State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China.
State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100193, China; Joint Laboratory for International Cooperation in Crop Molecular Breeding, Ministry of Education, China Agricultural University, Beijing 100193, China.
Mol Plant. 2022 Jun 6;15(6):1008-1023. doi: 10.1016/j.molp.2022.04.008. Epub 2022 Apr 28.
Tip growth is an extreme form of polarized cell expansion that occurs in all eukaryotic kingdoms to generate highly elongated tubular cells with specialized functions, including fungal hyphae, animal neurons, plant pollen tubes, and root hairs (RHs). RHs are tubular structures that protrude from the root epidermis to facilitate water and nutrient uptake, microbial interactions, and plant anchorage. RH tip growth requires polarized vesicle targeting and active exocytosis at apical growth sites. However, how apical exocytosis is spatially and temporally controlled during tip growth remains elusive. Here, we report that the Qa-Soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) SYP121 acts as an effector of Rho of Plants 2 (ROP2), mediating the regulation of RH tip growth. We show that active ROP2 promotes SYP121 targeting to the apical plasma membrane. Moreover, ROP2 directly interacts with SYP121 and promotes the interaction between SYP121 and the R-SNARE VAMP722 to form a SNARE complex, probably by facilitating the release of the Sec1/Munc18 protein SEC11, which suppresses the function of SYP121. Thus, the ROP2-SYP121 pathway facilitates exocytic trafficking during RH tip growth. Our study uncovers a direct link between an ROP GTPase and vesicular trafficking and a new mechanism for the control of apical exocytosis, whereby ROP GTPase signaling spatially regulates SNARE complex assembly and the polar distribution of a Q-SNARE.
顶端生长是一种极端的极化细胞扩展形式，发生在所有真核生物王国中，以产生具有特殊功能的高度伸长管状细胞，包括真菌菌丝、动物神经元、植物花粉管和根毛（RH）。RH 是从根表皮突出的管状结构，有助于水和养分的吸收、微生物相互作用和植物固定。RH 顶端生长需要极化囊泡靶向和在顶端生长部位的活跃胞吐作用。然而，顶端胞吐作用如何在空间和时间上受到顶端生长的控制仍然难以捉摸。在这里，我们报告说 Qa-可溶性 N-乙基马来酰亚胺敏感因子附着蛋白受体（SNARE）SYP121 作为植物 Rho 2（ROP2）的效应物发挥作用，调节 RH 顶端生长。我们表明，活性 ROP2 促进 SYP121 靶向到顶端质膜。此外，ROP2 直接与 SYP121 相互作用，并促进 SYP121 与 R-SNARE VAMP722 之间的相互作用，形成 SNARE 复合物，可能通过促进 SEC11 蛋白 SEC11 的释放来促进 SYP121 的功能，SEC11 抑制 SYP121 的功能。因此，ROP2-SYP121 途径促进了 RH 顶端生长过程中的胞吐作用。我们的研究揭示了 ROP GTPase 与囊泡运输之间的直接联系，以及控制顶端胞吐作用的新机制，即 ROP GTPase 信号在空间上调节 SNARE 复合物的组装和 Q-SNARE 的极性分布。
