The Arabidopsis COG1 gene encodes a Dof domain transcription factor and negatively regulates phytochrome signaling.
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.
Park
Don Ha
DH
Division of Molecular Life Sciences, Pohang University of Science and Technology, Pohang, Kyungbuk 790-784, Korea.
Lim
Pyung Ok
PO
Kim
Jeong Sik
JS
Cho
Dae Shik
DS
Hong
Sung Hyun
SH
Nam
Hong Gil
HG
D000595:Amino Acid Sequence; D000872:Anthocyanins / Q000378:metabolism; D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D005799:Genes, Dominant / Q000235:genetics; D008027:Light; D008969:Molecular Sequence Data; D009154:Mutation; D010834:Phytochrome / Q000494:pharmacology*; D017434:Protein Structure, Tertiary; D015398:Signal Transduction / Q000187:drug effects* / Q000528:radiation effects; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
D000872:Anthocyanins; D029681:Arabidopsis Proteins; C475876:COG1 protein, Arabidopsis; D014157:Transcription Factors; D010834:Phytochrome