【PNAS】大规模基因重测序确认亚洲栽培稻起源于中国
PNAS:大规模基因重测序确认亚洲栽培稻起源于中国
2011/05/04 14:16:26
美国研究人员在一项通过大规模基因重测序分析稻米进化史的研究中确认，亚洲栽培稻起源于中国，最早可能8000多年前就出现在中国长江流域。亚洲栽培稻是世界上最古老的农作物物种之一。此前曾有研究认为，亚洲栽培稻有两个起源地——印度和中国。但5月2日刊登在美国《国家科学院院刊》（PNAS）一项新研究说：“分子学证据表明（亚洲）栽培稻只有单一起源……最早出现在中国长江流域。”亚洲栽培稻具有籼稻和粳稻两个主要亚种，其起源相应也出现两种理论，其中一种为单一起源理论，即籼稻和粳稻均由野生稻栽培而来；而另一种多起源理论认为，籼稻和粳稻在亚洲不同地点分别栽培而来。近年来，由于科学界观测到籼稻和粳稻更多的遗传差异性，多起源理论稍占上风。美国纽约大学等机构的研究人员利用此前已公布的数据库以及更先进的计算机运算规则，重新分析了亚洲栽培稻的进化史。他们的结论是，籼稻和粳稻具有同一起源，因为二者尽管具有诸多遗传差异性，但彼此间的遗传关系仍比与印度或中国发现的任何野生稻种类的遗传关系都要近。他们还对栽培稻和野生稻染色体上630个基因片段进行了重测序，结果也是基因测序数据与单起源理论更一致。研究人员利用稻米基因的分子钟分析了亚洲栽培稻的进化时间。他们认为，亚洲栽培稻大约8200年前开始出现，而籼稻和粳稻在大约3900年前开始分离。这一结论与考古学发现相一致。考古学家发现，中国长江流域8000年至9000年前出现了栽培稻，而印度恒河流域大约4000年前才开始出现栽培稻。参与研究的纽约大学生物学家迈克尔·普鲁加南说：“随着栽培稻通过商人以及农民由中国传入印度，它很可能与当地野生稻进行了大范围杂交，这就是为什么我们曾认为栽培稻可能起源于印度，但实际上是来自于中国。”
Proceedings of the National Academy of Sciences DOI： 10.1073/pnas.1104686108
Molecular evidence for a single evolutionary origin of domesticated rice
Molina, Jeanmaire; Sikora, Martin; Garud, Nandita; Flowers, Jonathan M.; Rubinstein, Samara; Reynolds, Andy; Huang, Pu; Jackson, Scott; Schaal, Barbara A.; Bustamante, Carlos D.; Boyko, Adam R.; Purugganan, Michael D
Asian rice, Oryza sativa, is one of world’s oldest and most important crop species. Rice is believed to have been domesticated ?9,000 y ago, althoughdebate on its origin remains contentious. A single-origin model suggests that two main subspecies of Asian rice, indica and japonica, were domesticated from the wild rice O. rufipogon. In contrast, the multiple independent domestication model proposes that these two major rice types were domesticated separatelyand in different parts of the species range of wild rice. This latter view has gained much support from the observation ofstrong genetic differentiation between indica and japonica as well as several phylogenetic studies of rice domestication. We reexamine the evolutionary history of domesticated riceby resequencing 630 gene fragments on chromosomes 8, 10, and 12 from a diverse set of wild and domesticated rice accessions.Using patterns of SNPs, we identify 20 putative selective sweeps on these chromosomes in cultivated rice. Demographic modelingbased on these SNP data and a diffusion-based approach provide the strongest support for a single domestication origin ofrice. Bayesian phylogenetic analyses implementing the multispecies coalescent and using previously published phylogeneticsequence datasets also point to a single origin of Asian domesticated rice. Finally, we date the origin of domestication at?8,200–13,500 y ago, depending on the molecular clock estimate that is used, which is consistent with known archaeologicaldata that suggests rice was first cultivated at around this time in the Yangtze Valley of China.