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

• Published in: The Plant journal : for cell and molecular biology 2007-08, Vol.51 (4), p.563-574
• Main Authors: Indorf, Martin, Cordero, Julio, Neuhaus, Gunther, Rodríguez-Franco, Marta
• Format: Article
• Language: English
• Subjects: Adaptation to environment and cultivation conditions; Agronomy. Soil science and plant productions; Allium cepa; Arabidopsis; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis - metabolism; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis Proteins - physiology; B-box; Biological and medical sciences; Blotting, Northern; Blotting, Western; blue light; Botany; Cell Nucleus - metabolism; Cellular biology; Circadian Rhythm - genetics; CONSTITUTIVE PHOTOMORPHOGENESIS 1; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant - radiation effects; Genetics and breeding of economic plants; Green Fluorescent Proteins - genetics; Green Fluorescent Proteins - metabolism; Hypocotyl - genetics; Hypocotyl - growth & development; Hypocotyl - metabolism; Light; light signalling; Microscopy, Fluorescence; Mutation; Phenotype; phytochrome; Proteins; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Salt; Seedlings - genetics; Seedlings - growth & development; Seedlings - metabolism; Signal Transduction; Varietal selection. Specialized plant breeding, plant breeding aims; Zn-finger protein
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/j.1365-313X.2007.03162.x

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.