Melatonin (MT) can protect plants against abiotic stress. In order to explore whether melatonin can improve photosynthetic function under NaCl stress, Solanum lycopersicum L. cv. Liaoyuanduoli were exposed to 150 mmol L⁻¹ NaCl stress with or without pretreatment with 150 μmol L⁻¹ melatonin. The results showed that NaCl stress can lead to reduced chlorophyll content, lower photosynthetic function, increased reaction oxygen species (ROS) levels, and decreased PSII activity. These changes were mainly due to the reduction in oxygen-evolving complex (OEC) activity on the donor side of PSII and the blockage of electron transfer from Q_A to Q_B on receptor side of PSII. The donor side of PSII was more sensitive to NaCl stress relative to the receptor side of PSII. Interestingly, application of MT enhanced tomato NaCl tolerance. MT reduced the production of ROS by balancing the distribution of photosynthetic electron flux, facilitated the repair of PSII by maintaining the abundance of Psb O and D1, and promoting the ability of the donor and acceptor sides of PSII to deliver electrons. MT also enhanced the scavenging ability of ROS by stimulating the activity of enzymes involved in the AsA-GSH cycle.

褪黑激素（MT）可以保护植物免受非生物胁迫。为了探索褪黑素是否可以改善NaCl胁迫下的光合作用，Solaum lycopersicum L. cv。不论是否使用150μmolL ^-1褪黑素预处理，辽源多里都暴露于150 mmol L ^-1 NaCl胁迫下。结果表明，NaCl胁迫可导致叶绿素含量降低，光合功能降低，反应氧（ROS）水平升高和PSII活性降低。这些变化主要是由于PSII供体侧的放氧复合物（OEC）活性降低以及电子从Q _A到Q _B的传递受阻在PSII的受体侧 相对于PSII的受体侧，PSII的供体侧对NaCl胁迫更为敏感。有趣的是，MT的应用增强了番茄对NaCl的耐受性。MT通过平衡光合电子通量的分布来减少ROS的产生，通过保持Psb O和D1的丰度促进PSII的修复，并提高PSII供体和受体侧传递电子的能力。MT还通过刺激与AsA-GSH循环有关的酶的活性来增强ROS的清除能力。