Role of the CLE40-ACR4 signalling module in Arabidopsis root development

植物根系的生长受分生组织的控制，分生组织不断产生新的细胞。这些细胞后来专门从事各自的任务，如营养吸收、水运输或保护生长的根尖。拟南芥的根由排列成规则的细胞文件的细胞组成，这些细胞起源于根尖的干细胞。干细胞的分裂活性及其子细胞的分化必须协调，这是通过植物激素生长素和小肽等信号的交换来实现的。CLE40肽由分化的小柱细胞分泌。它由小柱干细胞质膜上的受体蛋白ACR4感知，并控制转录因子WOX5的表达。反过来，需要WOX5来抑制小柱干细胞过早分化。CLE40、ACR4和WOX5共同建立了一个调控模块，控制根分生组织中的细胞行为。我们打算分析这个模块的组成部分是如何相互作用的，它们与生长素信号通路的交集，以及由这个模块调节的目标基因，并最终控制细胞进一步分裂或分化的决定。为了了解CLE40-ACR4-WOX5模块的功能，我们将改变单个组件的活性，研究它们的相互转录调控，并研究它们的启动子中的转录控制区域。激素信号通路的输入将通过激素治疗或激素功能和运输的抑制来研究。目标基因及其活性将通过下一代测序方法和适当突变系的产生来确定。

The growth of plant roots is controlled by meristems that constantly generate new cells. These cells later specialize for their individual tasks, such as nutrient uptake, water transport, or protection of the growing root tip. The Arabidopsis root consists of cells arranged in regular cell files, which originate from stem cells at the root tip. Divisional activity of stem cells and differentiation of their daughter cells has to be coordinated, which is achieved through the exchange of signals such as the phytohormone auxin and small peptides. The peptide CLE40 is secreted by differentiated columella cells. It is perceived by the receptor protein ACR4 that resides on the plasma membrane of columella stem cells and controls expression of the transcription factor WOX5. WOX5 is in turn required to inhibit the columella stem cells from premature differentiation. Together, CLE40, ACR4 and WOX5 establish a regulatory module that controls cell behavior in the root meristem. We intend to analyse how the components of this module interact, their intersection with auxin signaling pathways, and the target genes that are regulated by this module and ultimately control a cells decision to further divide or differentiate. To understand the functioning of the CLE40-ACR4-WOX5 module, we will change the activity of the individual components, study their mutual transcription regulation, and investigate transcriptional control regions in their promoters. Input from hormone signalling pathways will be investigated by hormone treatments or inhibiton of hormone function and transport. Target genes and their activity will be identified by next-generation sequencing approaches, and by the generation of appropriate mutant lines.