Mechanical stress initiates and sustains the morphogenesis of wavy leaf epidermal cells
Plant cell morphogenesis is governed by the mechanical properties of the cell wall and the resulting cell shape is intimately related to the respective specific function. Pavement cells covering the surface of plant leaves form wavy interlocking patterns in many plants. We use computational mechanics to simulate the morphogenetic process based on experimentally assessed cell shapes, growth dynamics, and cell wall chemistry. The simulations and experimental evidence suggest a multistep process underlying the morphogenesis of pavement cells during tissue differentiation. The mechanical shaping process relies on spatially confined, feedback-augmented stiffening of the cell wall in the periclinal walls, an effect that correlates with experimentally observed deposition patterns of cellulose and de-esterified pectin. We provide evidence for mechanical buckling of the pavement cell walls that can robustly initiate patterns de novo and may precede chemical and geometrical anisotropy.\n\nHighlightsO_LIA multistep mechano-chemical morphogenetic process underlies the wavy pattern of epidermal pavement cells.\nC_LIO_LIMicrotubule polarization is preceded by an event that breaks mechanical isotropy in the cell wall.\nC_LIO_LIMechanical models simulate the formation of wavy cell shapes, predict buckling of the cell walls and spatially confined variations in the mechanical properties of leaf epidermal cells.\nC_LIO_LIStress/strain stiffening following the buckling of the cell walls constitutes a crucial element in a positive feedback loop forming interlocking pavement cells.\nC_LIO_LIPolarization of cortical microtubules, cellulose microfibrils, and de-esterified pectin occur at the necks of wavy pavement cells, matching the in silico prediction of cell wall stiffening.\nC_LI