• Salinity is a severe threat to crop growth, development and even to world food sustainability. Plant possess natural antioxidant defense tactics to mitigate salinity‐induced oxidative stress. Phenolic compounds are non‐enzymatic antioxidants with specific roles in protecting plant cells against stress‐mediated reactive oxygen species (ROS) generation. Coumarin (COU) is one of these compounds, however, to date, little is known about antioxidative roles of exogenous COU in enhancing plant tolerance mechanisms under salt stress.
• The involvement of COU in increasing tomato salt tolerance was examined in the present study using COU as a pre‐treatment at 20 or 30 µM for 2 days against salt stress (100 or 160 NaCl; 5 days). The COU‐mediated stimulation of plant antioxidant defence and glyoxalase systems to suppress salt‐induced ROS and methylglyoxal (MG) toxicity, respectively, were the main hypotheses examined in the present study.
• Addition of COU suppressed salt‐induced excess accumulation of ROS and MG, and significantly reduced membrane damage, lipid peroxidation and Na⁺ toxicity. These results demonstrate COU‐improved plant growth, biomass content, photosynthetic pigment content, water retention and mineral homeostasis upon imposition of salinity.
• Finally, this present study suggests that COU has potential roles as a phytoprotectant in stimulating plant antioxidative mechanisms and improving glyoxalase enzyme activity under salinity stress.

中文翻译：

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香豆素通过增强抗氧化剂防御，乙二醛酶系统和离子稳态来提高番茄对盐分的耐受性

• 盐分严重威胁作物的生长，发育，甚至对世界粮食可持续性。植物具有天然的抗氧化剂防御策略，可减轻盐分诱导的氧化胁迫。酚类化合物是非酶类抗氧化剂，在保护植物细胞免受胁迫介导的活性氧（ROS）生成方面具有特定作用。香豆素（COU）是这些化合物之一，然而，迄今为止，关于盐胁迫下外源COU在增强植物耐受性机制中的抗氧化作用知之甚少。
• 在本研究中，使用COU作为20或30 µM的抗盐胁迫（100或160 NaCl； 5天）的预处理，研究了COU在增加番茄耐盐性中的作用。COU介导的植物抗氧化剂防御和乙二醛酶系统刺激分别抑制盐诱导的ROS和甲基乙二醛（MG）毒性是本研究中检验的主要假设。
• 添加COU可以抑制盐诱导的ROS和MG的过量积累，并显着减少膜损伤，脂质过氧化和Na ⁺毒性。这些结果表明，在施加盐分后，COU可以改善植物的生长，生物量，光合色素的含量，保水率和矿物质的稳态。
• 最后，本研究表明，在盐分胁迫下，COU在刺激植物抗氧化机制和改善乙二醛酶活性方面具有潜在的植物保护作用。