Plant morphology emerges from cellular growth. The turgor-driven diffuse growth of a cell can be highly anisotropic: significant in the longitudinal direction and negligible in the radial direction. This anisotropy arises from cellulose microfibrils (CMF) reinforcing the cell wall. To maintain the cell’s integrity during growth, new material including CMF must be continually deposited into the cell wall. In this talk, I will present a mathematical model which describes the cell as a pressurised cylindrical vessel and the cell wall as a fibre-reinforced viscous sheet, explicitly including the mechano-sensitive angle of CMF deposition. The model incorporates interactions between turgor, external forces, CMF reorientation during wall extension, and matrix stiffening. I will explain the general formulation of the model and summarise the technical steps towards obtaining evolution equations for the cell’s length and twist. A generalised Lockhart equation will be derived. I will discuss how the handedness of twisting cell growth depends on external torque and intrinsic wall properties, and interpret numerical results in light of recent experimental findings. Overall, the model provides a meaningful step towards a unified mechanical framework for understanding left- and right-handed growth as seen in many plants.
This video was produced by the Biologically Active Fluids special interest group, as part of their seminar series.
