title: The balance between the MIR164A and CUC2 genes controls leaf margin serration in Arabidopsis.
abstract: CUP-SHAPED COTYLEDON1 (CUC1), CUC2, and CUC3 define the boundary domain around organs in the Arabidopsis thaliana meristem. CUC1 and CUC2 transcripts are targeted by a microRNA (miRNA), miR164, encoded by MIR164A, B, and C. We show that each MIR164 is transcribed to generate a large population of primary miRNAs of variable size with a locally conserved secondary structure around the pre-miRNA. We identified mutations in the MIR164A gene that deepen serration of the leaf margin. By contrast, leaves of plants overexpressing miR164 have smooth margins. Enhanced leaf serration was observed following the expression of an miR164-resistant CUC2 but not of an miR164-resistant CUC1. Furthermore, CUC2 inactivation abolished serration in mir164a mutants and the wild type, whereas CUC1 inactivation did not. Thus, CUC2 specifically controls leaf margin development. CUC2 and MIR164A are transcribed in overlapping domains at the margins of young leaf primordia, with transcription gradually restricted to the sinus, where the leaf margins become serrated. We suggest that leaf margin development is controlled by a two-step process in Arabidopsis. The pattern of serration is determined first, independently of CUC2 and miR164. The balance between coexpressed CUC2 and MIR164A then determines the extent of serration.
authors.affiliation: Laboratoire de Biologie Cellulaire, Institut Jean Pierre Bourgin, Institut National de la Recherche Agronomique, 78026 Versailles Cedex, France.
authors.forename: Krisztina
authors.initials: K
authors.lastname: Nikovics
authors.forename: Thomas
authors.initials: T
authors.lastname: Blein
authors.forename: Alexis
authors.initials: A
authors.lastname: Peaucelle
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Ishida
authors.forename: Halima
authors.initials: H
authors.lastname: Morin
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Aida
authors.forename: Patrick
authors.initials: P
authors.lastname: Laufs
mesh_terms: D000483:Alleles; D017360:Arabidopsis / Q000235:genetics / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D017124:Conserved Sequence; D035264:Flowers / Q000502:physiology; D015870:Gene Expression; D017343:Genes, Plant; D005816:Genetic Complementation Test; D035683:MicroRNAs / Q000737:chemistry / Q000378:metabolism*; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D009690:Nucleic Acid Conformation; D018515:Plant Leaves / Q000166:cytology / Q000196:embryology / Q000502:physiology*; D030821:Plants, Genetically Modified
chemical_list: D029681:Arabidopsis Proteins; C426007:CUC1 protein, Arabidopsis; C107294:CUC2 protein, Arabidopsis; D035683:MicroRNAs