Rice Morphology Determinant-Mediated Actin Filament Organization Contributes to Pollen Tube Growth
Rice Morphology Determinant-Mediated Actin Filament Organization Contributes to Pollen Tube Growth
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水稻形态决定因素介导的肌动蛋白丝组织有助于花粉管生长
DOI：
10.1104/pp.17.01759
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发表时间：
2018-05-01
期刊：
影响因子：
7.4
通讯作者：
Zhang, Dabing
中科院分区：
文献类型：
--
作者：
Li, Gang;Yang, Xiujuan;Zhang, Dabing
为了被子植物的成功受精，花粉管中尖端的快速生长将雄配子输送到胚珠中。花粉管内肌动蛋白结合蛋白介导的肌动蛋白细胞骨架的组织在这一极化过程中起着至关重要的作用。然而，肌动蛋白丝（F-肌动蛋白）阵列的极性和花粉管生长行为的潜在机制仍然很大程度上未知。在这里，我们证明了一种肌动蛋白组织蛋白，即水稻形态决定因子 (RMD)，一种来自水稻 (Oryza sativa) 的 II 型福明，通过调节 F-肌动蛋白阵列的极性和分布来控制花粉管生长。水稻rmd突变体在体外和体内表现出花粉管生长异常和花粉粒发芽率降低。 RMD 花粉管显示出杂乱的 F-肌动蛋白模式，顶端肌动蛋白密度和柄纵向电缆方向/排列被破坏，表明 RMD 在尖端生长过程中 F-肌动蛋白极性中的新作用。与这一作用一致，RMD 定位于水稻花粉管的尖端，这对于花粉管的生长和极性以及 F-肌动蛋白组织至关重要。此外，RMD引导的F-肌动蛋白阵列的方向和特征正向调控水稻花粉管生长过程中细胞壁成分的沉积以及细胞质流动的模式和速度。总的来说，我们的结果表明，RMD 通过调节水稻中的 F-肌动蛋白组织和阵列方向，对于花粉管生长的空间调控至关重要。这项工作提供了对尖端细胞生长和极性的见解。
For successful fertilization in angiosperms, rapid tip growth in pollen tubes delivers the male gamete into the ovules. The actin-binding protein-mediated organization of the actin cytoskeleton within the pollen tube plays a crucial role in this polarized process. However, the mechanism underlying the polarity of the actin filament (F-actin) array and behaviors in pollen tube growth remain largely unknown. Here, we demonstrate that an actin-organizing protein, Rice Morphology Determinant (RMD), a type II formin from rice (Oryza sativa), controls pollen tube growth by modulating the polarity and distribution of the F-actin array. The rice rmd mutant exhibits abnormal pollen tube growth and a decreased germination rate of the pollen grain in vitro and in vivo. The rmd pollen tubes display a disorganized F-actin pattern with disrupted apical actin density and shank longitudinal cable direction/arrangement, indicating the novel role of RMD in F-actin polarity during tip growth. Consistent with this role, RMD localizes at the tip of the rice pollen tube, which is essential for pollen tube growth and polarity as well as F-actin organization. Furthermore, the direction and characteristics of the RMD-guided F-actin array positively regulate the deposition of cell wall components and the pattern and velocity of cytoplasmic streaming during rice pollen tube growth. Collectively, our results suggest that RMD is essential for the spatial regulation of pollen tube growth via modulating F-actin organization and array orientation in rice. This work provides insights into tip-focused cell growth and polarity.