近日，中科院植物研究所葛頌研究組和系統(tǒng)與進(jìn)化植物學(xué)國(guó)家重點(diǎn)實(shí)驗(yàn)室海外學(xué)術(shù)顧問、密歇根州立大學(xué)桑濤教授合作，通過對(duì)水稻落粒基因sh4的群體遺傳學(xué)分析,，揭示了選擇對(duì)該基因影響，并探討了水稻馴化的速率和可能機(jī)制,。該成果發(fā)表在最近一期New Phytologist（2009, 184: 708－720）雜志上,。
作物的不落粒對(duì)于作物生產(chǎn)具有重要意義。水稻落?；騭h4是第一個(gè)被鑒定控制作物落粒的數(shù)量性狀主效基因,，由密歇根州立大學(xué)桑濤教授小組發(fā)表在2006年Science雜志上。為了進(jìn)一步探討該基因的進(jìn)化歷史,，進(jìn)而了解水稻馴化過程和機(jī)制,，葛頌課題組和桑濤教授合作，對(duì)該基因的分子群體遺傳學(xué)進(jìn)行了研究,。
通過選取秈稻和粳稻（Oryza sativa ssp. indica和O. sativa ssp. japonica）代表性品種以及代表水稻野生祖先種O. nivara和O. rufipogon的群體樣品,，他們對(duì)控制水稻落粒的兩個(gè)位點(diǎn)sh4和qSH1的變異進(jìn)行了研究，發(fā)現(xiàn)不落粒sh4的等位基因在所有栽培稻中都被固定下來,，多態(tài)性極低,。進(jìn)一步的系統(tǒng)發(fā)育和群體遺傳分析表明，sh4等位基因?yàn)閱未纹鹪?，在水稻馴化過程中通過人工選擇而得以固定,。相反，對(duì)qSH1的選擇在栽培稻indica和japonica中都不明顯,。進(jìn)一步的分析表明,，人類對(duì)sh4基因的選擇很強(qiáng)，以至于該基因在100年內(nèi)就被固定在栽培稻的居群中,，因此推測(cè)考古學(xué)所報(bào)道的不落粒表型的緩慢固定可能是由于在水稻培育的早期對(duì)變異相對(duì)較弱的選擇,，而不是對(duì)于sh4的選擇,。
該研究從基因進(jìn)化的角度為揭示栽培稻的起源提供了重要資料。（生物谷Bioon.com）
生物谷推薦原始出處：
New Phytologist Volume 184 Issue 3, Pages 708 - 720
Selection on grain shattering genes and rates of rice domestication
Lin-Bin Zhang 1 , Qihui Zhu 1 , Zhi-Qiang Wu 1 , Jeffrey Ross-Ibarra 2 , Brandon S. Gaut 2 , Song Ge 1 and Tao Sang 3
1 State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China; 2 Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697, USA; 3 Department of Plant Biology, Michigan State University, East Lansing, MI 48824, USA
Molecular cloning of major quantitative trait loci (QTLs) responsible for the reduction of rice grain shattering, a hallmark of cereal domestication, provided opportunities for in-depth investigation of domestication processes.
Here, we studied nucleotide variation at the shattering loci, sh4 and qSH1, for cultivated rice, Oryza sativa ssp. indica and Oryza sativa ssp. japonica, and the wild progenitors, Oryza nivara andOryza rufipogon.
The nonshattering sh4 allele was fixed in all rice cultivars, with levels of sequence polymorphism significantly reduced in both indica and japonica cultivars relative to the wild progenitors. The sh4 phylogeny together with the neutrality tests and coalescent simulations suggested that sh4 had a single origin and was fixed by artificial selection during the domestication of rice. Selection on qSH1 was not detected in indica and remained unclear in japonica.
Selection on sh4 could be strong enough to have driven its fixation in a population of cultivated rice within a period of c. 100 yr. The slow fixation of the nonshattering phenotype observed at the archeological sites might be a result of relatively weak selection on mutations other than sh4 in early rice cultivation. The fixation of sh4 could have been achieved later through strong selection for the optimal phenotype.
