Photoperiodic flowering: time measurement mechanisms in leaves

Annu Rev Plant Biol. 2015;66:441-64. doi: 10.1146/annurev-arplant-043014-115555. Epub 2014 Dec 12.


Many plants use information about changing day length (photoperiod) to align their flowering time with seasonal changes to increase reproductive success. A mechanism for photoperiodic time measurement is present in leaves, and the day-length-specific induction of the FLOWERING LOCUS T (FT) gene, which encodes florigen, is a major final output of the pathway. Here, we summarize the current understanding of the molecular mechanisms by which photoperiodic information is perceived in order to trigger FT expression in Arabidopsis as well as in the primary cereals wheat, barley, and rice. In these plants, the differences in photoperiod are measured by interactions between circadian-clock-regulated components, such as CONSTANS (CO), and light signaling. The interactions happen under certain day-length conditions, as previously predicted by the external coincidence model. In these plants, the coincidence mechanisms are governed by multilayered regulation with numerous conserved as well as unique regulatory components, highlighting the breadth of photoperiodic regulation across plant species.

Keywords: CONSTANS; FLOWERING LOCUS T; external coincidence model; florigen; photoperiodism; seasonal flowering.

Publication types

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

MeSH terms

  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism
  • Circadian Clocks
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Flowers / growth & development*
  • Flowers / metabolism
  • Gene Expression Regulation, Plant*
  • Genes, Plant*
  • Photoperiod*
  • Plant Leaves / metabolism*
  • Plant Proteins / genetics*
  • Plant Proteins / metabolism
  • Plants / genetics*
  • Plants / metabolism
  • Transcription Factors / genetics
  • Transcription Factors / metabolism


  • Arabidopsis Proteins
  • CONSTANS protein, Arabidopsis
  • DNA-Binding Proteins
  • FT protein, Arabidopsis
  • Plant Proteins
  • Transcription Factors