Edge-based growth control in Arabidopsis involves two cell wall-associated Receptor-Like Proteins
Morphogenesis of multicellular organs requires coordination of cellular growth. In plants, 3D growth is driven by undirected turgor pressure, whereas growth directionality is controlled by cell wall mechanical properties at 2D cell faces. Their shared cell wall also fixes cells in their position, and plants thus have to integrate tissue-scale mechanical stresses arising due to growth in a fixed tissue topology. This implies a need to monitor cell wall mechanical and biochemical status and to adapt growth accordingly. Here, we propose that plant cells use their 1D cell edges to monitor cell wall status. We describe two Receptor-Like Proteins, RLP4 and RLP4-L1, which occupy a unique polarity domain at cell edges established through a targeted secretory transport pathway. We show that at cell edges, RLP4s associate with the cell wall via their extracellular domain, and contribute to directional growth control in Arabidopsis.