Molecular basis of seasonal time measurement in Arabidopsis

Nature. 2002 Sep 19;419(6904):308-12. doi: 10.1038/nature00996.

Abstract

Several organisms have evolved the ability to measure daylength, or photoperiod, allowing them to adjust their development in anticipation of annual seasonal changes. Daylength measurement requires the integration of temporal information, provided by the circadian system, with light/dark discrimination, initiated by specific photoreceptors. Here we demonstrate that in Arabidopsis this integration takes place at the level of CONSTANS (CO) function. CO is a transcriptional activator that accelerates flowering time in long days, at least in part by inducing the expression of FLOWERING LOCUS T (FT). First, we show that precise clock control of the timing of CO expression, such that it is high during daytime only in long days, is critical for daylength discrimination. We then provide evidence that CO activation of FT expression requires the presence of light perceived through cryptochrome 2 (cry2) or phytochrome A (phyA). We conclude that an external coincidence mechanism, based on the endogenous circadian control of CO messenger RNA levels, and the modulation of CO function by light, constitutes the molecular basis for the regulation of flowering time by daylength in Arabidopsis.

Publication types

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

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / growth & development
  • Arabidopsis / physiology*
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism
  • Cryptochromes
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Darkness
  • Drosophila Proteins*
  • Eye Proteins*
  • Flavoproteins / genetics
  • Flavoproteins / metabolism
  • Gene Expression Regulation, Plant
  • Genes, Plant / genetics
  • Light
  • Mutation / genetics
  • Photoperiod*
  • Photoreceptor Cells, Invertebrate*
  • Phytochrome / genetics
  • Phytochrome / metabolism
  • Phytochrome A
  • Plant Structures / genetics
  • Plant Structures / growth & development
  • Plant Structures / physiology
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • RNA, Plant / genetics
  • RNA, Plant / metabolism
  • Receptors, G-Protein-Coupled
  • Seasons*
  • Time Factors
  • Transcription Factors / genetics
  • Transcription Factors / metabolism
  • Up-Regulation

Substances

  • Arabidopsis Proteins
  • CONSTANS protein, Arabidopsis
  • CRY1 protein, Arabidopsis
  • Cryptochromes
  • DNA-Binding Proteins
  • Drosophila Proteins
  • Eye Proteins
  • FT protein, Arabidopsis
  • Flavoproteins
  • PHYA protein, Arabidopsis
  • Phytochrome A
  • RNA, Messenger
  • RNA, Plant
  • Receptors, G-Protein-Coupled
  • Transcription Factors
  • cry protein, Drosophila
  • Phytochrome