VLN2 Regulates Plant Architecture by Affecting Microfilament Dynamics and Polar Auxin Transport in Rice[OPEN]
VLN2 Regulates Plant Architecture by Affecting Microfilament Dynamics and Polar Auxin Transport in Rice[OPEN]
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DOI：
10.1105/tpc.15.00581
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发表时间：
2015-10
期刊：
影响因子：
11.6
通讯作者：
Shengyang Wu;Yurong Xie;Junjie Zhang;Yulong Ren;Xin Zhang;Jiulin Wang;Xiuping Guo;Fuqing Wu
中科院分区：
文献类型：
--
作者：
Shengyang Wu;Yurong Xie;Junjie Zhang;Yulong Ren;Xin Zhang;Jiulin Wang;Xiuping Guo;Fuqing Wu
一个水稻VILLIN2突变体，随着微丝动力学的改变，显示出与PIN2蛋白膜定位减弱和生长素极性运输减少相关的畸形器官。微丝作为一种基本的、动态的细胞骨架网络，受多种肌动蛋白结合蛋白的调控。绒毛蛋白属于绒毛蛋白/明胶蛋白超家族中的一种，其在单子叶植物中的功能尚不清楚。在这里，我们报道了一个水稻VILLIN2(VLN2)缺陷突变体的分离和鉴定，该突变体在苗期表现出畸形的器官，包括扭曲的根和新梢。细胞检查显示，vln2突变体的扭曲表型主要是由器官两侧细胞的不对称扩张引起的。VLN2在生长中的组织中优先表达，与在发育中的器官中调节细胞扩张的作用一致。在生物化学方面，VLN2在体外表现出保守的肌动蛋白细丝束、切断和封顶活性，在体内证实了捆绑和稳定活性。与这些发现一致的是，vln2突变植株比野生型表现出更具活力的肌动蛋白细胞骨架网络。我们发现，vln2突变植株表现出高度敏感的向重力性反应，更快地回收生长素外排载体PIN2，并改变生长素的分布。综上所述，我们的结果表明，VLN2通过调节MF动态、PIN2的循环和生长素的极性运输，在调节植物结构方面发挥了重要作用。
A rice VILLIN2 mutant, with altered microfilament dynamics, displays malformed organs associated with weakened membrane localization of the PIN2 protein and reduced polar auxin transport. 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 that VLN2 plays an important role in regulating plant architecture by modulating MF dynamics, recycling of PIN2, and polar auxin transport.