Speaker
Description
Twisted shapes in plants, seen in helical roots, spiral grains and climbing vines, are both ubiquitous and consequential. They affect crop yield, impact lumber quality, and inspire biomimetic robotics. Understanding their mechanical origins begins at the single-cell level. The cell wall is a complex material: a pectin matrix reinforced by cellulose microfibrils that dynamically reorient during deformation. Under constant turgor pressure, anisotropic wall extension drives growth. We combine theories of transversely isotropic fluids, pressure-driven viscous sheets, and dynamic fibre-reorientation, developing a model for helical cell wall extension. The talk will present the model and semi-analytical solutions, including recent results on an internalised control mechanism for the growth and twist rates, and a generalised Lockhart equation that relates cell morphology to cellulose dynamics. This framework provides a key step towards explaining and controlling twisting morphology at the tissue and organ scales, which in turn underpins food security, sustainable development, and bio-inspired design.
