State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Forestry, Guangxi University, Nanning, 530004, China; Guangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning, 530004, China.
Guangxi Key Laboratory of Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning, 530004, China; Guangxi Dongmen Forest Farm, Chongzuo, 532108, China.
Plant Physiol Biochem. 2024 Jul;212:108715. doi: 10.1016/j.plaphy.2024.108715. Epub 2024 May 12.
Light plays a pivotal role in regulating anthocyanin biosynthesis in plants, and the early light-responsive signals that initiate anthocyanin biosynthesis remain to be elucidated. In this study, we showed that the anthocyanin biosynthesis in Eucalyptus is hypersensitive to increased light intensity. The combined transcriptomic and metabolomic analyses were conducted on Eucalyptus leaves after moderate (ML; 100 μmol m s) and high (HL; 300 μmol m s) light intensity treatments. The results identified 1940, 1096, 1173, and 2756 differentially expressed genes at 6, 12, 24, and 36 h after HL treatment, respectively. The metabolomic results revealed the primary anthocyanin types, and other differentially accumulated flavonoids and phenylpropane intermediates that were produced in response to HL, which well aligned with the transcriptome results. Moreover, biochemical analysis showed that HL inhibited peroxidase activity and increased the ROS level in Eucalyptus leaves. ROS depletion through co-application of the antioxidants rutin, uric acid, and melatonin significantly reduced, and even abolished, anthocyanin biosynthesis induced by HL treatment. Additionally, exogenous application of hydrogen peroxide efficiently induced anthocyanin biosynthesis within 24 h, even under ML conditions, suggesting that ROS played a major role in activating anthocyanin biosynthesis. A HL-responsive MYB transcription factor EgrMYB113 was identified to play an important role in regulating anthocyanin biosynthesis by targeting multiple anthocyanin biosynthesis genes. Additionally, the results demonstrated that gibberellic acid and sugar signaling contributed to HL-induced anthocyanin biosynthesis. Conclusively, these results suggested that HL triggers multiple signaling pathways to induce anthocyanin biosynthesis, with ROS acting as indispensable mediators in Eucalyptus.
光是调节植物类黄酮生物合成的关键因素，而启动类黄酮生物合成的早期光响应信号仍有待阐明。在这项研究中，我们表明桉树的类黄酮生物合成对光照强度的增加高度敏感。在中光（ML；100 μmol m s）和高光（HL；300 μmol m s）强度处理后，对桉树叶片进行了联合转录组学和代谢组学分析。结果分别在 HL 处理后 6、12、24 和 36 h 鉴定出 1940、1096、1173 和 2756 个差异表达基因。代谢组学结果揭示了主要的类黄酮类型以及其他响应 HL 产生的差异积累的类黄酮和苯丙烷中间产物，与转录组结果很好地吻合。此外，生化分析表明 HL 抑制过氧化物酶活性并增加桉树叶片中的 ROS 水平。抗氧化剂芦丁、尿酸和褪黑素的共同应用通过耗竭 ROS，显著降低甚至消除 HL 处理诱导的类黄酮生物合成。此外，外源 H 2 O 2 可在 24 h 内有效诱导类黄酮生物合成，即使在 ML 条件下也是如此，表明 ROS 在激活类黄酮生物合成中起主要作用。鉴定出一个 HL 响应的 MYB 转录因子 EgrMYB113 通过靶向多个类黄酮生物合成基因在调节类黄酮生物合成中发挥重要作用。此外，结果表明赤霉素和糖信号参与了 HL 诱导的类黄酮生物合成。总之，这些结果表明 HL 触发了多种信号通路来诱导类黄酮生物合成，ROS 是桉树中不可或缺的介质。
