The Plant Cell:中国农科院万建民研究组发表微丝调节水稻形态发育
2015年10月23日，《The Plant Cell》杂志上发表中国农业科学院作物科学研究所万建民教授领导的作物功能基因组学创新团队的相关研究成果，研究发现微丝结合蛋白Villin2(VLN2)通过调节微丝的动态变化，影响细胞膨大、生长素极性运输以及水稻的生长发育。吴盛阳博士为论文第一作者，万建民教授为论文通讯作者。研究由作科所和南京农业大学作物遗传和种质创新国家重点实验室合作完成。
据悉，微丝是细胞骨架的一种，它通过动态变化来调节众多细胞学过程。目前的研究表明，微丝参与到细胞减数分裂、有丝分裂、囊泡和细胞器运动和细胞生长。尽管最近的研究表明，微丝可以影响植物形态发育，但是其中的机制尚不清楚。
该团队长期从事水稻功能基因方面的研究。本研究中发现的突变体几乎所有组织的形态都出现改变，比如在幼苗期扭曲生长的根和茎、扭曲的叶片、穗型和皱缩的种子。细胞学分析表明，突变体中细胞变小，但是细胞数目没发生明显变化;对突变基因的克隆表明，VLN2(编码一个肌动蛋白结合蛋白)功能丧失导致突变表型。该课题组通过体内和体外实验证明了VLN2具有剪切、成束和封盖微丝的功能。此外，该课题组从vln2突变体对重力响应超敏感入手，发现了突变体根中生长素输出载体PIN2循环异常、生长素不对称分布等表型。这表明VLN2可能通过调节微丝影响PIN循环，继而影响了生长素极性运输和分布，再影响到细胞膨大和器官异常。该研究为进一步阐明微丝与植物发育的机制研究奠定了基础，对水稻形态改良提供理论支持。
原文链接：
VLN2 Regulates plant Architecture by Affecting Microfilament Dynamics and Polar Auxin Transport in Rice
原文摘要：
As a fundamental and dynamic cytoskeleton network, microfilaments (MFs) are regulated by diverse actin binding proteins (ABPs). Villins are one type of ABPs belonging to the villin/gelsolin superfamily, and their function is poorly understood in monocotyledonous plants. Here, we report the isolation and characterization of a rice (Oryza sativa) mutant defective in VILLIN2 (VLN2), which exhibits malformed organs, including twisted roots and shoots at the seedling stage. Cellular examination revealed that the twisted phenotype of the vln2 mutant is mainly caused by asymmetrical expansion of cells on the opposite sides of an organ. VLN2 is preferentially expressed in growing tissues, consistent with a role in regulating cell expansion in developing organs. Biochemically, VLN2 exhibits conserved actin filament bundling, severing and capping activities in vitro, with bundling and stabilizing activity being confirmed in vivo. In line with these findings, the vln2 mutant plants exhibit a more dynamic actin cytoskeleton network than the wild type. We show that vln2 mutant plants exhibit a hypersensitive gravitropic response, faster recycling of PIN2 (an auxin efflux carrier), and altered auxin distribution. Together, our results demonstrate thatVLN2 plays an important role in regulating plant architecture by modulating MFdynamics, recycling of PIN2, and polar auxin transport.
作者：万建民
