title: Symmetry breaking in spore germination relies on an interplay between polar cap stability and spore wall mechanics.
abstract: The morphogenesis of single cells depends on their ability to coordinate surface mechanics and polarity. During germination, spores of many species develop a polar tube that hatches out of a rigid outer spore wall (OSW) in a process termed outgrowth. However, how these awakening cells reorganize to stabilize this first growth axis remains unknown. Here, using quantitative experiments and modeling, we reveal the mechanisms underlying outgrowth in fission yeast. We find that, following an isotropic growth phase during which a single polarity cap wanders around the surface, outgrowth occurs when spores have doubled their volume, concomitantly with the stabilization of the cap and a singular rupture in the OSW. This rupture happens when OSW mechanical stress exceeds a threshold, releases the constraints of the OSW on growth, and stabilizes polarity. Thus, outgrowth exemplifies a self-organizing morphogenetic process in which reinforcements between growth and polarity coordinate mechanics and internal organization.
authors.affiliation: Institut Jacques Monod, 15 rue Hélène Brion, 75205 Paris Cedex 13, France; Institut Curie, UMR 144 CNRS/IC, 26 rue d'Ulm, 75248 Paris Cedex 05, France.
authors.forename: Daria
authors.initials: D
authors.lastname: Bonazzi
authors.affiliation: Laboratoire Joliot-Curie, CNRS, ENS de Lyon, Université de Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France; Laboratoire de Physique, CNRS, ENS de Lyon, UCBL Lyon I, 46 Allée d'Italie, 69364 Lyon Cedex 07, France; Reproduction et Développement des Plantes, INRA, CNRS, ENS de Lyon, UCBL Lyon I, 46 Allée d'Italie, 69364 Lyon Cedex 07, France.
authors.forename: Jean-Daniel
authors.initials: JD
authors.lastname: Julien
authors.affiliation: Institut Curie, UMR 144 CNRS/IC, 26 rue d'Ulm, 75248 Paris Cedex 05, France.
authors.forename: Maryse
authors.initials: M
authors.lastname: Romao
authors.affiliation: Institut Jacques Monod, 15 rue Hélène Brion, 75205 Paris Cedex 13, France.
authors.forename: Rima
authors.initials: R
authors.lastname: Seddiki
authors.affiliation: Institut Curie, UMR 144 CNRS/IC, 26 rue d'Ulm, 75248 Paris Cedex 05, France.
authors.forename: Matthieu
authors.initials: M
authors.lastname: Piel
authors.affiliation: Laboratoire Joliot-Curie, CNRS, ENS de Lyon, Université de Lyon, 46 Allée d'Italie, 69364 Lyon Cedex 07, France; Reproduction et Développement des Plantes, INRA, CNRS, ENS de Lyon, UCBL Lyon I, 46 Allée d'Italie, 69364 Lyon Cedex 07, France. Electronic address: arezki.boudaoud@ens-lyon.fr.
authors.forename: Arezki
authors.initials: A
authors.lastname: Boudaoud
authors.affiliation: Institut Jacques Monod, 15 rue Hélène Brion, 75205 Paris Cedex 13, France. Electronic address: minc@ijm.univ-paris-diderot.fr.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Minc
mesh_terms: D049108:Cell Enlargement; D016764:Cell Polarity / Q000502:physiology*; D002473:Cell Wall / Q000502:physiology*; D007091:Image Processing, Computer-Assisted; D040542:Mechanotransduction, Cellular / Q000502:physiology*; D009024:Morphogenesis / Q000502:physiology*; D012568:Schizosaccharomyces / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000378:metabolism; D013172:Spores, Fungal / Q000254:growth & development* / Q000378:metabolism; D059008:Time-Lapse Imaging
chemical_list: D029702:Schizosaccharomyces pombe Proteins