title: Unstable F-actin specifies the area and microtubule direction of cell expansion in Arabidopsis root hairs.
abstract: Plant cells expand by exocytosis of wall material contained in Golgi-derived vesicles. We examined the role of local instability of the actin cytoskeleton in specifying the exocytosis site in Arabidopsis root hairs. During root hair growth, a specific actin cytoskeleton configuration is present in the cell's subapex, which consists of fine bundles of actin filaments that become more and more fine toward the apex, where they may be absent. Pulse application of low concentrations of the actin-depolymerizing drugs cytochalasin D and latrunculin A broadened growing root hair tips (i.e., they increased the area of cell expansion). Interestingly, recovery from cytochalasin D led to new growth in the original growth direction, whereas in the presence of oryzalin, a microtubule-depolymerizing drug, this direction was altered. Oryzalin alone, at the same concentration, had no influence on root hair elongation. These results represent an important step toward understanding the spatial and directional regulation of root hair growth.
authors.affiliation: Laboratory of Plant Cell Biology, Department of Plant Sciences, Wageningen University, Arboretumlaan 4, 6703 BD Wageningen, The Netherlands.
authors.forename: Tijs
authors.initials: T
authors.lastname: Ketelaar
authors.forename: Norbert C A
authors.initials: NC
authors.lastname: de Ruijter
authors.forename: Anne Mie C
authors.initials: AM
authors.lastname: Emons
mesh_terms: D000199:Actins / Q000378:metabolism*; D017360:Arabidopsis / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D002455:Cell Division / Q000502:physiology; D015638:Cytochalasin D / Q000494:pharmacology; D003599:Cytoskeleton / Q000502:physiology; D004136:Dinitrobenzenes / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D008870:Microtubules / Q000502:physiology*; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism; D013424:Sulfanilamides; D013844:Thiazoles / Q000494:pharmacology; D053778:Thiazolidines
chemical_list: D000199:Actins; D019086:Bridged Bicyclo Compounds, Heterocyclic; D004136:Dinitrobenzenes; D019384:Nucleic Acid Synthesis Inhibitors; D013424:Sulfanilamides; D013844:Thiazoles; D053778:Thiazolidines; D015638:Cytochalasin D; C012465:oryzalin; C037067:latrunculin A