The scientists analyzed DNA markers in 261 wild and 98 cultivated potato varieties to assess whether the domestic potato arose from a single wild progenitor or whether it arose multiple times - and the results were clear, says David Spooner, the USDA research scientist who led the study.
"In contrast to all prior hypotheses of multiple origins of the cultivated potato, we have identified a single origin from a broad area of southern Peru," says Spooner, who is also a UW-Madison professor of horticulture. "The multiple-origins theory was based in part on the broad distribution of potatoes from north to south across many different habitats, through morphological resemblance of different wild species to cultivated species, and through other data. Our DNA data, however, shows that in fact all cultivated potatoes can be traced back to a single origin in southern Peru."
The earliest archaeological evidence suggests that potatoes were domesticated from wild relatives by indigenous agriculturalists more than 7,000 years ago, says Spooner. Today, the potato - an international dietary staple - is a major crop in both the United States and in Wisconsin, which is fourth in the nation for potato production.
Potato diseases such as late blight can cause significant economic damage to farmers in America and throughout the world.
"As a taxonomist, my job is to help determine what is a species and to classify those species into related groups," Spooner explains. "Other scientists use these results as a kind of roadmap to guide them in the use of the
Contact: David Spooner
University of Wisconsin-Madison