College of Life Sciences, Sichuan Agricultural University, Ya'an 625014, China.
College of Resources Science and Technology, Sichuan Agricultural University, Chengdu 611130, China.
Int J Mol Sci. 2020 Feb 12;21(4):1229. doi: 10.3390/ijms21041229.
Salicylic acid (SA) is considered to play an important role in plant responses to environmental stresses. However, the detailed protective mechanisms in photosynthesis are still unclear. We therefore explored the protective roles of SA in photosystem II (PSII) in under high light. The results demonstrated that 3 h of high light exposure resulted in a decline in photochemical efficiency and the dissipation of excess excitation energy. However, SA application significantly improved the photosynthetic capacity and the dissipation of excitation energy under high light. Western blot analysis revealed that SA application alleviated the decrease in the levels of D1 and D2 protein and increased the amount of Lhcb5 and PsbS protein under high light. Results from photoinhibition highlighted that SA application could accelerate the repair of D1 protein. Furthermore, the phosphorylated levels of D1 and D2 proteins were significantly increased under high light in the presence of SA. In addition, we found that SA application significantly alleviated the disassembly of PSII-LHCII super complexes and LHCII under high light for 3 h. Overall, our findings demonstrated that SA may efficiently alleviate photoinhibition and improve photoprotection by dissipating excess excitation energy, enhancing the phosphorylation of PSII reaction center proteins, and preventing the disassembly of PSII super complexes.
水杨酸（SA）被认为在植物对环境胁迫的响应中发挥重要作用。然而，其在光合作用中的详细保护机制仍不清楚。因此，我们在高光下探索了 SA 对光系统 II（PSII）的保护作用。结果表明，高光暴露 3 小时导致光化学效率下降和过剩激发能的耗散。然而，SA 的应用显著提高了高光下的光合作用能力和激发能的耗散。Western blot 分析表明，SA 的应用缓解了高光下 D1 和 D2 蛋白水平的下降，并增加了 Lhcb5 和 PsbS 蛋白的含量。光抑制的结果表明，SA 的应用可以加速 D1 蛋白的修复。此外，在存在 SA 的情况下，高光下 D1 和 D2 蛋白的磷酸化水平显著增加。此外，我们发现 SA 的应用显著缓解了高光下 3 小时 PSII-LHCII 超复合物和 LHCII 的解体。总的来说，我们的研究结果表明，SA 可以通过耗散过剩的激发能、增强 PSII 反应中心蛋白的磷酸化以及防止 PSII 超复合物的解体，有效地缓解光抑制并提高光保护作用。
