title: Overexpression of the epidermis-specific homeodomain-leucine zipper IV transcription factor Outer Cell Layer1 in maize identifies target genes involved in lipid metabolism and cuticle biosynthesis.
abstract: Transcription factors of the homeodomain-leucine zipper IV (HD-ZIP IV) family play crucial roles in epidermis-related processes. To gain further insight into the molecular function of OUTER CELL LAYER1 (OCL1), 14 target genes up- or down-regulated in transgenic maize (Zea mays) plants overexpressing OCL1 were identified. The 14 genes all showed partial coexpression with OCL1 in maize organs, and several of them shared preferential expression in the epidermis with OCL1. They encoded proteins involved in lipid metabolism, defense, envelope-related functions, or cuticle biosynthesis and include ZmWBC11a (for white brown complex 11a), an ortholog of AtWBC11 involved in the transport of wax and cutin molecules. In support of the annotations, OCL1-overexpressing plants showed quantitative and qualitative changes of cuticular wax compounds in comparison with wild-type plants. An increase in C24 to C28 alcohols was correlated with the transcriptional up-regulation of ZmFAR1, coding for a fatty acyl-coenzyme A reductase. Transcriptional activation of ZmWBC11a by OCL1 was likely direct, since transactivation in transiently transformed maize kernels was abolished by a deletion of the activation domain in OCL1 or mutations in the L1 box, a cis-element bound by HD-ZIP IV transcription factors. Our data demonstrate that, in addition to AP2/EREBP and MYB-type transcription factors, members of the HD-ZIP IV family contribute to the transcriptional regulation of genes involved in cuticle biosynthesis.
authors.affiliation: Université de Lyon, Ecole Normale Supérieure de Lyon, Université Lyon 1, Institut Fédératif de Recherche 128 BioSciences Lyon Gerland, Unité Reproduction et Développement des Plantes, F-69364 Lyon, France.
authors.forename: Marie
authors.initials: M
authors.lastname: Javelle
authors.forename: Vanessa
authors.initials: V
authors.lastname: Vernoud
authors.forename: Nathalie
authors.initials: N
authors.lastname: Depège-Fargeix
authors.forename: Christine
authors.initials: C
authors.lastname: Arnould
authors.forename: Delphine
authors.initials: D
authors.lastname: Oursel
authors.forename: Frédéric
authors.initials: F
authors.lastname: Domergue
authors.forename: Xavier
authors.initials: X
authors.lastname: Sarda
authors.forename: Peter M
authors.initials: PM
authors.lastname: Rogowsky
mesh_terms: D018506:Gene Expression Regulation, Plant; D055786:Gene Knockout Techniques; D017343:Genes, Plant / Q000235:genetics*; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D016350:Leucine Zippers / Q000235:genetics*; D050356:Lipid Metabolism / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D009928:Organ Specificity / Q000235:genetics; D019441:Plant Epidermis / Q000235:genetics*; D018515:Plant Leaves / Q000166:cytology / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D015203:Reproducibility of Results; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation / Q000235:genetics; D014170:Transformation, Genetic; D014885:Waxes / Q000378:metabolism; D003313:Zea mays / Q000235:genetics* / Q000276:immunology
chemical_list: D018398:Homeodomain Proteins; D010940:Plant Proteins; D014157:Transcription Factors; D014885:Waxes