Emergence of helical growth and morphogenesis in fungal cells from cell wall dynamics*

Walled cells such as plants, algae and fungi achieve expansive growth using turgor pressure that helps mediate irreversible wall deformation and regulates their shape and volume. The architecture of the cell wall plays a crucial role in this process where a network of microfibrils and tethers (complex polysaccharides and proteins) dynamically mediate the network topology via continuous detachment and reattachment events. The growth of Phycomyces blakesleeanus, a wiry single-celled sporangiophore that typically grows longitudinally, is particularly intriguing as it also rotates (clockwise from top) indicating helical growth. There is no apparent functional purpose for this rotation which has led to speculation that it is a direct consequence of wall architecture, and specifically a microfibril re-orientation mechanism. Interestingly, in piloboloid mutants longitudinal growth is combined with radial growth to produce a rotation inversion, i.e. anti-clockwise rotation. In this talk, we will present a novel approach based in statistical mechanics to model the organization and dynamics of microfibrils and tethers in the cell wall of to help explain this phenomenon.