1. The COP1 Target SHI-RELATED SEQUENCE5 Directly Activates Photomorphogenesis-Promoting Genes.
- Author
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Yuan TT, Xu HH, Zhang Q, Zhang LY, and Lu YT
- Subjects
- Arabidopsis genetics, Arabidopsis Proteins genetics, Basic-Leucine Zipper Transcription Factors genetics, Gene Expression Regulation, Plant, Green Fluorescent Proteins genetics, Green Fluorescent Proteins metabolism, Hypocotyl genetics, Hypocotyl growth & development, Nuclear Proteins genetics, Plants, Genetically Modified, Promoter Regions, Genetic, Seedlings genetics, Seedlings physiology, Transcription Factors genetics, Ubiquitin-Protein Ligases genetics, Arabidopsis physiology, Arabidopsis Proteins metabolism, Ubiquitin-Protein Ligases metabolism
- Abstract
Plant seedlings undergo distinct developmental processes in the dark and in the light. Several genes, including ELONGATED HYPOCOTYL5 ( HY5 ), B-BOX PROTEIN21 ( BBX21 ), and BBX22 , have been identified as photomorphogenesis-promoting factors in Arabidopsis thaliana ; however, the overexpression of these genes does not induce photomorphogenesis in the dark. Using an activation-tagging approach, we identified SRS5ox , which overexpresses SHI-RELATED SEQUENCE5 ( SRS5 ) following induction with estradiol. SRS5 overexpression in SRS5ox and Pro35S:SRS5-GFP seedlings results in a constitutive photomorphogenesis phenotype in the dark, whereas SRS5 loss of function in the srs5-2 mutant results in long hypocotyls in the light. This indicates that SRS5 is a positive regulator of photomorphogenesis. Furthermore, SRS5 promotes photomorphogenesis by directly binding to the promoters of photomorphogenesis-promoting genes, such as HY5 , BBX21 , and BBX22 , and activating their expression, thus affecting the expression of downstream light-signaling genes. These data indicate that SRS5 acts in the upregulation of photomorphogenesis-promoting genes. In addition, CONSTITUTIVELY PHOTOMORPHOGENIC1 (COP1), which plays a central repressive role in seedling photomorphogenesis, directly ubiquitinates SRS5, promoting its degradation in the dark. Taken together, our results demonstrate that SRS5 directly activates the expression of downstream genes HY5 , BBX21 , and BBX22 and is a target of COP1-mediated degradation in Arabidopsis., (© 2018 American Society of Plant Biologists. All rights reserved.)
- Published
- 2018
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