Regulation of MIR165/166 by class II and class III homeodomain leucine zipper proteins establishes leaf polarity

Proc Natl Acad Sci U S A. 2016 Oct 18;113(42):11973-11978. doi: 10.1073/pnas.1516110113. Epub 2016 Oct 3.


A defining feature of plant leaves is their flattened shape. This shape depends on an antagonism between the genes that specify adaxial (top) and abaxial (bottom) tissue identity; however, the molecular nature of this antagonism remains poorly understood. Class III homeodomain leucine zipper (HD-ZIP) transcription factors are key mediators in the regulation of adaxial-abaxial patterning. Their expression is restricted adaxially during early development by the abaxially expressed microRNA (MIR)165/166, yet the mechanism that restricts MIR165/166 expression to abaxial leaf tissues remains unknown. Here, we show that class III and class II HD-ZIP proteins act together to repress MIR165/166 via a conserved cis-element in their promoters. Organ morphology and tissue patterning in plants, therefore, depend on a bidirectional repressive circuit involving a set of miRNAs and its targets.

Keywords: MIR165/166; class II HD-ZIP; class III HD-ZIP; leaf morphogenesis; organ patterning.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / metabolism
  • Arabidopsis Proteins / genetics
  • Biomarkers
  • Conserved Sequence
  • Gene Expression Regulation, Plant
  • Homeodomain Proteins / chemistry
  • Homeodomain Proteins / genetics*
  • Homeodomain Proteins / metabolism
  • Leucine Zippers / genetics*
  • MicroRNAs / genetics*
  • Models, Biological
  • Plant Development / genetics*
  • Plant Leaves / genetics*
  • Protein Binding
  • Quantitative Trait, Heritable
  • Response Elements


  • Arabidopsis Proteins
  • Biomarkers
  • Homeodomain Proteins
  • MicroRNAs