A quadruple photoreceptor mutant still keeps track of time

Curr Biol. 2000 Aug 24;10(16):1013-5. doi: 10.1016/s0960-9822(00)00651-5.


Time measurement and light detection are inextricably linked. Cryptochromes, the blue-light photoreceptors shared between plants and animals, are critical for circadian rhythms in flies and mice [1-3]. WC-1, a putative blue-light photoreceptor, is also essential for the maintenance of circadian rhythms in Neurospora [4]. In contrast, we report here that in Arabidopsis thaliana the double mutant lacking the cryptochromes cry1 and cry2, and even a quadruple mutant lacking the red/ far-red photoreceptor phytochromes phyA and phyB as well as cry1 and cry2, retain robust circadian rhythmicity. Interestingly, the quadruple mutant was nearly blind for developmental responses but perceived a light cue for entraining the circadian clock. These results indicate that cryptochromes and phytochromes are not essential components of the central oscillator in Arabidopsis and suggest that plants could possess specific photosensory mechanisms for temporal orientation, in addition to cryptochromes and phytochromes, which are used for both spatial and temporal adaptation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics*
  • Arabidopsis / physiology*
  • Arabidopsis Proteins
  • Circadian Rhythm*
  • Cryptochromes
  • Drosophila Proteins*
  • Eye Proteins*
  • Flavoproteins / genetics
  • Flavoproteins / metabolism
  • Mutation*
  • Photoreceptor Cells*
  • Photoreceptor Cells, Invertebrate*
  • Photosynthetic Reaction Center Complex Proteins / genetics*
  • Photosynthetic Reaction Center Complex Proteins / metabolism
  • Phytochrome / genetics
  • Phytochrome / metabolism
  • Phytochrome A
  • Phytochrome B
  • Receptors, G-Protein-Coupled
  • Transcription Factors*


  • Arabidopsis Proteins
  • CRY1 protein, Arabidopsis
  • Cry1 protein, mouse
  • Cry2 protein, mouse
  • Cryptochromes
  • Drosophila Proteins
  • Eye Proteins
  • Flavoproteins
  • PHYA protein, Arabidopsis
  • PHYB protein, Arabidopsis
  • Photosynthetic Reaction Center Complex Proteins
  • Phytochrome A
  • Receptors, G-Protein-Coupled
  • Transcription Factors
  • cry protein, Drosophila
  • Phytochrome
  • Phytochrome B