title: Regulation of planar growth by the Arabidopsis AGC protein kinase UNICORN.
abstract: The spatial coordination of growth is of central importance for the regulation of plant tissue architecture. Individual layers, such as the epidermis, are clonally propagated and structurally maintained by symmetric cell divisions that are oriented along the plane of the layer. The developmental control of this process is poorly understood. The simple cellular basis and sheet-like structure of Arabidopsis integuments make them an attractive model system to address planar growth. Here we report on the characterization of the Arabidopsis UNICORN (UCN) gene. Analysis of ucn integuments reveals localized distortion of planar growth, eventually resulting in an ectopic multicellular protrusion. In addition, ucn mutants exhibit ectopic growth in filaments and petals, as well as aberrant embryogenesis. We further show that UCN encodes an active AGC VIII kinase. Genetic, biochemical, and cell biological data suggest that UCN suppresses ectopic growth in integuments by directly repressing the KANADI transcription factor ABERRANT TESTA SHAPE. Our findings indicate that UCN represents a unique plant growth regulator that maintains planar growth of integuments by repressing a developmental regulator involved in the control of early integument growth and polarity.
authors.affiliation: Entwicklungsbiologie der Pflanzen, Wissenschaftszentrum Weihenstephan, Technische Universität München, 85354 Freising, Germany.
authors.forename: Balaji
authors.initials: B
authors.lastname: Enugutti
authors.forename: Charlotte
authors.initials: C
authors.lastname: Kirchhelle
authors.forename: Maxi
authors.initials: M
authors.lastname: Oelschner
authors.forename: Ramón Angel
authors.initials: RA
authors.lastname: Torres Ruiz
authors.forename: Ivo
authors.initials: I
authors.lastname: Schliebner
authors.forename: Dario
authors.initials: D
authors.lastname: Leister
authors.forename: Kay
authors.initials: K
authors.lastname: Schneitz
mesh_terms: D017360:Arabidopsis / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002455:Cell Division / Q000502:physiology*; D004591:Electrophoresis, Polyacrylamide Gel; D035264:Flowers / Q000254:growth & development*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000502:physiology*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D034582:Integumentary System / Q000254:growth & development*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D029681:Arabidopsis Proteins; C511852:KAN4 protein, Arabidopsis; D014157:Transcription Factors; D017346:Protein Serine-Threonine Kinases; C576669:UNICORN protein, Arabidopsis