Plants have evolved sensitive signaling systems to fine-tune photomorphogenesis in response to changing light environments. Light and low temperatures are known to regulate the expression of the COLD REGULATED (COR) genes COR27 and COR28, which influence the circadian clock, freezing tolerance, and flowering time. Blue light stabilizes the COR27 and COR28 proteins, but the underlying mechanism is unknown. We therefore performed a yeast two-hybrid screen using COR27- and COR28 as bait and identified the E3 ubiquitin ligase CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1) as an interactor. COR27 and COR28 physically interact with COP1, which is in turn responsible for their degradation in the dark. Furthermore, COR27 and COR28 promote hypocotyl elongation and act as negative regulators of photomorphogenesis in Arabidopsis (Arabidopsis thaliana). Genome-wide gene expression analysis showed that HY5, COR27, and COR28 co-regulate many common genes. COR27 interacts directly with HY5 and associates with the promoters of the HY5 target genes HY5 and PIF4, then regulates their transcription together with HY5. Our results demonstrate that COR27 and COR28 act as key regulators in the COP1–HY5 regulatory hub, by regulating the transcription of HY5 target genes together with HY5 to ensure proper skotomorphogenic growth in the dark and photomorphogenic development in the light.

植物已经进化出敏感的信号系统来微调光形态建成以响应不断变化的光环境。众所周知，光和低温可以调节COLD REGULATED ( COR ) 基因COR27和COR28的表达，影响生物钟、耐冻性和开花时间。蓝光可以稳定 COR27 和 COR28 蛋白，但其潜在机制尚不清楚。因此，我们使用 COR27- 和 COR28 作为诱饵进行了酵母双杂交筛选，并鉴定了 E3 泛素连接酶 CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1) 作为相互作用子。COR27 和 COR28 与 COP1 发生物理相互作用，进而导致它们在黑暗中降解。此外，COR27和COR28促进下胚轴伸长，并作为拟南芥（Arabidopsis thaliana）光形态发生的负调节因子。全基因组基因表达分析表明，HY5、COR27 和 COR28 共同调控许多常见基因。COR27 直接与 HY5 相互作用并与 HY5 靶基因HY5的启动子关联和PIF4，然后与 HY5 一起调节它们的转录。我们的结果表明，COR27 和 COR28 作为 COP1-HY5 调节中心的关键调节因子，通过与 HY5 一起调节 HY5 靶基因的转录，以确保黑暗中适当的暗形态生长和光照中的光形态发育。