The Arabidopsis COG1 gene encodes a Dof domain transcription factor and negatively regulates phytochrome signaling

• Published in: The Plant journal : for cell and molecular biology 2003-04, Vol.34 (2), p.161-171
• Main Authors: Park, Don Ha, Lim, Pyung Ok, Kim, Jeong Sik, Cho, Dae Shik, Hong, Sung Hyun, Nam, Hong Gil
• Format: Article
• Language: English
• Subjects: activation tagging; Amino Acid Sequence; Anthocyanins - metabolism; Arabidopsis - genetics; Arabidopsis - growth & development; Arabidopsis - metabolism; Arabidopsis - radiation effects; Arabidopsis Proteins - chemistry; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Biological and medical sciences; Cell Nucleus - metabolism; Dof transcription factor; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation, Plant; Genes, Dominant - genetics; Light; light signaling; Molecular Sequence Data; Mutation; Physical agents; phytochrome; Phytochrome - pharmacology; Plant physiology and development; Protein Structure, Tertiary; Signal Transduction - drug effects; Signal Transduction - radiation effects; Transcription Factors - chemistry; Transcription Factors - genetics; Transcription Factors - metabolism; Vegetative apparatus, growth and morphogenesis. Senescence
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1046/j.1365-313X.2003.01710.x

Summary Light is a critical environmental factor that influences almost all developmental aspects of plants, including seed germination, seedling morphogenesis, and transition to reproductive growth. Plants have therefore developed an intricate network of mechanisms to perceive and process environmental light information. To further characterize the molecular basis of light‐signaling processes in plants, we screened an activation tagging pool of Arabidopsis for altered photoresponses. A dominant mutation, cog1‐D, attenuated various red (R) and far‐red (FR) light‐dependent photoresponses. The mutation was caused by overexpression of a gene encoding a member of the Dof family of transcription factors. The photoresponses in Arabidopsis were inversely correlated with the expression levels of COG1 mRNA. When the COG1 gene was overexpressed in transgenic plants, the plants exhibited hyposensitive responses to R and FR light in a manner inversely dependent on COG1 mRNA levels. On the other hand, transgenic lines expressing antisense COG1 were hypersensitive to R and FR light. Expression of the COG1 gene is light inducible and requires phytochrome A (phyA) for FR light‐induced expression and phytochrome B (phyB) for R light‐induced expression. Thus, the COG1 gene functions as a negative regulator in both the phyA‐ and phyB‐signaling pathways. We suggest that these phytochromes positively regulate the expression of COG1, a negative regulator, as a mechanism for fine tuning the light‐signaling pathway.