Light-induced nuclear import of phytochrome-A:GFP fusion proteins is differentially regulated in transgenic tobacco and Arabidopsis

Plant J. 2000 Apr;22(2):125-33. doi: 10.1046/j.1365-313x.2000.00729.x.


Phytochromes (phy) are a family of photoreceptors that control various aspects of light-dependent plant development. Phytochrome A (phyA) is responsible for the very low fluence response (VLFR) under inductive light conditions and for the high irradiance response (HIR) under continuous far-red light. We have recently shown that nuclear import of rice phyA:GFP is regulated by VLFR in transgenic tobacco. The import is preceded by very fast, light-induced formation of sequestered areas of phyA:GFP in the cytosol. Here we report that expression of the Arabidopsis phyA:GFP fusion protein in phyA-deficient Arabidopsis plants complements the mutant phenotype. In these transgenic Arabidopsis lines, both light-dependent cytosolic formation of sequestered areas of the phyA:GFP as well as VLFR or HIR-mediated nuclear import of the fusion protein was observed. By contrast, light-dependent nuclear import of the same fusion protein was induced only by continuous far-red light (HIR) but not by pulses of far-red light (VLFR) in transgenic tobacco. These results demonstrate that photoregulation of intracellular partitioning of the Arabidopsis phyA:GFP differs significantly in different genetic backgrounds.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / metabolism
  • Arabidopsis / physiology*
  • Arabidopsis Proteins
  • Cell Compartmentation / physiology
  • Cell Nucleus / metabolism*
  • Cell Nucleus / physiology
  • Green Fluorescent Proteins
  • Light*
  • Luminescent Proteins / genetics
  • Microscopy, Fluorescence
  • Phytochrome / genetics
  • Phytochrome / metabolism*
  • Phytochrome / physiology
  • Phytochrome A
  • Plants, Genetically Modified
  • Plants, Toxic*
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism*
  • Recombinant Fusion Proteins / physiology
  • Tobacco / metabolism
  • Tobacco / physiology*


  • Arabidopsis Proteins
  • Luminescent Proteins
  • PHYA protein, Arabidopsis
  • Phytochrome A
  • Recombinant Fusion Proteins
  • Phytochrome
  • Green Fluorescent Proteins