Epidermal Cell Lobe Formation Occurs via Cell Wall Wrinkling

Specialized cell geometries in the plant epidermis optimize important biochemical and mechanical functions. For example, epidermal pavement cells, which maintain the mechanical stability of leaves and petals, develop from convex, smooth-polygonal cells to highly lobed "puzzle-piece-shaped" cells. While these lobed cells are observed across many species, the physical mechanism behind lobe formation is not fully understood. We propose a novel computational model for epidermal cell development where lobes emerge due to a wrinkling instability in the cell wall. We find that the lobe wavelength is controlled by mechanical properties of the cell wall, as linear stability analysis predicts. Our model also incorporates stomatal complexes, which have different physical properties and thus do not wrinkle. We validate the results of our model against light microscopy images of the epidermis during development.