Cytoskeleton Dynamics Are Necessary for Early Events of Lateral Root Initiation in Arabidopsis

First author: Amaya Vilches Barro; Affiliations: University of Heidelberg (海德堡大学): Heidelberg, Germany

Corresponding author: Alexis Maizel

How plant cells re-establish differential growth to initiate organs is poorly understood. Morphogenesis of lateral roots relies on the asymmetric cell division of initially symmetric founder cells. This division is preceded by the tightly controlled asymmetric radial expansion of these cells. The cellular mechanisms that license and ensure the coordination of these events are unknown. Here, we quantitatively analyze microtubule and F-actin dynamics during lateral root initiation. Using mutants and pharmacological and tissue-specific genetic perturbations, we show that dynamic reorganization of both microtubule and F-actin networks is necessary for the asymmetric expansion of the founder cells. This cytoskeleton remodeling intertwines with auxin signaling in the pericycle and endodermis in order for founder cells to acquire a basic polarity required for initiating lateral root development. Our results reveal the conservation of cell remodeling and polarization strategies between the Arabidopsis zygote and lateral root founder cells. We propose that coordinated, auxin-driven reorganization of the cytoskeleton licenses asymmetric cell growth and divisions during embryonic and post-embryonic organogenesis.

有关植物细胞如何重新建立分化生长以起始新器官的形成这方面的研究还不够透彻。侧根的形态建成依赖于起始的、对称性建成细胞（founder cell）的不对称细胞分裂。在该分裂之前，这些细胞受到了严格的径向不对称扩张调控。然而，该现象潜在的分子调控机制还不清楚。本文中，作者定量分析了侧根起始过程中微管和F-肌动蛋白动态变化。利用突变体、药理学及组织特异性基因扰动，作者发现微管和F-肌动蛋白的动态重组对于建成细胞的不对称分裂是必须的。该细胞骨架重塑与根中柱鞘和内皮层组织中的生长素信号紧密相关，使得建成细胞能够获得一个基本的极性，从而能够起始侧根的发育。本文的结果揭示了拟南芥合子与侧根建成细胞之间细胞重塑和极性策略的保守性。作者认为协同的、由生长素驱动的细胞骨架重组使得胚胎发育和胚后器官形成过程中细胞的不对称生长和分裂成为可能。

通讯：Alexis Maizel (http://www.maizel-lab.org/)

个人简介：2002年，巴黎第五大学和巴黎高等师范学院，博士。

研究方向：拟南芥侧根形态建成的细胞学基础；小RNA在拟南芥侧根形成中的作用。

doi: https://doi.org/10.1016/j.cub.2019.06.039

Journal: Current Biology

Published date: July 18, 2019