Increased crop yields are required to support rapid population growth worldwide. Grain weight is a key component of rice yield, but the underlying molecular mechanisms that control it remain elusive. Here, we report the cloning and characterization of a new quantitative trait locus (QTL) for the control of rice grain length, weight and yield. This locus, GL3.1, encodes a protein phosphatase kelch (PPKL) family — Ser/Thr phosphatase. GL3.1 is a member of the large grain WY3 variety, which is associated with weaker dephosphorylation activity than the small grain FAZ1 variety. GL3.1-WY3 influences protein phosphorylation in the spikelet to accelerate cell division, thereby resulting in longer grains and higher yields. Further studies have shown that GL3.1 directly dephosphorylates its substrate, Cyclin-T1;3, which has only been rarely studied in plants. The downregulation of Cyclin-T1;3 in rice resulted in a shorter grain, which indicates a novel function for Cyclin-T in cell cycle regulation. Our findings suggest a new mechanism for the regulation of grain size and yield that is driven through a novel phosphatase-mediated process that affects the phosphorylation of Cyclin-T1;3 during cell cycle progression, and thus provide new insight into the mechanisms underlying crop seed development. We bred a new variety containing the natural GL3.1 allele that demonstrated increased grain yield, which indicates that GL3.1 is a powerful tool for breeding high-yield crops.
全球人口的快速增長需要作物產(chǎn)量的增加。粒重是水稻產(chǎn)量的重要組成部分，但我們對其潛在的分子機制還不甚了解，本文，我們報道了一個新的控制水稻粒長、粒重和產(chǎn)量QTL位點GL3.1的克隆和鑒定，該基因編碼一個屬于蛋白磷酸酶PPKL家族的絲氨酸/蘇氨酸磷酸酶。GL3.1是大粒品種WY3的一個成員，該蛋白的去磷酸化活性比小粒品種FAZ1弱。GL3.1-WY3影響了小穗中的蛋白磷酸化而加速細(xì)胞分裂，從而使籽粒更長、產(chǎn)量增加。進(jìn)一步分析表明GL3.1能直接去磷酸化底物細(xì)胞周期蛋白T1;3，T1;3很少在植物中報道，它在水稻中表達(dá)下調(diào)會導(dǎo)致籽粒變短，表明Cyclin-T在細(xì)胞周期調(diào)控方面有新功能。我們的發(fā)現(xiàn)暗示一種新的調(diào)控籽粒大小和產(chǎn)量的新機制受一種新的磷酸化酶介導(dǎo)的進(jìn)程驅(qū)動，該進(jìn)程影響細(xì)胞周期進(jìn)程中Cyclin-T1;3蛋白的磷酸化，這能讓我們更多的了解到作物種子發(fā)育機制。我們通過育出含有自然GL3;1等位基因而增加水稻產(chǎn)量，這表明該GL3.1對高產(chǎn)育種提供了更有利的工具。