Two mechanisms regulate directional cell growth in Arabidopsis lateral roots

First author: Charlotte Kirchhelle; Affiliations: University of Oxford (牛津大学): Oxford, UK

Corresponding author: Charlotte Kirchhelle

Morphogenesis in plants depends critically on directional (anisotropic) growth. This occurs principally perpendicular to the net orientation of cellulose microfibrils (CMFs), which is in turn controlled by cortical microtubules (CMTs). In young lateral roots of Arabidopsis thaliana, growth anisotropy also depends on RAB-A5c, a plant-specific small GTPase that specifies a membrane trafficking pathway to the geometric edges of cells. Here we investigate the functional relationship between structural anisotropy at faces and RAB-A5c activity at edges during lateral root development. We show that surprisingly, inhibition of RAB-A5c function is associated with increased CMT/CMF anisotropy. We present genetic, pharmacological, and modelling evidence that this increase in CMT/CMF anisotropy partially compensates for loss of an independent RAB-A5c-mediated mechanism that maintains anisotropic growth in meristematic cells. We show that RAB-A5c associates with CMTs at cell edges, indicating that CMTs act as an integration point for both mechanisms controlling cellular growth anisotropy in lateral roots.

植物的形态建成依赖于各向异性的生长。细胞的生长方向主要垂直于纤维素微纤丝（CMF）网方向，而这又受到周质微管（CMT）的调控。在拟南芥新生的侧根中，生长的各向异性还依赖于一个植物特异性的小GTP酶RAB-A5c，该酶主要作用于朝向细胞几何形状边缘的膜运输通路。本文中，作者研究了侧根发育过程中细胞面向结构异向生长与边缘RAB-A5c活性之间的功能相关性。作者发现抑制RAB-A5c的功能增加了细胞中CMT/CMF的各向异性。作者进一步通过遗传学、药理学和建模证据显示这种CMT/CMF各向异性的增加可以部分补偿一个RAB-A5c独立介导的机制的缺失，而该机制能够维持分生组织细胞中的各向异性生长。本文的研究显示RAB-A5c与CMT在细胞边缘具有相关性，揭示CMT作为一个集成点作用于植物侧根中两个控制细胞各向异性生长分子机制的整合。

通讯：Charlotte Kirchhelle (https://www.plants.ox.ac.uk/people/dr-charlotte-kirchhelle)

个人简介：2006-2009年，慕尼黑工业大学，学士；2009-2012年，慕尼黑工业大学，硕士；2012-2016年，英国牛津大学，博士。

研究方向：植物侧根的形态建成；细胞几何结构的调控机制；膜运输。

doi: 10.7554/eLife.47988

Journal: eLife

Published date: July 29, 2019