4c3b7c7a01a82a0a37a0fb1e62897d21.jpg(베이징=연합뉴스) 차대운 특파원 = 미국 연구팀이 유전체(게놈) 분석을 통해 쌀의 기원지가 중국이라는 결론을 내놓았다고 신화통신이 3일 워싱턴발로 보도했다.

   뉴욕대학 생물학자 마이클 푸루그개넌 등이 참여한 연구팀은 미국립과학원회보(PNAS) 최신호에서 현재 인류에 의해 재배되고 있는 양대 쌀 품종인 자포니카와 인디카가 8천년 전 무렵 중국의 창장(長江) 유역에서 기원했다고 밝혔다.

   쌀은 워낙 변종이 많아 과학계에서는 자포니카는 중국에서, 인디카는 인도에서 기원했다는 다중기원설과 두 품종이 원래는 같은 쌀에서 유래됐다는 단일기원설이 동시에 존재해왔다.

   연구팀은 기존에 발표된 유전체 분석 데이터베이스를 좀 더 과학화된 컴퓨터 알고리즘을 적용해 분석한 결과 자포니카와 인디카 사이의 유전적 관계가 다른 야생 쌀 품종보다 높은 것으로 나타났다고 밝혔다.

   연구팀은 이를 바탕으로 자포니카와 인디카가 한 쌀 품종에서 분화된 것이라는 결론을 내렸다.

   또한 연구팀은 쌀 유전자의 '분자시계(molecular clock)'의 분석을 통해 쌀의 기원이 대략 8천200년 전이며 자포니카와 인디카는 약 3천900년전 분화됐다고 밝혔다.

   마이클 푸루그개넌은 "쌀이 무역상 또는 이주 농민에 의해 중국에서 인도로 넘어간 후 현지 야생 쌀과 잡종이 일어난 것으로 보인다"며 "따라서 한때 인도에서 기원했다고 여겨져온 쌀 품종도 그 기원은 중국이라고 할 수 있다"고 설명했다.

Source: http://www.yonhapnews.co.kr/international/2011/05/03/0601020100AKR20110503057000083.HTML?template=3386


Rice's Origins Point to China, Genome Researchers Conclude

ScienceDaily (May 2, 2011) — 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 origin -- India as well as China.

3ad2ba0f674277d0cd743a06c71184f9.jpgThe 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 theory -- a single-origin model -- suggests that indica and japonica were domesticated once from the wild rice O. rufipogon.

Another -- a multiple-origin model -- proposes 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 datasets, some of which have been used to argue that indica and japonica rice have separate origins. Using more modern computer algorithms, however, the researchers concluded these two species have the same origin because they have a closer genetic relationship to each other than to any wild rice species found in either India or China.

In addition, the study's authors examined the phylogeny of domesticated rice by re-sequencing 630 gene fragments on selected chromosomes from a diverse set of wild and domesticated rice varieties. Using new modeling techniques, which had previously been used to look at genomic data in human evolution, their results showed that the gene sequence data was more consistent with a single origin of rice.

In their PNAS study, the investigators also used a "molecular clock" of rice genes to see when rice evolved. Depending on how the researchers calibrated their clock, they pinpointed the origin of rice at possibly 8,200 years ago, while japonica and indica split apart from each other about 3,900 years ago. The study's authors pointed out that these molecular dates were consistent with archaeological studies. Archaeologists have uncovered evidence in the last decade for rice domestication in the Yangtze Valley beginning approximately 8,000 to 9,000 years ago while domestication of rice in the India's Ganges region was around about 4,000 years ago.

"As rice was brought in from China to India by traders and migrant farmers, it likely hybridized extensively with local wild rice," explained NYU biologist Michael Purugganan, one of the study's co-authors. "So domesticated rice that we may have once thought originated in India actually has its beginnings in China."

"This study is a good example of the new insights that can be gained from combining genomics, informatics and modeling," says Barbara A. Schaal, Mary-Dell Chilton Distinguished Professor of Biology at Washington University in St. Louis, who is also a co-author. "Rice has a complicated evolutionary history with humans and has accompanied them as they moved throughout Asia. This work begins to reveal the genetic consequences of that movement."

The research was funded by a grant from the National Science Foundation Plant Genome Research Program.