Cell shape formation through material heterogeneity in the plant cell wall

Plant cells come in a kaleidoscopic variety of shapes that are intimately tied to their respective functions. The growth and shaping of plant cells involve the deformation of the cell envelope driven by the internal hydrostatic pressure. While the morphogenetic process is known to be influenced by cellulose microfibril reinforcements in the cell wall, a detailed understanding of the underlying mechanical principles is elusive. We discovered that in complex cell shapes, spatial heterogeneity in the cell wall mechanical properties is tightly controlled and relies on local enrichment in pectin and strategically deposited microfibrils. Through high resolution fluorescence imaging, we correlated the presence of these polysaccharides in space and time with morphogenetic events. The experimental observations confirm predictions made by a finite element modeling approach developed to simulate plant cell shaping. A computational model of the jigsaw puzzle shaped cell patterns in the leaf epidermis also revealed that symmetry breaking events in the cell morphogenetic process might be initiated through turgor-driven buckling events. The mechanical modeling approach has led to a multitude of predictions guiding experimentalists towards biological agents with morphogenetic roles.