Decoding how signalling from the plant cell wall controls cell fate decisions in the shoot apical meristem

植物的一个决定性特征，是由无根生活方式强加的，是它们对环境的显著发育可塑性。这种可塑性的基础是持续活跃的多能干细胞，它们为新器官的终身胚胎后形成提供燃料。由于植物细胞被包裹在细胞壁中，因此是不动的，它们的个体命运规范程序强烈地依赖于它们在生物体中的相对位置。此外，植物的生长在很大程度上依赖于细胞壁重塑介导的细胞扩增，强调细胞壁是植物形态发生的主要决定因素。假设细胞壁的状态受到细胞表面受体的持续监视，直接将细胞壁状态与细胞内基因调控网络联系起来。然而，这些细胞壁信号通路在植物发育中的作用以及细胞壁特性和机制对细胞行为和细胞身份的贡献尚不清楚。我们之前的研究结果表明，细胞壁信号成分参与细胞身份的维持，细胞壁特性的控制对干细胞群体的延续和器官发生至关重要。这些结果表明植物细胞壁不仅参与细胞分化，而且还反馈发育转变，为研究直接物理环境如何能够指导植物细胞命运决定铺平了道路。因此，在提出的研究框架中，我们的目标是破译细胞壁信号如何控制模式植物拟南芥的细胞身份。为此，我们将研究干细胞中细胞壁特性是如何被控制的，并揭示细胞壁信号如何影响特定细胞类型的转录特征。此外，我们将评估细胞壁信号如何与茎尖分生组织模式的已知调节因子相交，并识别细胞壁触发信号转导的分子成分。

A defining feature of plants, imposed by a sessile lifestyle, is their remarkable developmental plasticity in response to the environment. At the basis of this plasticity are continuously active pluripotent stem cells, which fuel the life-long post-embryonic formation of new organs. Since plant cells are encased in cell walls and thus immotile, their individual fate-specification program is strongly dependent on the relative position within the organism. In addition, plant growth to a large extent relies on cell expansion mediated by cell wall remodelling, highlighting the cell wall as a major determinant of plant morphogenesis. It is assumed that the state of the cell wall is under constant surveillance by cell surface receptors directly linking cell wall state to intracellular gene-regulatory networks. However, the role of these cell wall signalling pathways in plant development and the contribution of cell wall properties and mechanics to cell behaviour and cell identity are not well understood. Our previous results demonstrate that cell wall signalling components are involved in maintenance of cell identity and that control of cell wall properties is essential for the perpetuation of stem cell populations and organogenesis. These results point to a scenario in which the plant cell wall is not only involved in cell differentiation, but also feeds back on developmental transitions, paving the way to study how the immediate physical environment is able to guide cell fate decisions in plants. In the framework of the proposed research, we therefore aim to decipher how cell wall signalling controls cell identity in the model plant Arabidopsis thaliana. To this end, we will study how cell wall properties are controlled in stem cells and unravel how signals from the cell wall affect the transcriptional signatures of specific cell types. Moreover, we will assess how cell wall signalling intersects with known regulators of shoot apical meristem patterning and identify molecular components of cell wall-triggered signal transduction.