CONSTANS‐LIKE (COL) family members are commonly implicated in light signal transduction during early photomorphogenesis. However, some of their functions remain unclear. Here, we propose a role for COL13 in hypocotyl elongation in Arabidopsis thaliana. We found that COL13 RNA accumulates at high levels in hypocotyls and that a disruption in the COL13 function via a T‐DNA insertion or RNAi led to the formation of longer hypocotyls of Arabidopsis seedlings under red light. On the contrary, overexpression of COL13 resulted in the formation of shorter hypocotyls. Using various genetic, genomic, and biochemical assays, we proved that another COL protein, COL3, directly binds to the promoter of COL13, and the promoter region of COL3 was targeted by the transcription factor LONG HYPOCOTYL 5 (HY5), to form an HY5‐COL3‐COL13 regulatory chain for regulating hypocotyl elongation under red light. Additionally, further study demonstrated that COL13 interacts with COL3, and COL13 promotes the interaction between COL3 and CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1), suggesting a possible COP1‐dependent COL3‐COL13 feedback pathway. Our results provide new information regarding the gene network in mediating hypocotyl elongation.

中文翻译：

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HY5-COL3-COL13调节链，用于控制拟南芥下胚轴的伸长

CONSTANS-LIKE（COL）家庭成员通常与早期光形态发生过程中的光信号转导有关。但是，它们的某些功能仍不清楚。在这里，我们提出了COL13在拟南芥下胚轴伸长中的作用。我们发现COL13 RNA在下胚轴中大量积累，并且通过T-DNA插入或RNAi对COL13功能的破坏导致在红灯下形成拟南芥幼苗更长的下胚轴。相反，COL13的过表达导致形成较短的下胚轴。使用各种遗传性，基因组的，和生物化学分析中，我们证明了另一个COL蛋白，COL3，直接结合的启动子COL13，和启动子区COL3由转录因子LONG胚轴5（HY5）靶向，以形成HY5 ‐COL3-COL13调节链，用于调节红灯下胚轴的伸长。此外，进一步的研究表明，COL13与COL3相互作用，并且COL13促进了COL3与本构性光生化因子1（COP1）之间的相互作用，这表明可能存在依赖于COP1的COL3-COL13反馈途径。我们的结果提供了有关介导下胚轴伸长的基因网络的新信息。