title: The Arabidopsis exocyst complex is involved in cytokinesis and cell plate maturation.
abstract: Cell reproduction is a complex process involving whole cell structures and machineries in space and time, resulting in regulated distribution of endomembranes, organelles, and genomes between daughter cells. Secretory pathways supported by the activity of the Golgi apparatus play a crucial role in cytokinesis in plants. From the onset of phragmoplast initiation to the maturation of the cell plate, delivery of secretory vesicles is necessary to sustain successful daughter cell separation. Tethering of secretory vesicles at the plasma membrane is mediated by the evolutionarily conserved octameric exocyst complex. Using proteomic and cytologic approaches, we show that EXO84b is a subunit of the plant exocyst. Arabidopsis thaliana mutants for EXO84b are severely dwarfed and have compromised leaf epidermal cell and guard cell division. During cytokinesis, green fluorescent protein-tagged exocyst subunits SEC6, SEC8, SEC15b, EXO70A1, and EXO84b exhibit distinctive localization maxima at cell plate initiation and cell plate maturation, stages with a high demand for vesicle fusion. Finally, we present data indicating a defect in cell plate assembly in the exo70A1 mutant. We conclude that the exocyst complex is involved in secretory processes during cytokinesis in Arabidopsis cells, notably in cell plate initiation, cell plate maturation, and formation of new primary cell wall.
authors.affiliation: Institute of Experimental Botany, Academy of Sciences of the Czech Republic, 165 02 Prague 6, Czech Republic.
authors.forename: Matyás
authors.initials: M
authors.lastname: Fendrych
authors.forename: Lukás
authors.initials: L
authors.lastname: Synek
authors.forename: Tamara
authors.initials: T
authors.lastname: Pecenková
authors.forename: Hana
authors.initials: H
authors.lastname: Toupalová
authors.forename: Rex
authors.initials: R
authors.lastname: Cole
authors.forename: Edita
authors.initials: E
authors.lastname: Drdová
authors.forename: Jana
authors.initials: J
authors.lastname: Nebesárová
authors.forename: Miroslava
authors.initials: M
authors.lastname: Sedinová
authors.forename: Michal
authors.initials: M
authors.lastname: Hála
authors.forename: John E
authors.initials: JE
authors.lastname: Fowler
authors.forename: Viktor
authors.initials: V
authors.lastname: Zársky
mesh_terms: D017360:Arabidopsis / Q000166:cytology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism; D048749:Cytokinesis; D016254:Mutagenesis, Insertional; D009154:Mutation; D040901:Proteomics; D033921:Vesicular Transport Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D033921:Vesicular Transport Proteins