Poroelastic couplings in artificial and real plant tissues – ARTIS

Plants are able to perceive mechanical-stimuli and adapt their development to mechanical perturbations such as wind, rain or obstacles - a crucial issue in this period of rapid environmental changes. This project aims at investigating the role of fluid mechanics and mechanics in this complex response of plant to mechanical stresses. When a plant stem or branch is bent, a transient arrest of the growth is usually observed, not only locally but also far away from the stimulated area. This suggests the existence of a long distance information-signal within the plant network. The nature and mechanism of this long distance signal is not known, but it has been suggested recently that it could result from a purely hydraulic pressure signal in response to mechanical deformation, within the plant tissue seen as a soft porous media impregnated by a fluid.

The objective of the project is to investigate the coupling between mechanics and hydraulics in artificial and living plant tissues, and its role in plant mecano-perception and long distance signaling. Our approach is to design an original three-dimensional micro-fluidic device consisting of a transparent elastomer beam (PDMS) perforated with longitudinal micro-channels and filled with a viscous liquid. The poroelastic response of this biomimetic branch to a sudden bending will be studied in order to unveil the key physical ingredients and mechanisms at play. We anticipate that this physical system, although much simpler than the real plant tissue, contains the key ingredients needed to recover the phenomenology observed in plants. To this end, we will systematically compare the poroelastic response of the physical system with experiments performed on natural branches and stems, and add complexity in the physical system step-by-step. Our ultimate goal is to design an active soft poroelastic cellular media that mimics major physical processes found in plants, in order to explore new couplings with potential applications in micro-fluidic and soft robotics (coupling between mechanical deformation and cavitation, active motion induced by osmotic flows).

A notable aspect of our project lies in the interdisciplinary approach we propose, which combines experiments on both living and artificial tissues. This is made possible thanks to the complementarity backgrounds and skills in fluids mechanics, biomechanics and plant physiology of the member of our team shared between the laboratory IUSTI (CNRS/Aix-Marseille) and PIAF (INRA/Clermont-Ferrand). This project will also be the opportunity to develop novel approaches in our lab, from micro-fluidic and soft matter techniques to the development of biomimetic materials. This project should therefore help the emergence a young team, eager to develop new research themes at the crossroad of engineering, physics and biomechanics.