Xyloglucans and microtubules synergistically maintain meristem geometry and phyllotaxis

First author: Feng Zhao; Affiliations: INRA (法国国家农业科学研究院): Lyon, France

Corresponding author: Jan Traas

The shoot apical meristem (SAM) gives rise to all aerial plant organs. Cell walls are thought to play a central role in this process, translating molecular regulation into dynamic changes in growth rate and direction, although their precise role in morphogenesis during organ formation is poorly understood. Here, we investigated the role of xyloglucans (XyGs), a major, yet functionally poorly characterized, wall component in the SAM of Arabidopsis thaliana. Using immunolabeling, biochemical analysis, genetic approaches, micro-indentation, laser ablation, and live imaging, we showed that XyGs are important for meristem shape and phyllotaxis. No difference in the Young's modulus (i.e. an indicator of wall stiffness) of the cell walls was observed when XyGs were perturbed. Mutations in enzymes required for XyG synthesis also affect other cell wall components such as cellulose content and pectin methylation status. Interestingly, control of cortical microtubule dynamics by the severing enzyme KATANIN became vital when XyGs were perturbed or absent. This suggests that the cytoskeleton plays an active role in compensating for altered cell wall composition.

茎尖分生组织是植物所有地上部分器官的来源。细胞壁在该过程中发挥着重要作用，将分子调控转化成为生长速率和方向的动态变化，但其在器官形成时形态发生方面具体的调控机制还不是很清楚。本文中，作者研究了一个细胞壁主要成份但功能研究得还不是很清楚的木葡聚糖XyGs在拟南芥茎尖分生组织中的作用。利用免疫标记、生化分析、遗传试验、显微压痕、激光烧蚀以及实时成像，作者的研究显示XyGs对于分生组织形状以及叶序非常重要。当XyGs被扰动后，细胞壁的硬度指标杨氏模量并不会出现明显的差异。XyG合成相关酶的突变同样能够影响到其他的细胞壁组分，比如纤维素含量和果胶甲基化状态。有趣的是，当XyGs被干扰或缺失时，通过中断KATANIN酶调控皮质微管动态变得至关重要。这说明细胞骨架在补偿细胞壁组分改变时发挥重要作用。

通讯：Jan Traas  (http://jobs.inra.fr/en/Career-opportunities/Portraits/jan-traas2)

个人简介：1982-1987年，荷兰奈梅根大学，博士；英国诺维奇约翰英纳斯研究所，博士后。

研究方向：植物在细胞水平的生长方向和速度。

doi: https://doi.org/10.1104/pp.19.00608

Journal: Plant Physiology

First Published: September 20, 2019