identified hormonal signals stimulating the healing process. At harvest, potatoes are dormant. During storage, dormancy ends and sprout growth commences. Sprouting, in turn, results in numerous biochemical changes, which diminish the nutritional and processing qualities of potatoes. Post- harvest sprouting is typically controlled during storage with chemical inhibitors. The long-term goal of Suttle’s program is to find less-costly, non-chemical solutions to the problem by identifying the genetic cause for early-sprouting tubers. The researchers have identified internal mechanisms that signal sprouts to grow, and they are currently isolating the genes responsible for these signals. Once identified, these genes can be used in breeding programs to modify the sprouting characteristics of any given potato line. Improved nutrition is another objective: For example, at Aberdeen, the focus is on elevated protein and vitamin C content. Clearwater and Classic varieties, both released in 2008, boast 30 to 40 percent more protein than the Russet Burbank variety. At ARS’s Vegetable and Forage Crop Research Unit in Prosser, Wash., geneticists Chuck Brown and Roy Navarre are seeking increased antioxidant activity and elevated levels of phytochemicals. Together with colleagues, they’ve devised new analytical methods for detecting and measuring phytochemical concentrations in tubers. Using these methods, they found a range of phenolic concentrations—from 100 to more than 1,500 milligrams per 100 grams dry weight—in both wild and cultivated lines. Phenolics may help diminish cardiovascular disease, respiratory problems and certain cancers, the researchers say. One type, chlorogenic acid, is being tested by university cooperators for its potential to lower blood pressure. And, says Navarre, some of these potatoes have high levels of antioxidants (more than 300 micromoles Trolox equivalents per gram dry weight) that rival vegetables like spinach. The data from Prosser shows the potential for developing high-phytonutrient potatoes. But without a reliable source of disease 24 Potato Grower | AUGUST 2010