1. COP1 Target SHI-RELATED SEQUENCE5 Directly Activates Photomorphogenesis-Promoting Genes.
- Author
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Yuan, Ting-Ting, Xu, Heng-Hao, Zhang, Qing, Zhang, Lin-Yu, and Lu, Ying-Tang
- Subjects
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GENETIC overexpression , *GENES , *PLANT photomorphogenesis , *GENE expression , *ESTRADIOL - 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. [ABSTRACT FROM AUTHOR]
- Published
- 2018
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