title: Brassinosteroid production and signaling differentially control cell division and expansion in the leaf.
abstract: Brassinosteroid (BR) hormones control plant growth through acting on both cell expansion and division. Here, we examined the role of BRs in leaf growth using the Arabidopsis BR-deficient mutant constitutive photomorphogenesis and dwarfism (cpd). We show that the reduced size of cpd leaf blades is a result of a decrease in cell size and number, as well as in venation length and complexity. Kinematic growth analysis and tissue-specific marker gene expression revealed that the leaf phenotype of cpd is associated with a prolonged cell division phase and delayed differentiation. cpd-leaf-rescue experiments and leaf growth analysis of BR biosynthesis and signaling gain-of-function mutants showed that BR production and BR receptor-dependent signaling differentially control the balance between cell division and expansion in the leaf. Investigation of cell cycle markers in leaves of cpd revealed the accumulation of mitotic proteins independent of transcription. This correlated with an increase in cyclin-dependent kinase activity, suggesting a role for BRs in control of mitosis.
authors.affiliation: Department of Plant Systems Biology, VIB, B-9052, Ghent, Belgium.|Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052, Ghent, Belgium.
authors.forename: Miroslava K
authors.initials: MK
authors.lastname: Zhiponova
authors.affiliation: Department of Plant Systems Biology, VIB, B-9052, Ghent, Belgium.|Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052, Ghent, Belgium.
authors.forename: Isabelle
authors.initials: I
authors.lastname: Vanhoutte
authors.affiliation: Department of Plant Systems Biology, VIB, B-9052, Ghent, Belgium.|Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052, Ghent, Belgium.
authors.forename: Véronique
authors.initials: V
authors.lastname: Boudolf
authors.affiliation: Department of Plant Systems Biology, VIB, B-9052, Ghent, Belgium.|Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052, Ghent, Belgium.
authors.forename: Camilla
authors.initials: C
authors.lastname: Betti
authors.affiliation: Department of Plant Systems Biology, VIB, B-9052, Ghent, Belgium.|Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052, Ghent, Belgium.
authors.forename: Stijn
authors.initials: S
authors.lastname: Dhondt
authors.affiliation: Department of Plant Systems Biology, VIB, B-9052, Ghent, Belgium.|Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052, Ghent, Belgium.
authors.forename: Frederik
authors.initials: F
authors.lastname: Coppens
authors.affiliation: Department of Plant Systems Biology, VIB, B-9052, Ghent, Belgium.|Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052, Ghent, Belgium.
authors.forename: Evelien
authors.initials: E
authors.lastname: Mylle
authors.affiliation: Department of Plant Systems Biology, VIB, B-9052, Ghent, Belgium.|Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052, Ghent, Belgium.
authors.forename: Sara
authors.initials: S
authors.lastname: Maes
authors.affiliation: Molecular Genetics Department, Centre for Research in Agricultural Genomics CSIC-IRTA-UAB, 08013, Barcelona, Spain.
authors.forename: Mary-Paz
authors.initials: MP
authors.lastname: González-García
authors.affiliation: Molecular Genetics Department, Centre for Research in Agricultural Genomics CSIC-IRTA-UAB, 08013, Barcelona, Spain.
authors.forename: Ana I
authors.initials: AI
authors.lastname: Caño-Delgado
authors.affiliation: Department of Plant Systems Biology, VIB, B-9052, Ghent, Belgium.|Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052, Ghent, Belgium.
authors.forename: Dirk
authors.initials: D
authors.lastname: Inzé
authors.affiliation: Department of Biology, University of Antwerp, B-2020, Antwerp, Belgium.
authors.forename: Gerrit T S
authors.initials: GTS
authors.lastname: Beemster
authors.affiliation: Department of Plant Systems Biology, VIB, B-9052, Ghent, Belgium.|Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052, Ghent, Belgium.
authors.forename: Lieven
authors.initials: L
authors.lastname: De Veylder
authors.affiliation: Department of Plant Systems Biology, VIB, B-9052, Ghent, Belgium.|Department of Plant Biotechnology and Bioinformatics, Ghent University, B-9052, Ghent, Belgium.
authors.forename: Eugenia
authors.initials: E
authors.lastname: Russinova
mesh_terms: D017360:Arabidopsis / Q000166:cytology* / Q000187:drug effects / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000378:metabolism; D060406:Brassinosteroids / Q000096:biosynthesis* / Q000378:metabolism / Q000494:pharmacology; D002452:Cell Count; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D048429:Cell Size / Q000187:drug effects; D008938:Mitosis / Q000187:drug effects; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D018515:Plant Leaves / Q000166:cytology* / Q000187:drug effects / Q000254:growth & development*; D011494:Protein Kinases / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D029681:Arabidopsis Proteins; D060406:Brassinosteroids; D011494:Protein Kinases; C108270:BRI1 protein, Arabidopsis