上海生科院植生生态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进展，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黄善金研究员课题组合作，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的作用，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。
该工作得到了中国科学院知识创新工程、国家科技部、国家自然科学基金委等的支持。（生物谷Bioon.com）
生物谷推荐原文出处：
Plant Cell doi:10.1105/tpc.110.081802
BENT UPPERMOST INTERNODE1 Encodes the Class II Formin FH5 Crucial for Actin Organization and Rice Development[W],[OA]
Weibing Yanga,1, Sulin Renb,1, Xiaoming Zhangc,1, Mingjun Gaoa, Shenghai Yec, Yongbin Qic, Yiyan Zhengb, Juan Wangb, Longjun Zenga, Qun Lia, Shanjin Huangb,2 and Zuhua Hea,2,3
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. The bui1 mutant displayed pleiotropic phenotypes, including bent uppermost internode, dwarfism, wavy panicle rachis, and enhanced gravitropic response. Cytological observation indicated that the growth defects of bui1 were caused mainly by inhibition of cell expansion. Map-based cloning revealed that BUI1 encodes 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 in bui1 cells. 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.
