title: Mechanical Stress Induces Remodeling of Vascular Networks in Growing Leaves.
abstract: Differentiation into well-defined patterns and tissue growth are recognized as key processes in organismal development. However, it is unclear whether patterns are passively, homogeneously dilated by growth or whether they remodel during tissue expansion. Leaf vascular networks are well-fitted to investigate this issue, since leaves are approximately two-dimensional and grow manyfold in size. Here we study experimentally and computationally how vein patterns affect growth. We first model the growing vasculature as a network of viscoelastic rods and consider its response to external mechanical stress. We use the so-called texture tensor to quantify the local network geometry and reveal that growth is heterogeneous, resembling non-affine deformations in composite materials. We then apply mechanical forces to growing leaves after veins have differentiated, which respond by anisotropic growth and reorientation of the network in the direction of external stress. External mechanical stress appears to make growth more homogeneous, in contrast with the model with viscoelastic rods. However, we reconcile the model with experimental data by incorporating randomness in rod thickness and a threshold in the rod growth law, making the rods viscoelastoplastic. Altogether, we show that the higher stiffness of veins leads to their reorientation along external forces, along with a reduction in growth heterogeneity. This process may lead to the reinforcement of leaves against mechanical stress. More generally, our work contributes to a framework whereby growth and patterns are coordinated through the differences in mechanical properties between cell types.
authors.affiliation: Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel.|Racah Institute of Physics, The Hebrew University, Jerusalem, Israel.|Laboratoire de Physique Statistique, Ecole Normale Supérieure, CNRS, Université Paris VI, Université Paris VII, Paris, France.
authors.forename: Yohai
authors.initials: Y
authors.lastname: Bar-Sinai
authors.affiliation: Laboratoire de Physique, ENS Lyon, CNRS, UCB Lyon I, Université de Lyon, Lyon, France.|Laboratoire Reproduction et Développement des Plantes, Univ Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, Lyon, France.|Laboratoire Joliot-Curie, Univ Lyon, ENS de Lyon, CNRS, Lyon, France.
authors.forename: Jean-Daniel
authors.initials: JD
authors.lastname: Julien
authors.affiliation: Racah Institute of Physics, The Hebrew University, Jerusalem, Israel.
authors.forename: Eran
authors.initials: E
authors.lastname: Sharon
authors.affiliation: Racah Institute of Physics, The Hebrew University, Jerusalem, Israel.
authors.forename: Shahaf
authors.initials: S
authors.lastname: Armon
authors.affiliation: Institute of Molecular Plant Sciences, University of Edinburgh, Edinburgh, United Kingdom.
authors.forename: Naomi
authors.initials: N
authors.lastname: Nakayama
authors.affiliation: Laboratoire de Physique Statistique, Ecole Normale Supérieure, CNRS, Université Paris VI, Université Paris VII, Paris, France.
authors.forename: Mokhtar
authors.initials: M
authors.lastname: Adda-Bedia
authors.affiliation: Laboratoire Reproduction et Développement des Plantes, Univ Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, Lyon, France.|Laboratoire Joliot-Curie, Univ Lyon, ENS de Lyon, CNRS, Lyon, France.|Institut Universitaire de France, Paris, France.
authors.forename: Arezki
authors.initials: A
authors.lastname: Boudaoud
mesh_terms: D016880:Anisotropy; D017360:Arabidopsis / Q000254:growth & development; D001696:Biomechanical Phenomena; D019521:Body Patterning; D019295:Computational Biology; D003198:Computer Simulation; D008954:Models, Biological; D018515:Plant Leaves / Q000254:growth & development*; D058526:Plant Vascular Bundle / Q000254:growth & development*; D013314:Stress, Mechanical