title: The development and geometry of shape change in Arabidopsis thaliana cotyledon pavement cells.
abstract: BACKGROUND
  The leaf epidermis is an important architectural control element that influences the growth properties of underlying tissues and the overall form of the organ. In dicots, interdigitated pavement cells are the building blocks of the tissue, and their morphogenesis includes the assembly of specialized cell walls that surround the apical, basal, and lateral (anticlinal) cell surfaces. The microtubule and actin cytoskeletons are highly polarized along the cortex of the anticlinal wall; however, the relationships between these arrays and cell morphogenesis are unclear.
  
  
  RESULTS
  We developed new quantitative tools to compare population-level growth statistics with time-lapse imaging of cotyledon pavement cells in an intact tissue. The analysis revealed alternating waves of lobe initiation and a phase of lateral isotropic expansion that persisted for days. During lateral isotropic diffuse growth, microtubule organization varied greatly between cell surfaces. Parallel microtubule bundles were distributed unevenly along the anticlinal surface, with subsets marking stable cortical domains at cell indentations and others clearly populating the cortex within convex cell protrusions.
  
  
  CONCLUSIONS
  Pavement cell morphogenesis is discontinuous, and includes punctuated phases of lobe initiation and lateral isotropic expansion. In the epidermis, lateral isotropic growth is independent of pavement cell size and shape. Cortical microtubules along the upper cell surface and stable cortical patches of anticlinal microtubules may coordinate the growth behaviors of orthogonal cell walls. This work illustrates the importance of directly linking protein localization data to the growth behavior of leaf epidermal cells.
authors.affiliation: Department of Agronomy, Purdue University, West Lafayette, Indiana 47907-2054, USA.
authors.forename: Chunhua
authors.initials: C
authors.lastname: Zhang
authors.forename: Leah E
authors.initials: LE
authors.lastname: Halsey
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Szymanski
mesh_terms: D017360:Arabidopsis / Q000033:anatomy & histology* / Q000166:cytology*; D048430:Cell Shape; D018548:Cotyledon / Q000033:anatomy & histology* / Q000166:cytology*; D018525:Germination; D049452:Green Fluorescent Proteins / Q000378:metabolism; D016014:Linear Models; D008870:Microtubules / Q000378:metabolism; D019441:Plant Epidermis / Q000166:cytology / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013997:Time Factors; D059008:Time-Lapse Imaging
chemical_list: D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins