title: The rotation of cellulose synthase trajectories is microtubule dependent and influences the texture of epidermal cell walls in Arabidopsis hypocotyls.
abstract: Plant shoots have thick, polylamellate outer epidermal walls based on crossed layers of cellulose microfibrils, but the involvement of microtubules in such wall lamellation is unclear. Recently, using a long-term movie system in which Arabidopsis seedlings were grown in a biochamber, the tracks along which cortical microtubules move were shown to undergo slow rotary movements over the outer surface of hypocotyl epidermal cells. Because microtubules are known to guide cellulose synthases over the short term, we hypothesised that this previously unsuspected microtubule rotation could, over the longer term, help explain the cross-ply structure of the outer epidermal wall. Here, we test that hypothesis using Arabidopsis plants expressing the cellulose synthase GFP-CESA3 and show that cellulose synthase trajectories do rotate over several hours. Neither microtubule-stabilising taxol nor microtubule-depolymerising oryzalin affected the linear rate of GFP-CESA3 movement, but both stopped the rotation of cellulose synthase tracks. Transmission electron microscopy revealed that drug-induced suppression of rotation alters the lamellation pattern, resulting in a thick monotonous wall layer. We conclude that microtubule rotation, rather than any hypothetical mechanism for wall self-assembly, has an essential role in developing cross-ply wall texture.
authors.affiliation: Department of Cell and Developmental Biology, John Innes Centre, Colney, Norwich NR47UH, UK.
authors.forename: Jordi
authors.initials: J
authors.lastname: Chan
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Crowell
authors.forename: Magdalena
authors.initials: M
authors.lastname: Eder
authors.forename: Grant
authors.initials: G
authors.lastname: Calder
authors.forename: Susan
authors.initials: S
authors.lastname: Bunnewell
authors.forename: Kim
authors.initials: K
authors.lastname: Findlay
authors.forename: Samantha
authors.initials: S
authors.lastname: Vernhettes
authors.forename: Herman
authors.initials: H
authors.lastname: Höfte
authors.forename: Clive
authors.initials: C
authors.lastname: Lloyd
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism* / Q000648:ultrastructure; D005964:Glucosyltransferases / Q000378:metabolism*; D018546:Hypocotyl / Q000201:enzymology* / Q000648:ultrastructure; D046529:Microscopy, Electron, Transmission; D008870:Microtubules / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D005964:Glucosyltransferases; C478648:cellulose synthase