title: Actin-dependent vacuolar occupancy of the cell determines auxin-induced growth repression.
abstract: The cytoskeleton is an early attribute of cellular life, and its main components are composed of conserved proteins. The actin cytoskeleton has a direct impact on the control of cell size in animal cells, but its mechanistic contribution to cellular growth in plants remains largely elusive. Here, we reveal a role of actin in regulating cell size in plants. The actin cytoskeleton shows proximity to vacuoles, and the phytohormone auxin not only controls the organization of actin filaments but also impacts vacuolar morphogenesis in an actin-dependent manner. Pharmacological and genetic interference with the actin-myosin system abolishes the effect of auxin on vacuoles and thus disrupts its negative influence on cellular growth. SEM-based 3D nanometer-resolution imaging of the vacuoles revealed that auxin controls the constriction and luminal size of the vacuole. We show that this actin-dependent mechanism controls the relative vacuolar occupancy of the cell, thus suggesting an unanticipated mechanism for cytosol homeostasis during cellular growth.
authors.affiliation: Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, 1190 Vienna, Austria;
authors.forename: David
authors.initials: D
authors.lastname: Scheuring
authors.affiliation: Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, 1190 Vienna, Austria;
authors.forename: Christian
authors.initials: C
authors.lastname: Löfke
authors.affiliation: Center for Organismal Studies, University of Heidelberg, 69120 Heidelberg, Germany;
authors.forename: Falco
authors.initials: F
authors.lastname: Krüger
authors.affiliation: Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, United Kingdom;
authors.forename: Maike
authors.initials: M
authors.lastname: Kittelmann
authors.affiliation: Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, 1190 Vienna, Austria;
authors.forename: Ahmed
authors.initials: A
authors.lastname: Eisa
authors.affiliation: Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, United Kingdom;
authors.forename: Louise
authors.initials: L
authors.lastname: Hughes
authors.affiliation: Department of Comparative Development and Genetics, Max Planck Institute for Plant Breeding Research, 50829 Cologne, Germany.
authors.forename: Richard S
authors.initials: RS
authors.lastname: Smith
authors.affiliation: Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, United Kingdom;
authors.forename: Chris
authors.initials: C
authors.lastname: Hawes
authors.affiliation: Center for Organismal Studies, University of Heidelberg, 69120 Heidelberg, Germany;
authors.forename: Karin
authors.initials: K
authors.lastname: Schumacher
authors.affiliation: Department of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, 1190 Vienna, Austria; juergen.kleine-vehn@boku.ac.at.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Kleine-Vehn
mesh_terms: D008841:Actin Cytoskeleton / Q000187:drug effects / Q000378:metabolism; D000199:Actins / Q000378:metabolism*; D017360:Arabidopsis / Q000166:cytology* / Q000187:drug effects / Q000254:growth & development*; D021621:Imaging, Three-Dimensional; D007210:Indoleacetic Acids / Q000494:pharmacology*; D007425:Intracellular Membranes / Q000187:drug effects / Q000378:metabolism; D018519:Meristem / Q000187:drug effects; D008870:Microtubules / Q000187:drug effects / Q000378:metabolism; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics; D009218:Myosins / Q000378:metabolism; D010716:Phosphatidylinositols / Q000378:metabolism; D018517:Plant Roots / Q000166:cytology / Q000187:drug effects; D055550:Protein Stability / Q000187:drug effects; D014617:Vacuoles / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D000199:Actins; D007210:Indoleacetic Acids; D010716:Phosphatidylinositols; D009218:Myosins
keywords: actin cytoskeleton; auxin; cell growth; vacuole