ABSTRACT
How the development of complex multicellular organisms is accomplished through coordinated cell proliferation, differentiation, and growth is a fundamental biological question. In plants, the relative position of neighbouring cells is fixed as they share a rigid extracellular matrix, the cell wall. The cell wall is deployed in oriented fashion during cytokinesis and is known to guide morphogenesis through localised allowance and selective restriction of cell expansion. It has recently become clear that plant cells sense cell wall state and integrate this information with other pathways to adjust cellular behaviour. Thus, the physical and chemical properties of the cell wall are assumed to be under constant surveillance by cell surface receptors, which are directly connected to intracellular signalling. Here, we provide an overview of current knowledge on cell wall signalling pathways and their diverse roles in development, stress response, defence, and cell wall integrity maintenance and highlight open questions in this vibrant and dynamic field.
