title: Salt tolerance (STO), a stress-related protein, has a major role in light signalling.
abstract: 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.
authors.affiliation: Department of Cell Biology, University of Freiburg, Freiburg D-79104, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Indorf
authors.forename: Julio
authors.initials: J
authors.lastname: Cordero
authors.forename: Gunther
authors.initials: G
authors.lastname: Neuhaus
authors.forename: Marta
authors.initials: M
authors.lastname: Rodríguez-Franco
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015152:Blotting, Northern; D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism; D002940:Circadian Rhythm / Q000235:genetics; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D018546:Hypocotyl / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D008027:Light; D008856:Microscopy, Fluorescence; D009154:Mutation; D010641:Phenotype; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D036226:Seedlings / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D029681:Arabidopsis Proteins; D011993:Recombinant Fusion Proteins; C100336:STO protein, Arabidopsis; D049452:Green Fluorescent Proteins