The epidermis coordinates auxin-induced stem growth in response to shade

Genes Dev. 2016 Jul 1;30(13):1529-41. doi: 10.1101/gad.283234.116.


Growth of a complex multicellular organism requires coordinated changes in diverse cell types. These cellular changes generate organs of the correct size, shape, and functionality. In plants, the growth hormone auxin induces stem elongation in response to shade; however, which cell types of the stem perceive the auxin signal and contribute to organ growth is poorly understood. Here, we blocked the transcriptional response to auxin within specific tissues to show that auxin signaling is required in many cell types for correct hypocotyl growth in shade, with a key role for the epidermis. Combining genetic manipulations in Arabidopsis thaliana with transcriptional profiling of the hypocotyl epidermis from Brassica rapa, we show that auxin acts in the epidermis in part by inducing activity of the locally acting, growth-promoting brassinosteroid pathway. Our findings clarify cell-specific auxin function in the hypocotyl and highlight the complexity of cell type interactions within a growing organ.

Keywords: auxin; brassinosteroid; epidermis; shade avoidance; stem growth.

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / growth & development
  • Arabidopsis Proteins / genetics
  • Brassica rapa / genetics
  • Brassica rapa / growth & development
  • Brassinosteroids / metabolism
  • Brassinosteroids / pharmacology
  • Gene Expression Profiling
  • Gene Expression Regulation, Plant* / radiation effects
  • Hypocotyl / cytology
  • Hypocotyl / drug effects
  • Hypocotyl / growth & development*
  • Hypocotyl / radiation effects
  • Indoleacetic Acids / metabolism*
  • Mutation
  • Nuclear Proteins / genetics
  • Plant Epidermis / metabolism*
  • Plant Epidermis / radiation effects
  • Signal Transduction
  • Sunlight
  • Transcription Factors


  • AXR3 protein, Arabidopsis
  • Arabidopsis Proteins
  • Brassinosteroids
  • Indoleacetic Acids
  • Nuclear Proteins
  • Transcription Factors