Chalmers Conferences, 9th European Conference on Mathematical and Theoretical Biology

Computational Modelling of Planar Cell Polarity in the Arabidopsis Root Epidermis
Bettina Greese, Markus Grebe, Henrik Jönsson

Last modified: 2014-06-09


We study the mechanisms underlying the establishment of root hair placement in the model plant Arabidopsis thaliana, which is an indicator of coordinated cell polarity within the plane of the root epidermis (planar polarity). Our cell-based computational model integrates the formation of the auxin concentration gradient in the root with the intracellular dynamics of Rho-of-plant (ROP) GTPases, which control root hair outgrowth.

The phytohormone auxin is transported by several membrane-bound proteins, some of which are restricted to specific sides of cells. Incorporating this into our model, we obtain a realistic auxin gradient that decreases away from the root tip. It is known that auxin enhances root hair growth. We assume that auxin activates ROPs by catalysing their recruitment to the membrane, where they trigger hair formation. Our simulations show homogeneous concentrations of active ROPs in cells near the root tip and peaks in cells further away. This onset of ROP polarity agrees with observations and is shifted by various perturbations - in experiments and simulations.

We explore the importance of specific tissue architecture, transport protein localisation, and parameter values in order to understand the establishment of cell polarity as part of the signalling machinery during plant morphogenesis.