Origin of <em>Oryza sativa</em> in China Inferred by Nucleotide Polymorphisms of Organelle DNA

China is rich of germplasm resources of common wild rice (Oryza rufipogon Griff.) and Asian cultivated rice (O. sativa L.) which consists of two subspecies, indica and japonica. Previous studies have shown that China is one of the domestication centers of O. sativa. However, the geographic origin and the domestication times of O. sativa in China are still under debate. To settle these disputes, six chloroplast loci and four mitochondrial loci were selected to examine the relationships between 50 accessions of Asian cultivated rice and 119 accessions of common wild rice from China based on DNA sequence analysis in the present study. The results indicated that Southern China is the genetic diversity center of O. rufipogon and it might be the primary domestication region of O. sativa. Molecular dating suggested that the two subspecies had diverged 0.1 million years ago, much earlier than the beginning of rice domestication. Genetic differentiations and phylogeography analyses indicated that indica was domesticated from tropical O. rufipogon while japonica was domesticated from O. rufipogon which located in higher latitude. These results provided molecular evidences for the hypotheses of (i) Southern China is the origin center of O. sativa in China and (ii) the two subspecies of O. sativa were domesticated multiple times.中国拥有丰富的普通野生稻（Oryza rufipogon Griff.）与亚洲栽培稻（O. sativa L.）种质资源，亚洲栽培稻包含籼稻（indica）和粳稻（japonica）两个亚种。既往研究表明，中国是亚洲栽培稻的驯化起源中心之一。然而，中国境内亚洲栽培稻的地理起源与驯化时间仍存在学术争议。为解决这一争端，本研究基于DNA序列分析，选取6个叶绿体基因座（chloroplast loci）与4个线粒体基因座（mitochondrial loci），对中国境内50份亚洲栽培稻种质与119份普通野生稻种质的亲缘关系进行了分析。结果显示，华南地区是普通野生稻的遗传多样性中心，同时可能是亚洲栽培稻的原始驯化区域。分子定年（Molecular dating）结果表明，两个亚种的分化时间距今约0.1百万年，远早于水稻驯化的起始时间。遗传分化与系统地理学（phylogeography）分析显示，籼稻由热带普通野生稻驯化而来，而粳稻则由分布于较高纬度地区的普通野生稻驯化而来。上述研究结果为两项假说提供了分子生物学证据：其一，华南地区是中国境内亚洲栽培稻的起源中心；其二，亚洲栽培稻的两个亚种经历了多次独立驯化事件。