title: Cell wall maturation of Arabidopsis trichomes is dependent on exocyst subunit EXO70H4 and involves callose deposition.
abstract: Arabidopsis (Arabidopsis thaliana) leaf trichomes are single-cell structures with a well-studied development, but little is understood about their function. Developmental studies focused mainly on the early shaping stages, and little attention has been paid to the maturation stage. We focused on the EXO70H4 exocyst subunit, one of the most up-regulated genes in the mature trichome. We uncovered EXO70H4-dependent development of the secondary cell wall layer, highly autofluorescent and callose rich, deposited only in the upper part of the trichome. The boundary is formed between the apical and the basal parts of mature trichome by a callose ring that is also deposited in an EXO70H4-dependent manner. We call this structure the Ortmannian ring (OR). Both the secondary cell wall layer and the OR are absent in the exo70H4 mutants. Ecophysiological aspects of the trichome cell wall thickening include interference with antiherbivore defense and heavy metal accumulation. Ultraviolet B light induces EXO70H4 transcription in a CONSTITUTIVE PHOTOMORPHOGENIC1-dependent way, resulting in stimulation of trichome cell wall thickening and the OR biogenesis. EXO70H4-dependent trichome cell wall hardening is a unique phenomenon, which may be conserved among a variety of the land plants. Our analyses support a concept that Arabidopsis trichome is an excellent model to study molecular mechanisms of secondary cell wall deposition.
authors.affiliation: Department of Experimental Plant Biology, Faculty of Sciences, Charles University, 12844 Prague, Czech Republic (I.K., Z.V., M.G., J.O., V.Z.);Institute of Experimental Botany, Academy of Sciences of the Czech Republic, 16502 Prague, Czech Republic (J.O., V.Z.); andDepartment of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland (S.R.) kulich@natur.cuni.cz.
authors.forename: Ivan
authors.initials: I
authors.lastname: Kulich
authors.affiliation: Department of Experimental Plant Biology, Faculty of Sciences, Charles University, 12844 Prague, Czech Republic (I.K., Z.V., M.G., J.O., V.Z.);Institute of Experimental Botany, Academy of Sciences of the Czech Republic, 16502 Prague, Czech Republic (J.O., V.Z.); andDepartment of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland (S.R.).
authors.forename: Zdeňka
authors.initials: Z
authors.lastname: Vojtíková
authors.affiliation: Department of Experimental Plant Biology, Faculty of Sciences, Charles University, 12844 Prague, Czech Republic (I.K., Z.V., M.G., J.O., V.Z.);Institute of Experimental Botany, Academy of Sciences of the Czech Republic, 16502 Prague, Czech Republic (J.O., V.Z.); andDepartment of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland (S.R.).
authors.forename: Matouš
authors.initials: M
authors.lastname: Glanc
authors.affiliation: Department of Experimental Plant Biology, Faculty of Sciences, Charles University, 12844 Prague, Czech Republic (I.K., Z.V., M.G., J.O., V.Z.);Institute of Experimental Botany, Academy of Sciences of the Czech Republic, 16502 Prague, Czech Republic (J.O., V.Z.); andDepartment of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland (S.R.).
authors.forename: Jitka
authors.initials: J
authors.lastname: Ortmannová
authors.affiliation: Department of Experimental Plant Biology, Faculty of Sciences, Charles University, 12844 Prague, Czech Republic (I.K., Z.V., M.G., J.O., V.Z.);Institute of Experimental Botany, Academy of Sciences of the Czech Republic, 16502 Prague, Czech Republic (J.O., V.Z.); andDepartment of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland (S.R.).
authors.forename: Sergio
authors.initials: S
authors.lastname: Rasmann
authors.affiliation: Department of Experimental Plant Biology, Faculty of Sciences, Charles University, 12844 Prague, Czech Republic (I.K., Z.V., M.G., J.O., V.Z.);Institute of Experimental Botany, Academy of Sciences of the Czech Republic, 16502 Prague, Czech Republic (J.O., V.Z.); andDepartment of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland (S.R.).
authors.forename: Viktor
authors.initials: V
authors.lastname: Žárský
mesh_terms: D017360:Arabidopsis / Q000378:metabolism* / Q000528:radiation effects / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism* / Q000648:ultrastructure; D003300:Copper / Q000378:metabolism; D048749:Cytokinesis / Q000528:radiation effects; D005453:Fluorescence; D005936:Glucans / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D021122:Protein Subunits / Q000378:metabolism*; D064201:Trichomes / Q000378:metabolism* / Q000528:radiation effects / Q000648:ultrastructure; D014466:Ultraviolet Rays; D033921:Vesicular Transport Proteins / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C000606466:EXO70H4 protein, Arabidopsis; D005936:Glucans; D021122:Protein Subunits; D033921:Vesicular Transport Proteins; D003300:Copper; C048306:callose