title: Regulation of shoot epidermal cell differentiation by a pair of homeodomain proteins in Arabidopsis.
abstract: In higher plants, the outermost cell layer (L1) of the shoot apex gives rise to the epidermis of shoot organs. Our previous study demonstrated that an 8-bp motif named the L1 box functions as a cis-regulatory element for L1-specific gene expression in the shoot system of Arabidopsis: We show here that PROTODERMAL FACTOR2 (PDF2), a member of the HD-GL2 class of homeobox genes, is expressed exclusively in the L1 of shoot meristems and that recombinant PDF2 protein specifically binds to the L1 box in vitro. Although knockout mutants of PDF2 and ATML1, another L1-specific HD-GL2 class gene sharing the highest homology with PDF2, display normal shoot development, the double mutant results in severe defects in shoot epidermal cell differentiation. This suggests that PDF2 and ATML1 are functionally interchangeable and play a critical role in maintaining the identity of L1 cells, possibly by interacting with their L1 box and those of downstream target-gene promoters.
authors.affiliation: Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan.
authors.forename: Mitsutomo
authors.initials: M
authors.lastname: Abe
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Katsumata
authors.forename: Yoshibumi
authors.initials: Y
authors.lastname: Komeda
authors.forename: Taku
authors.initials: T
authors.lastname: Takahashi
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism*; D002454:Cell Differentiation / Q000502:physiology*; D003001:Cloning, Molecular; D035264:Flowers / Q000502:physiology; D018506:Gene Expression Regulation, Plant; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D019441:Plant Epidermis / Q000166:cytology; D018520:Plant Shoots / Q000166:cytology* / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic
chemical_list: C103790:ATML1 protein, Arabidopsis; D029681:Arabidopsis Proteins; D018398:Homeodomain Proteins; C472305:PDF2 protein, Arabidopsis