Rice originated in China, a team of genome researchers has concluded in a study tracing back thousands of years of evolutionary history through large-scale gene re-sequencing. Their findings, which appear in the latest issue of the Proceedings of the National Academy of Sciences (PNAS), indicate that domesticated rice may have first appeared as far back as approximately 9,000 years ago in the Yangtze Valley of China. Previous research suggested domesticated rice may have two points of originIndia as well as China.
The study was conducted by researchers from New York University's Center for Genomics and Systems Biology and its Department of Biology, Washington University in St. Louis' Department of Biology, Stanford University's Department of Genetics, and Purdue University's Department of Agronomy.
Asian rice, Oryza sativa, is one of world's oldest crop species. It is also a very diverse crop, with tens of thousands of varieties known throughout the world. Two major subspecies of rice japonica and indica represent most of the world's varieties. Sushi rice, for example, is a type of japonica, while most of the long-grain rice in risottos are indica. Because rice is so diverse, its origins have been the subject of scientific debate. One theorya single-origin modelsuggests that indica and japonica were domesticated once from the wild rice O. rufipogon.
Anothera multiple-origin modelproposes that these two major rice types were domesticated separately and in different parts of Asia. The multiple-origin model has gained currency in recent years as biologists have observed significant genetic differences between indica and japonica, and several studies examining the evolutionary relationships among rice varieties supported more than domestication in both India and China.
In the PNAS study, the researchers re-assessed the evolutionary history, or phylogeny, of domesticated rice using previously published data
|Contact: James Devitt|
New York University