Song Xian-Jun, Huang Wei, Shi Min, Zhu Mei-Zhen, Lin Hong-Xuan
National Key Laboratory of Plant Molecular Genetics, Shanghai Institute of Plant Physiology and Ecology, Shanghai Institute for Biological Sciences, The Chinese Academy of Sciences, 300 Fenglin Road, Shanghai 200032, China.
Nat Genet. 2007 May;39(5):623-30. doi: 10.1038/ng2014. Epub 2007 Apr 8.
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.
粒重是籽粒产量的最重要组成部分之一，受作物自然变异衍生的数量性状基因座（QTL）控制。然而，QTL在粒重调控中的分子作用尚未完全阐明。在此，我们报告了GW2的克隆与表征，GW2是一个控制水稻粒宽和粒重的新QTL。我们的数据表明，GW2编码一种以前未知的具有E3泛素连接酶活性的RING型蛋白，已知其在泛素-蛋白酶体途径介导的降解过程中发挥作用。GW2功能缺失增加了细胞数量，导致颖壳更大（更宽），并加快了籽粒灌浆速率，从而增加了粒宽、粒重和产量。我们的结果表明，GW2通过将其底物靶向蛋白酶体进行调控性蛋白水解来负调控细胞分裂。GW2的功能表征为种子发育机制提供了见解，并且是提高作物籽粒产量的潜在工具。
