BACKGROUND Agriculture is highly dependent on climate. Increases in temperature caused by global warming pose challenges for crop production. Heat stress induces oxidative damage to cell membranes and then causes cell death. Plants have developed various responses to elevated temperatures, including hormone signaling pathways and heat shock factors that elevate their thermotolerance. In response to heat stress, the gaseous hormone ethylene is produced through regulation of the expression of signaling-related genes to modulate resource allocation dynamics. For comprehensive understanding of the role of ethylene, this study used an ethylene precursor to analyze the ethylene signaling pathway involved in adjustment of the homeostasis of the antioxidant system and to evaluate heat shock factor expression in rice seedlings under heat stress. RESULTS Levels of cell membrane oxidation and ion leakage were reduced in rice seedlings under heat treatment combined with ethylene precursor treatment, conferring enhanced thermotolerance. Reduction of the fresh weight and chlorophyll a/b ratio in rice seedlings was lower in rice seedlings under heat stress with ethylene precursor treatment than in those under heat stress only. Moreover, reduction of antioxidant response caused by heat stress was ameliorated by treatment with ethylene precursors such as catalase and total peroxidase. Quantitative reverse transcriptase-polymerase chain reaction showed higher expression levels of heat shock factors such as HSFA1a and HSFA2a, c, d, e, and f and ethylene-signaling-related genes such as ethylene insensitive 2, ethylene insensitive-like 1, and ethylene insensitive-like 2 in rice seedlings under heat stress with ethylene precursor treatment than in rice seedlings under heat stress only. CONCLUSION Ethylene-mediated signaling was involved in the reduction of oxidative damage, maintenance of chlorophyll content, and enhancement of thermotolerance in rice seedlings under heat stress. Furthermore, this study revealed heat shock factors and ethylene-signaling-related genes involved in complex network regulation that confers thermotolerance to rice seedlings.

中文翻译：

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乙烯介导的信号传导赋予水稻耐热性，并调节热胁迫下水稻幼苗热激因子的转录水平。

背景技术农业高度依赖气候。由全球变暖引起的温度升高对作物生产构成挑战。热应激诱导对细胞膜的氧化损伤，然后导致细胞死亡。植物对高温产生了多种反应，包括激素信号传导途径和提高其耐热性的热休克因子。响应热应激，通过调节信号相关基因的表达来产生气态激素乙烯，从而调节资源分配动态。为了全面了解乙烯的作用，本研究使用乙烯前体来分析乙烯调节抗氧化剂系统稳态的信号传导途径，并评估热胁迫下水稻幼苗中热激因子的表达。结果热处理和乙烯前驱体处理相结合后，水稻幼苗的细胞膜氧化和离子泄漏水平降低，从而提高了耐热性。用乙烯前体处理的热胁迫下水稻幼苗的鲜重和叶绿素a / b比值的降低要低于仅热胁迫下的幼苗。此外，通过用乙烯前体如过氧化氢酶和总过氧化物酶处理，改善了由热应激引起的抗氧化反应的降低。定量逆转录酶-聚合酶链反应显示较高水平的热休克因子，例如HSFA1a和HSFA2a，c，d，e和f，以及与乙烯信号相关的基因，例如对乙烯不敏感2，对乙烯不敏感1，乙烯前驱物处理的水稻幼苗中的乙烯和类乙烯不敏感样2比仅受热胁迫的水稻幼苗中的乙烯不敏感样2高。结论乙烯介导的信号传导参与了热胁迫下水稻幼苗的氧化损伤的减少，叶绿素含量的维持以及耐热性的提高。此外，这项研究揭示了热激因子和乙烯信号相关基因参与复杂的网络调节，从而赋予水稻幼苗耐热性。