Phytochrome and retrograde signalling pathways converge to antagonistically regulate a light-induced transcriptional network

Nat Commun. 2016 May 6;7:11431. doi: 10.1038/ncomms11431.

Abstract

Plastid-to-nucleus retrograde signals emitted by dysfunctional chloroplasts impact photomorphogenic development, but the molecular link between retrograde- and photosensory-receptor signalling has remained unclear. Here, we show that the phytochrome and retrograde signalling (RS) pathways converge antagonistically to regulate the expression of the nuclear-encoded transcription factor GLK1, a key regulator of a light-induced transcriptional network central to photomorphogenesis. GLK1 gene transcription is directly repressed by PHYTOCHROME-INTERACTING FACTOR (PIF)-class bHLH transcription factors in darkness, but light-activated phytochrome reverses this activity, thereby inducing expression. Conversely, we show that retrograde signals repress this induction by a mechanism independent of PIF mediation. Collectively, our data indicate that light at moderate levels acts through the plant's nuclear-localized sensory-photoreceptor system to induce appropriate photomorphogenic development, but at excessive levels, sensed through the separate plastid-localized RS system, acts to suppress such development, thus providing a mechanism for protection against photo-oxidative damage by minimizing the tissue exposure to deleterious radiation.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / growth & development
  • Arabidopsis / metabolism*
  • Arabidopsis / radiation effects*
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism
  • Basic Helix-Loop-Helix Transcription Factors / genetics
  • Basic Helix-Loop-Helix Transcription Factors / metabolism
  • Darkness
  • Gene Expression Regulation, Plant / radiation effects*
  • Gene Regulatory Networks / radiation effects
  • Light
  • Morphogenesis / radiation effects
  • Phytochrome / metabolism*
  • Plastids / genetics
  • Plastids / metabolism
  • Plastids / radiation effects
  • Signal Transduction / radiation effects*
  • Transcription Factors / genetics
  • Transcription Factors / metabolism

Substances

  • Arabidopsis Proteins
  • Basic Helix-Loop-Helix Transcription Factors
  • GLK1 protein, Arabidopsis
  • Transcription Factors
  • Phytochrome