Phot1 and phot2 mediate blue light regulation of stomatal opening

Nature. 2001 Dec 6;414(6864):656-60. doi: 10.1038/414656a.


The stomatal pores of higher plants allow for gaseous exchange into and out of leaves. Situated in the epidermis, they are surrounded by a pair of guard cells which control their opening in response to many environmental stimuli, including blue light. Opening of the pores is mediated by K(+) accumulation in guard cells through a K(+) channel and driven by an inside-negative electrical potential. Blue light causes phosphorylation and activation of the plasma membrane H(+)-ATPase that creates this potential. Thus far, no blue light receptor mediating stomatal opening has been identified, although the carotenoid, zeaxanthin, has been proposed. Arabidopsis mutants deficient in specific blue-light-mediated responses have identified four blue light receptors, cryptochrome 1 (cry1), cryptochrome 2 (cry2), phot1 and phot2. Here we show that in a double mutant of phot1 and phot2 stomata do not respond to blue light although single mutants are phenotypically normal. These results demonstrate that phot1 and phot2 act redundantly as blue light receptors mediating stomatal opening.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / physiology*
  • Cell Membrane / enzymology
  • Cell Membrane / radiation effects
  • Light*
  • Mutation
  • Phosphoproteins / genetics
  • Phosphoproteins / physiology*
  • Photosynthetic Reaction Center Complex Proteins* / genetics
  • Plant Epidermis / physiology*
  • Plant Epidermis / radiation effects
  • Protein-Serine-Threonine Kinases / genetics
  • Protein-Serine-Threonine Kinases / physiology
  • Proton-Translocating ATPases / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction


  • Arabidopsis Proteins
  • PHOT2 protein, Arabidopsis
  • Phosphoproteins
  • Photosynthetic Reaction Center Complex Proteins
  • NPH1 protein, Arabidopsis
  • Protein-Serine-Threonine Kinases
  • Proton-Translocating ATPases