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

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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.