Identification of a cis-regulatory element for L1 layer-specific gene expression, which is targeted by an L1-specific homeodomain protein

Plant J. 2001 Jun;26(5):487-94. doi: 10.1046/j.1365-313x.2001.01047.x.


The Arabidopsis thaliana PROTODERMAL FACTOR1 (PDF1) gene encoding a putative extracellular proline-rich protein is exclusively expressed in the L1 layer of shoot apices and the protoderm of organ primordia. In order to identify essential cis-regulatory sequences required for the L1 layer-specific expression, a series of 5' deletions of the PDF1 promoter were fused to the beta-glucronidase (GUS) gene and introduced into Arabidopsis plants. Our analysis revealed that the minimum region necessary to confer L1-specific expression of PDF1 is confined within a 260-bp fragment upstream of the transcription start site. We identified an 8-bp motif in this region that is conserved between promoter regions of all the L1-specific genes so far cloned, and we designated it the L1 box. Electrophoretic mobility shift assays demonstrated that the L1-specific homeodomain protein ATML1 can bind to the L1 box sequence in vitro. The GUS expression in transgenic plants disappeared when a mutation that abolishes binding of ATML1 was introduced into the PDF1 l1 box sequence of the construct. These results suggest that the L1 box plays a crucial role in the regulation of PDF1 expression in L1 cells and that ATML1 could cooperate to drive L1-specific expression.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics*
  • Arabidopsis / growth & development
  • Arabidopsis Proteins*
  • Binding Sites
  • DNA Mutational Analysis
  • DNA, Plant
  • Genes, Reporter
  • Glucuronidase / genetics
  • Homeodomain Proteins / metabolism*
  • Meristem / genetics
  • Meristem / growth & development*
  • Plant Proteins / genetics*
  • Plant Shoots / genetics
  • Plant Shoots / growth & development*
  • Promoter Regions, Genetic
  • Protein Binding
  • Sequence Homology, Nucleic Acid
  • Tissue Distribution


  • ATML1 protein, Arabidopsis
  • Arabidopsis Proteins
  • DNA, Plant
  • Homeodomain Proteins
  • PDF1 protein, Arabidopsis
  • Plant Proteins
  • Glucuronidase