UV RESISTANCE LOCUS 8 (UVR8) is a photoreceptor that regulates UV-B photomorphogenesis in plants. UV-B photon perception promotes UVR8 homodimer dissociation into monomer, which is reverted to homodimer post UV-B, forming a complete photocycle. UVR8 monomer interacts with CONSTITUTIVELY PHOTOMORPHOGENEIC 1 (COP1) to initiate UV-B signaling. The function and mechanism of Arabidopsis UVR8 (AtUVR8) are extensively investigated, however, little is known about UVR8 and its signaling mechanisms in other plant species. Tomato is a widely used model plant for horticulture research. In this report we tested whether an ortholog of AtUVR8 in Tomato (SIUVR8) can complement Arabidopsis uvr8 mutant and whether the above-mentioned key signaling mechanisms of UVR8 are conserved. Heterologous expressed SIUVR8 in an Arabidopsis uvr8 null mutant rescued the uvr8 mutant in the tested UV-B responses including hypocotyl elongation, UV-B target gene expression and anthocyanin accumulation, demonstrating that the SIUVR8 is a putative UV-B photoreceptor. Moreover, in response to UV-B, SIUVR8 forms a protein complex with Arabidopsis COP1 in plants, suggesting conserved signaling mechanism. SIUVR8 exhibits similar photocycle as AtUVR8 in plants, which highlights conserved photoreceptor activation and inactivation mechanisms.

中文翻译：

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拟南芥中番茄 UVR8 的表达揭示了保守的光感受器功能

UV RESISTANCE LOCUS 8 (UVR8) 是一种调节植物中 UV-B 光形态发生的光感受器。UV-B 光子感知促进 UVR8 同二聚体解离成单体，在 UV-B 后恢复为同二聚体，形成完整的光循环。UVR8 单体与 CONSTITUTIVELY PHOTOMORPHOGENEIC 1 (COP1) 相互作用以启动 UV-B 信号。拟南芥 UVR8 (AtUVR8) 的功能和机制已被广泛研究，但是，对 UVR8 及其在其他植物物种中的信号传导机制知之甚少。番茄是一种广泛用于园艺研究的模式植物。在本报告中，我们测试了番茄中 AtUVR8 的直系同源物 (SIUVR8) 是否可以补充拟南芥 uvr8 突变体，以及上述 UVR8 的关键信号传导机制是否保守。在拟南芥 uvr8 无效突变体中异源表达的 SIUVR8 在测试的 UV-B 反应中拯救了 uvr8 突变体，包括下胚轴伸长、UV-B 靶基因表达和花青素积累，表明 SIUVR8 是一种推定的 UV-B 光感受器。此外，作为对 UV-B 的响应，SIUVR8 与植物中的拟南芥 COP1 形成蛋白质复合物，表明保守的信号传导机制。SIUVR8 在植物中表现出与 AtUVR8 相似的光循环，突出了保守的光感受器激活和失活机制。提示保守的信号机制。SIUVR8 在植物中表现出与 AtUVR8 相似的光循环，突出了保守的光感受器激活和失活机制。提示保守的信号机制。SIUVR8 在植物中表现出与 AtUVR8 相似的光循环，突出了保守的光感受器激活和失活机制。