Salt tolerance (STO), a stress-related protein, has a major role in light signalling

Plant J. 2007 Aug;51(4):563-74. doi: 10.1111/j.1365-313X.2007.03162.x. Epub 2007 Jul 2.


The salt tolerance protein (STO) of Arabidopsis was identified as a protein conferring salt tolerance to yeast cells. In order to uncover its function, we isolated an STO T-DNA insertion line and generated RNAi and overexpressor Arabidopsis plants. Here we present data on the hypocotyl growth of these lines indicating that STO acts as a negative regulator in phytochrome and blue-light signalling. Transcription analysis of STO uncovered a light and circadian dependent regulation of gene expression, and analysis of light-regulated genes revealed that STO is involved in the regulation of CHS expression during de-etiolation. In addition, we could show that CONSTITUTIVE PHOTOMORPHOGENESIS 1 (COP1) represses the transcription of STO and contributes to the destabilization of the protein in etiolated seedlings. Microscopic analysis revealed that the STO:eGFP fusion protein is located in the nucleus, accumulates in a light-dependent manner, and, in transient transformation assays in onion epidermal cells, co-localizes with COP1 in nuclear and cytoplasmic aggregations. However, the analysis of gain- and loss-of-function STO mutants in the cop1-4 background points towards a COP1-independent role during photomorphogenesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Arabidopsis / genetics
  • Arabidopsis / growth & development
  • Arabidopsis / metabolism*
  • Arabidopsis Proteins / genetics
  • Arabidopsis Proteins / metabolism
  • Arabidopsis Proteins / physiology*
  • Blotting, Northern
  • Blotting, Western
  • Cell Nucleus / metabolism
  • Circadian Rhythm / genetics
  • Gene Expression Regulation, Plant / radiation effects
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Hypocotyl / genetics
  • Hypocotyl / growth & development
  • Hypocotyl / metabolism
  • Light*
  • Microscopy, Fluorescence
  • Mutation
  • Phenotype
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Seedlings / genetics
  • Seedlings / growth & development
  • Seedlings / metabolism
  • Signal Transduction*


  • Arabidopsis Proteins
  • Recombinant Fusion Proteins
  • STO protein, Arabidopsis
  • Green Fluorescent Proteins