• Phosphatidic acid (PA) and hydrogen peroxide (H₂O₂) play roles in regulating plant responses to abiotic stress. The objective of this study was to determine effects of H₂O₂ or PA, individually and interactively, with a H₂O₂ scavenging molecule, N,N'‐dimethylthoiurea (DMTU), on plant tolerance to heat stress in tall fescue (Festuca arundinacea).
• Plants were treated with PA (25 µm), H₂O₂ (5 mm) and PA (25 µm) + DMTU (5 mm) by foliar application and then exposed to heat stress (38/33 °C) or optimal temperature (23/18 °C, day/night) for 28 days.
• Foliar application of PA and H₂O₂ alone resulted in increases in leaf fresh weight, chlorophyll content, photochemical efficiency and cellular membrane stability in plants exposed to heat stress, whereas addition of DMTU suppressed the positive effects of PA. Expression levels of genes encoding the PA synthesizing enzyme, FaPLDδ, were significantly up‐regulated by H₂O₂. Phosphatidic acid‐ or H₂O₂‐enhanced heat tolerance was associated with the activation of stress signalling components (FaCDPK3, FaMPK6, FaMPK3), transcription factors (FaMBF1 and FaHsfA2c) and heat shock proteins (FaHSP18, FaHSP70 and FaHSP90).
• Phosphatidic acid and H₂O₂ may work in coordination to further improve heat tolerance, involving up‐regulation of transcription factors in stress signalling cascades and heat protection systems.

中文翻译：

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磷脂酸和过氧化氢协同提高羊茅的耐热性

• 磷脂酸（PA）和过氧化氢（H ₂ O ₂）在调节植物对非生物胁迫的反应中起作用。这项研究的目的是确定H ₂ O ₂或PA与H ₂ O ₂清除分子N，N'-二甲基硫脲（DMTU）单独和相互作用对高羊茅植物对热胁迫的耐受性（Festuca arundinacea）。
• 通过叶面处理分别用PA（25 µm），H ₂ O ₂（5 m m）和PA（25 µm）+ DMTU（5 m m）处理植物，然后暴露于热胁迫（38/33°C）或28天的最佳温度（23/18°C，白天/晚上）。
• 单独施用PA和H ₂ O ₂导致暴露于热胁迫的植物叶片新鲜重量，叶绿素含量，光化学效率和细胞膜稳定性增加，而添加DMTU则抑制了PA的积极作用。H ₂ O ₂显着上调了编码PA合成酶FaPLDδ的基因的表达水平。磷脂酸或H ₂ O ₂增强的耐热性与胁迫信号成分（FaCDPK3，FaMPK6，FaMPK3），转录因子（FaMBF1和FaHsfA2c）的激活有关）和热激蛋白（FaHSP18，FaHSP70和FaHSP90）。
• 磷脂酸和H ₂ O ₂可能协同作用以进一步提高耐热性，包括上调应激信号级联反应和热保护系统中的转录因子。