Growing in a wave—physical mechanisms of hypocotyl growth
My research group studies how cell wall mechanics, in plants and algae, regulates growth and development; from understanding single cell shape generation to examining cell adhesion and coordination to interpreting the mechanisms of whole organism motion. We utilise approaches from biology, mathematics, biochemistry, and materials science to understand the dynamic nature of the cell wall.
As one of the first events in a plant’s life, hypocotyl elongation is a critical growth phenomenon. We have been working towards a physical understanding of 1) 2D hypocotyl elongation in the dark, which results from an acropetal wave of anisotropic cell elongation, and 2) 3D movements associated with hypocotyl elongation, described by Darwin as circumnutation. Our work has focused recently on the kinematic and geometrical analysis of growth and motion alongside a mechanical understanding of cell wall biochemistry and mechanical properties. We have recently developed an understanding of how cell wall pectin chemistry affects wall mechanics, organ growth, and anisotropy – with respect to the wave of growth exhibited in 2D. To study circumnutation in a brand new way, we have developed a stereographic imaging system which allows us to characterise a whole seedling’s geometry during motion, yielding an interesting insight: the wide number of possible geometries for the seedling appear to be limited by its physical structure.