title: ATML1 promotes epidermal cell differentiation in Arabidopsis shoots.
abstract: Molecular mechanisms that generate distinct tissue layers in plant shoots are not well understood. ATML1, an Arabidopsis homeobox gene, is expressed in the outermost cell layer, beginning at an early stage of development. The promoters of many epidermis-specific genes, including ATML1, contain an ATML1-binding site called an L1 box, suggesting that ATML1 regulates epidermal cell fate. Here, we show that overexpression of ATML1 was sufficient to activate the expression of epidermal genes and to induce epidermis-related traits such as the formation of stomatal guard cells and trichome-like cells in non-epidermal seedling tissues. Detailed observation of the division planes of these ectopic stomatal cells suggested that a near-surface position, as well as epidermal cell identity, were required for regular anticlinal cell division, as seen in wild-type epidermis. Moreover, analyses of a loss-of-function mutant and overexpressors implied that differentiation of epidermal cells was associated with repression of mesophyll cell fate. Collectively, our studies contribute new information about the molecular basis of cell fate determination in different layers of plant aerial organs.
authors.affiliation: Department of Biological Sciences, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka, Japan. shinobu_takada@bio.sci.osaka-u.ac.jp
authors.forename: Shinobu
authors.initials: S
authors.lastname: Takada
authors.forename: Nozomi
authors.initials: N
authors.lastname: Takada
authors.forename: Ayaka
authors.initials: A
authors.lastname: Yoshida
mesh_terms: D017360:Arabidopsis / Q000166:cytology* / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation; D002455:Cell Division; D004958:Estradiol; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D058503:Mesophyll Cells / Q000166:cytology / Q000378:metabolism; D010641:Phenotype; D059828:Plant Cells / Q000378:metabolism; D019441:Plant Epidermis / Q000166:cytology / Q000378:metabolism*; D018515:Plant Leaves / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D018520:Plant Shoots / Q000235:genetics / Q000378:metabolism*; D054046:Plant Stomata / Q000166:cytology / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000166:cytology / Q000378:metabolism; D011401:Promoter Regions, Genetic
chemical_list: C103790:ATML1 protein, Arabidopsis; D029681:Arabidopsis Proteins; C402598:At2g26250 protein, Arabidopsis; D018398:Homeodomain Proteins; D004958:Estradiol