Understanding how water flows through the root is of major importance to understand (and improve) how plants sense and adapt to their environment. The capacity of plant roots to take up water is determined by their architecture and the hydraulic properties of root cells and tissues. These characteristics determine the surface of the root system, and its intrinsic permeability to water, respectively.

We have been developing a "multi-tree graph"-based model of the root system, which allows us to dissect the influence of architecture, radial and axial hydraulic conductivities on the overall water flow in the Arabidopsis root. Contribution of apoplastic and cell-to-cell pathways to the radial flow is being addressed by a partial differential equation approach. Ultimately, the goal is to build a root hydraulic model able to predict the behavior of the organ in various genotypes and environmental conditions. Feeding the models with biological (and realistic) parameters is a challenge towards this goal. The latest results and the interplay between experimental and modeling approaches will be presented.