Plants must balance light capture for photosynthesis with protection from potentially harmful ultraviolet radiation (UV). Photoprotection is mediated by concerted action of photoreceptors, but the underlying molecular mechanisms are not fully understood. In this study, we provide evidence that UV RESISTANCE LOCUS 8 (UVR8) UV-B-, phytochrome red-, and cryptochrome blue-light photoreceptors converge on the induction of FERULIC ACID 5-HYDROXYLASE 1 (FAH1) that encodes a key enzyme in the phenylpropanoid biosynthesis pathway, leading to the accumulation of UV-absorbing sinapate esters in Arabidopsis (Arabidopsis thaliana). FAH1 induction depends on the bZIP transcription factors ELONGATED HYPOCOTYL 5 (HY5) and HY5-HOMOLOG (HYH) that function downstream of all three photoreceptors. Noticeably, mutants with hyperactive UVR8 signaling rescue fah1 UV sensitivity. Targeted metabolite profiling suggests that this phenotypic rescue is due to the accumulation of UV-absorbing metabolites derived from precursors of sinapate synthesis, namely coumaroyl-glucose and feruloyl-glucose. Our genetic dissection of the phenylpropanoid pathway combined with metabolomic and physiological analyses show that both sinapate esters and flavonoids contribute to photoprotection with sinapates playing a major role for UV screening. Our findings indicate that photoreceptor-mediated regulation of FAH1 and subsequent accumulation of sinapate “sunscreen” compounds is a key protective mechanism to mitigate damage, preserving photosynthetic performance, and ensuring plant survival under UV.

中文翻译：

---

光感受器诱导的芥子酸合成有助于拟南芥的光保护


植物必须平衡光合作用的光捕获和免受潜在有害的紫外线辐射 (UV) 的影响。光保护是由光感受器的协同作用介导的，但潜在的分子机制尚不完全清楚。在这项研究中，我们提供的证据表明，抗紫外线位点 8 (UVR8) UV-B-、光敏色素红光和隐花色素蓝光感受器会集中诱导阿魏酸 5-羟化酶 1 (FAH1)，该酶编码一种关键酶。苯丙素生物合成途径，导致拟南芥（Arabidopsis thaliana）中吸收紫外线的芥子酸酯的积累。 FAH1 诱导依赖于在所有三个光感受器下游发挥作用的 bZIP 转录因子 ELONGATED HYPOCOTYL 5 (HY5) 和 HY5-HOMOLOG (HYH)。值得注意的是，具有高度活跃的 UVR8 信号传导的突变体可以挽救 fah1 的紫外线敏感性。靶向代谢物分析表明，这种表型拯救是由于芥子酸合成前体（即香豆酰葡萄糖和阿魏酰葡萄糖）衍生的紫外线吸收代谢物的积累所致。我们对苯丙素途径的基因剖析结合代谢组学和生理学分析表明，芥子酸酯和黄酮类化合物都有助于光保护，而芥子酸酯在紫外线屏蔽中发挥着重要作用。我们的研究结果表明，光感受器介导的 FAH1 调节以及随后芥子酸“防晒”化合物的积累是减轻损害、保持光合性能和确保植物在紫外线下生存的关键保护机制。