The domestication of crops involves a complex process of selection in plant evolution and is associated with changes in the DNA regulating agronomically important traits. Here we report the cloning of a newly identified QTL, qSW5 (QTL for seed width on chromosome 5), involved in the determination of grain width in rice. Through fine mapping, complementation testing and association analysis, we found that a deletion in qSW5 resulted in a significant increase in sink size owing to an increase in cell number in the outer glume of the rice flower; this trait might have been selected by ancient humans to increase yield of rice grains. In addition, we mapped two other defective functional nucleotide polymorphisms of rice domestication-related genes with genome-wide RFLP polymorphisms of various rice landraces. These analyses show that the qSW5 deletion had an important historical role in artificial selection, propagation of cultivation and natural crossings in rice domestication, and shed light on how the rice genome was domesticated.
作物的人工馴化涉及到植物進化中的復(fù)雜選擇過程，與控制重要農(nóng)藝性狀的DNA的改變有關(guān)。本文我們克隆了一個新鑒定出來的控制水稻粒寬的QTL，qSW5。通過精細定位、互補實驗和關(guān)聯(lián)分析，我們發(fā)現(xiàn)qSW5的缺失引起水稻小花外穎的細胞數(shù)目增加而使穎殼顯著變大。這一性狀可能被古代人類所選擇以增加水稻產(chǎn)量。另外，我們還在各種水稻地方品種中利用全基因組RFLP多態(tài)性定位到了馴化相關(guān)基因的兩個功能喪失核苷酸多態(tài)。這些分析表明qSW5的缺失在人工馴化過程中人工的選擇、栽培技術(shù)的傳播以及水稻的自然雜交等都發(fā)揮重要的歷史作用，同時有助于闡明水稻基因組是如何被人工馴化的。