Force-Driven Polymerization and Turgor-Induced Wall Expansion

While many molecular players involved in growth control have been identified in the past decades, it is often unknown how they mechanistically act to induce specific shape changes during development. Plant morphogenesis results from the turgor-induced yielding of the extracellular and load-bearing cell wall. Its mechanochemical equilibrium appears as a fundamental link between molecular growth regulation and the effective shape evolution of the tissue. We focus here on force-driven polymerization of the cell wall as a central process in growth control. We propose that mechanical forces facilitate the insertion of wall components, in particular pectins, a process that can be modulated through genetic regulation. We formalize this idea in a mathematical model, which we subsequently test with published experimental results.

TrendsCellulose microfibrils have historically been the focus of most biomechanical studies of the cell wall. Recent results, however, suggest that the soft pectin matrix in which they are embedded might also play a significant role in the physicochemical equilibrium of growing cells.At the molecular scale, biophysicists have shown how mechanical forces applied on molecular assemblies can modulate their chemical state and therefore initiate specific biological responses.At the tissue scale, numerical simulation tools borrowed from material sciences are increasingly being used in developmental biology. Morphogenesis in plant tissues is particularly suited to this type of approach.Bridging the gap between the molecular and the tissue scales is a major challenge in developmental biology because it would help to relate shape changes explicitly to specific molecular players.