Weedy rice is a feral form of rice that infests paddies worldwide and aggressively outcompetes cultivated varieties. A new study led by biologists at Washington University in St. Louis shows that weed populations have evolved multiple times from cultivated rice, and a strikingly high proportion of contemporary Asian weed strains can be traced to a few Green Revolution cultivars that were widely grown in the late 20th century.
Weedy rice — or rice gone rogue — costs U.S. farmers more than $45 million annually. A team led by Washington University in St. Louis will characterize the genetic basis and origins of the traits that allow weedy rice to invade rice fields, reduce yields and contaminate harvests.
Researchers led by Kenneth M. Olsen in Arts & Sciences used a new imaging technique to reveal a takeover strategy that has worked for weedy rice over and over again: roots that minimize below-ground contact with other plants.
We tend to assume that domestication is a one-way street and that, once domesticated, crop plants stay domesticated. A new study of rice shows, however, that different methods of farming change the evolutionary pressures on crop plants, and the plants easily “de-domesticate,” evolving to take advantage of these opportunities.
With the help of modern genetic technology and the resources of the International Rice GeneBank, which contains more than 112,000 different types of rice, evolutionary biologist Kenneth Olsen has been able to look back in time at the double domestication of rice (in Asia and in Africa) and its double “de-domestication” to form two weedy strains. Olsen predicts the introduction of pesticide-resistant rice will drive ever faster adaptation in weedy rice.