Light signaling plays a substantial role in regulating plant development, including the differentiation and elongation of single-celled tissue. However, the identity of the regulatory machine that affects light signaling on root hair cell (RHC) development remains unclear. Here, we investigated how darkness inhibits differentiation and elongation of RHC in Arabidopsis (Arabidopsis thaliana). We found that light promotes the growth and development of RHC. RNA-seq analysis showed that light signaling regulates the differentiation of RHC by promoting the expression of specific genes in the root epidermis associated with cell wall remodeling, JA, auxin, and ethylene signaling pathways. Together, these genes integrate light and phytohormone signals with root hair development. Our investigation also revealed that the core light signal factor ELONGATED HYPOCOTYL 5 (HY5) directly interacts with the key root hair development factor ROOT HAIR DEFECTIVE6 (RHD6), which promotes the transcription of RSL4. However, CONSTITUTIVE PHOTOMORPHOGENIC 1 (COP1) repressed RHD6 function through the COP1-HY5 complex. Our genetic studies confirm associations between RHD6, HY5, and COP1, indicating that RHD6 largely depends on HY5 for root hair development. Ultimately, our work suggests a central COP1-HY5-RHD6 regulatory module that integrates light signaling and root hair development with several downstream pathways, offering perspectives to decipher single-celled root hair development.

中文翻译：

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E3 泛素连接酶 COP1 和转录因子 HY5 和 RHD6 整合了光信号传导和根毛发育


光信号在调节植物发育中起着重要作用，包括单细胞组织的分化和伸长。然而，影响根毛细胞 （RHC） 发育光信号的调节机器的身份仍不清楚。在这里，我们研究了黑暗如何抑制拟南芥 （Arabidopsis thaliana） 中 RHC 的分化和伸长。我们发现光促进 RHC 的生长和发育。RNA-seq 分析显示，光信号通过促进与细胞壁重塑、JA、生长素和乙烯信号通路相关的根表皮中特定基因的表达来调节 RHC 的分化。这些基因一起将光和植物激素信号与根毛发育相结合。我们的研究还揭示了核心光信号因子 ELONGATED HYPOCOTYL 5 （HY5） 直接与关键的根毛发育因子 ROOT HAIR DEFECTIVE6 （RHD6） 相互作用，从而促进 RSL4 的转录。然而，组成型光形态发生 1 （COP1） 通过 COP1-HY5 复合物抑制 RHD6 功能。我们的遗传研究证实了 RHD6、HY5 和 COP1 之间的关联，表明 RHD6 在很大程度上依赖于 HY5 进行根毛发育。最终，我们的工作提出了一个中央 COP1-HY5-RHD6 调节模块，它将光信号传导和根毛发育与几个下游途径相结合，为破译单细胞根毛发育提供了前景。