我国水稻株高调控研究获重要进展

中国科学院上海生科院植物生理生态研究所植物分子遗传国家重点实验室何祖华研究组在水稻株高发育的调控研究上取得新的重要进展，其研究成果于2月9日在线发表于植物科学研究权威期刊Plant Cell。水稻株高是控制水稻产量的重要农艺性状，主要由水稻节间的伸长调节。水稻最上节间的伸长可以促进幼穗的抽出，进而开花、授粉和灌浆。因此，最上节间的发育是影响水稻产量的重要节点。继克隆和功能分析了水稻长节间基因ELONGATED UPPERMOST INTERNODE（Eui）后（Zhu et al.，2006，Plant Cell）,该研究组一直致力于水稻节间发育的研究，成功克隆了BENT UPPERMOST INTERNODE1（BUI1）基因并系统阐述了BUI1蛋白的生理和生化功能。BUI1编码一个植物特异的Class Ⅱ formin蛋白，调控细胞微丝骨架（actin cytoskeleton）的装配和动态变化。微丝骨架是细胞形态和多种生理过程的基础。BUI1的突变导致细胞中F-actin含量降低、actin bundles数目减少，细胞的伸长和极性扩展受到抑制，进而影响了BUI1突变体植株的节间发育，表现为最上节间严重缩短，呈弯曲生长。通过与中科院植物所研究员黄善金课题组合作，他们系统分析了BUI1的生化功能，证明BUI1参与了微丝骨架装配的各个过程，并呈现其特有的调控性能。该研究通过一系列体内染色和体外生化实验，证明Class Ⅱ成员BUI1是微丝骨架的重要调控因子，在高等植物微丝骨架装配和生长发育中发挥重要作用，该研究同时为水稻株高发育调节提供了一个新的研究方向。来源：《科学时报》 (2011-2-15 A1 要闻)论文摘要：The actin cytoskeleton is an important regulator of cell expansion and morphogenesis in plants. However, the molecular mechanisms linking the actin cytoskeleton to these processes remain largely unknown. Here, we report the functional analysis of rice (Oryza sativa)FH5/BENT UPPERMOST INTERNODE1(BUI1), which encodes a formin-type actin nucleation factor and affects cell expansion and plant morphogenesis in rice. Thebui1mutant displayed pleiotropic phenotypes, including bent uppermost internode, dwarfism, wavy panicle rachis, and enhanced gravitropic response. Cytological observation indicated that the growth defects ofbui1were caused mainly by inhibition of cell expansion. Map-based cloning revealed thatBUI1encodes the class II formin FH5. FH5 contains a phosphatase tensin-like domain at its amino terminus and two highly conserved formin-homology domains, FH1 and FH2. In vitro biochemical analyses indicated that FH5 is capable of nucleating actin assembly from free or profilin-bound monomeric actin. FH5 also interacts with the barbed end of actin filaments and prevents the addition and loss of actin subunits from the same end. Interestingly, the FH2 domain of FH5 could bundle actin filaments directly and stabilize actin filaments in vitro. Consistent with these in vitro biochemical activities of FH5/BUI1, the amount of filamentous actin decreased, and the longitudinal actin cables almost disappeared inbui1cells. The FH2 or FH1FH2 domains of FH5 could also bind to and bundle microtubules in vitro. Thus, our study identified a rice formin protein that regulates de novo actin nucleation and spatial organization of the actin filaments, which are important for proper cell expansion and rice morphogenesis.论文详细信息：http://www.cnrri.cn/zjww/Detail.aspx?id=20016979