title: DEFECTIVE KERNEL1 (DEK1) Regulates Cell Walls in the Leaf Epidermis.
abstract: The plant epidermis is crucial to survival, regulating interactions with the environment and controlling plant growth. The phytocalpain DEFECTIVE KERNEL1 (DEK1) is a master regulator of epidermal differentiation and maintenance, acting upstream of epidermis-specific transcription factors, and is required for correct cell adhesion. It is currently unclear how changes in DEK1 lead to cellular defects in the epidermis and the pathways through which DEK1 acts. We have combined growth kinematic studies, cell wall analysis, and transcriptional analysis of genes downstream of DEK1 to determine the cause of phenotypic changes observed in DEK1-modulated lines of Arabidopsis (Arabidopsis thaliana). We reveal a novel role for DEK1 in the regulation of leaf epidermal cell wall structure. Lines with altered DEK1 activity have epidermis-specific changes in the thickness and polysaccharide composition of cell walls that likely underlie the loss of adhesion between epidermal cells in plants with reduced levels of DEK1 and changes in leaf shape and size in plants constitutively overexpressing the active CALPAIN domain of DEK1. Calpain-overexpressing plants also have increased levels of cellulose and pectins in epidermal cell walls, and this is correlated with the expression of several cell wall-related genes, linking transcriptional regulation downstream of DEK1 with cellular effects. These findings significantly advance our understanding of the role of the epidermal cell walls in growth regulation and establish a new role for DEK1 in pathways regulating epidermal cell wall deposition and remodeling.
authors.affiliation: Australian Research Council Centre of Excellence in Plant Cell Walls, School of BioSciences, University of Melbourne, Parkville, Victoria 3010, Australia (D.A., M.S.D., A.B., K.L.J.); and.|Laboratoire Reproduction et Développement des Plantes, Université de Lyon, Centre National de la Recherche Scientifique Unité Mixte de Recherche 5667, Institut National de la Recherche Agronomique Unité Mixte de Recherche 0879, Ecole Normale Supérieure de Lyon, Lyon F-69342, France (R.G., G.C.I.).
authors.forename: Dhika
authors.initials: D
authors.lastname: Amanda
authors.affiliation: Australian Research Council Centre of Excellence in Plant Cell Walls, School of BioSciences, University of Melbourne, Parkville, Victoria 3010, Australia (D.A., M.S.D., A.B., K.L.J.); and.|Laboratoire Reproduction et Développement des Plantes, Université de Lyon, Centre National de la Recherche Scientifique Unité Mixte de Recherche 5667, Institut National de la Recherche Agronomique Unité Mixte de Recherche 0879, Ecole Normale Supérieure de Lyon, Lyon F-69342, France (R.G., G.C.I.).
authors.forename: Monika S
authors.identifier: 0000-0002-8921-2725
authors.initials: MS
authors.lastname: Doblin
authors.affiliation: Australian Research Council Centre of Excellence in Plant Cell Walls, School of BioSciences, University of Melbourne, Parkville, Victoria 3010, Australia (D.A., M.S.D., A.B., K.L.J.); and.|Laboratoire Reproduction et Développement des Plantes, Université de Lyon, Centre National de la Recherche Scientifique Unité Mixte de Recherche 5667, Institut National de la Recherche Agronomique Unité Mixte de Recherche 0879, Ecole Normale Supérieure de Lyon, Lyon F-69342, France (R.G., G.C.I.).
authors.forename: Roberta
authors.identifier: 0000-0001-8299-7649
authors.initials: R
authors.lastname: Galletti
authors.affiliation: Australian Research Council Centre of Excellence in Plant Cell Walls, School of BioSciences, University of Melbourne, Parkville, Victoria 3010, Australia (D.A., M.S.D., A.B., K.L.J.); and.|Laboratoire Reproduction et Développement des Plantes, Université de Lyon, Centre National de la Recherche Scientifique Unité Mixte de Recherche 5667, Institut National de la Recherche Agronomique Unité Mixte de Recherche 0879, Ecole Normale Supérieure de Lyon, Lyon F-69342, France (R.G., G.C.I.).
authors.forename: Antony
authors.identifier: 0000-0001-7483-8605
authors.initials: A
authors.lastname: Bacic
authors.affiliation: Australian Research Council Centre of Excellence in Plant Cell Walls, School of BioSciences, University of Melbourne, Parkville, Victoria 3010, Australia (D.A., M.S.D., A.B., K.L.J.); and.|Laboratoire Reproduction et Développement des Plantes, Université de Lyon, Centre National de la Recherche Scientifique Unité Mixte de Recherche 5667, Institut National de la Recherche Agronomique Unité Mixte de Recherche 0879, Ecole Normale Supérieure de Lyon, Lyon F-69342, France (R.G., G.C.I.).
authors.forename: Gwyneth C
authors.initials: GC
authors.lastname: Ingram
authors.affiliation: Australian Research Council Centre of Excellence in Plant Cell Walls, School of BioSciences, University of Melbourne, Parkville, Victoria 3010, Australia (D.A., M.S.D., A.B., K.L.J.); and kim.johnson@unimelb.edu.au.|Laboratoire Reproduction et Développement des Plantes, Université de Lyon, Centre National de la Recherche Scientifique Unité Mixte de Recherche 5667, Institut National de la Recherche Agronomique Unité Mixte de Recherche 0879, Ecole Normale Supérieure de Lyon, Lyon F-69342, France (R.G., G.C.I.) kim.johnson@unimelb.edu.au.
authors.forename: Kim L
authors.identifier: 0000-0001-6917-7742
authors.initials: KL
authors.lastname: Johnson
mesh_terms: D017360:Arabidopsis / Q000166:cytology* / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002154:Calpain / Q000235:genetics / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism* / Q000648:ultrastructure; D000939:Epitopes / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D007700:Kinetics; D008954:Models, Biological; D010368:Pectins / Q000378:metabolism; D010641:Phenotype; D063245:Plant Development / Q000235:genetics; D019441:Plant Epidermis / Q000166:cytology* / Q000378:metabolism* / Q000648:ultrastructure; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D029681:Arabidopsis Proteins; D000939:Epitopes; D012333:RNA, Messenger; D010368:Pectins; D002154:Calpain; C507125:DEK1 protein, Arabidopsis