title: The impact of mechanical compression on cortical microtubules in Arabidopsis: a quantitative pipeline.
abstract: Exogenous mechanical perturbations on living tissues are commonly used to investigate whether cell effectors can respond to mechanical cues. However, in most of these experiments, the applied mechanical stress and/or the biological response are described only qualitatively. We developed a quantitative pipeline based on microindentation and image analysis to investigate the impact of a controlled and prolonged compression on microtubule behaviour in the Arabidopsis shoot apical meristem, using microtubule fluorescent marker lines. We found that a compressive stress, in the order of magnitude of turgor pressure, induced apparent microtubule bundling. Importantly, that response could be reversed several hours after the release of compression. Next, we tested the contribution of microtubule severing to compression-induced bundling: microtubule bundling seemed less pronounced in the katanin mutant, in which microtubule severing is dramatically reduced. Conversely, some microtubule bundles could still be observed 16 h after the release of compression in the spiral2 mutant, in which severing rate is instead increased. To quantify the impact of mechanical stress on anisotropy and orientation of microtubule arrays, we used the nematic tensor based FibrilTool ImageJ/Fiji plugin. To assess the degree of apparent bundling of the network, we developed several methods, some of which were borrowed from geostatistics. The final microtubule bundling response could notably be related to tissue growth velocity that was recorded by the indenter during compression. Because both input and output are quantified, this pipeline is an initial step towards correlating more precisely the cytoskeleton response to mechanical stress in living tissues.
authors.affiliation: Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, F-69342, Lyon, France.|Laboratoire Joliot-Curie, CNRS, ENS de Lyon, UCB Lyon 1, Université de Lyon, 46 allée d'Italie, 69364, Lyon Cedex 07, France.
authors.forename: Marion
authors.initials: M
authors.lastname: Louveaux
authors.affiliation: Département Dynamiques de l'Environnement Côtier, Laboratoire d'Écologie Benthique Côtière (LEBCO), Ifremer, CS 10070, 29280, Plouzané, France.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Rochette
authors.affiliation: Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, F-69342, Lyon, France.|Laboratoire Joliot-Curie, CNRS, ENS de Lyon, UCB Lyon 1, Université de Lyon, 46 allée d'Italie, 69364, Lyon Cedex 07, France.
authors.forename: Léna
authors.initials: L
authors.lastname: Beauzamy
authors.affiliation: Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, F-69342, Lyon, France.|Laboratoire Joliot-Curie, CNRS, ENS de Lyon, UCB Lyon 1, Université de Lyon, 46 allée d'Italie, 69364, Lyon Cedex 07, France.
authors.forename: Arezki
authors.initials: A
authors.lastname: Boudaoud
authors.affiliation: Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRA, F-69342, Lyon, France.|Laboratoire Joliot-Curie, CNRS, ENS de Lyon, UCB Lyon 1, Université de Lyon, 46 allée d'Italie, 69364, Lyon Cedex 07, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Hamant
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D000074201:Katanin; D018519:Meristem / Q000235:genetics / Q000378:metabolism; D008870:Microtubules / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D013314:Stress, Mechanical
chemical_list: D029681:Arabidopsis Proteins; D000251:Adenosine Triphosphatases; D000074201:Katanin
keywords: 
  Arabidopsis thaliana
  ; bundling; compression; indenter; mechanical stress; microtubules; technical advance