Grain weight is one of the most important components of grain yield and is controlled by quantitative trait loci (QTLs) derived from natural variations in crops. However, the molecular roles of QTLs in the regulation of grain weight have not been fully elucidated. Here, we report the cloning and characterization of GW2, a new QTL that controls rice grain width and weight. Our data show that GW2 encodes a previously unknown RING-type protein with E3 ubiquitin ligase activity, which is known to function in the degradation by the ubiquitin-proteasome pathway. Loss of GW2 function increased cell numbers, resulting in a larger (wider) spikelet hull, and it accelerated the grain milk filling rate, resulting in enhanced grain width, weight and yield. Our results suggest that GW2 negatively regulates cell division by targeting its substrate(s) to proteasomes for regulated proteolysis. The functional characterization of GW2 provides insight into the mechanism of seed development and is a potential tool for improving grain yield in crops.
粒重是作物產(chǎn)量的重要構(gòu)成因素之一，由來(lái)源于自然變異的數(shù)量性狀基因座(QTL)控制。然而調(diào)節(jié)粒重QTL的分子功能并未完全得以闡明。本文我們報(bào)道了克隆和鑒定一個(gè)控制水稻粒寬和粒重新的QTL GW2。我們的數(shù)據(jù)表明GW2編碼一個(gè)之前未知的RING型蛋白，具有E3泛素連接酶活性。E3泛素連接酶在通過(guò)泛素蛋白酶體通路降解蛋白中發(fā)揮功能。GW2功能喪失增加了細(xì)胞的數(shù)目，導(dǎo)致穎殼變大，灌漿速率加快，從而使粒寬和粒重增加，產(chǎn)量提高。我們的結(jié)果表明GW2通過(guò)將其底物錨定到蛋白酶體進(jìn)行降解，從而負(fù)調(diào)節(jié)細(xì)胞的分裂。GW2的功能鑒定加深了對(duì)種子發(fā)育機(jī)制了解，為提高作物產(chǎn)量提供了可能。
結(jié)果：GW2的圖位克?。?EM>GW2的序列分析和自然變異；GW2編碼一個(gè)具有E3泛素連接酶活性的RING蛋白；GW2的亞細(xì)胞定位和組織定位。 GW2增加了粒寬和粒重并影響其他性狀；GW2增加細(xì)胞數(shù)目和加快灌漿速率。