Ethylene and salicylic acid control glutathione biosynthesis in ozone-exposed Arabidopsis thaliana.
Ethylene and salicylic acid control glutathione biosynthesis in ozone-exposed Arabidopsis thaliana.
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DOI：
10.1111/j.1399-3054.2009.01220.x
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发表时间：
2009-07
影响因子：
6.4
通讯作者：
Seiji Yoshida;M. Tamaoki;Motohide Ioki;D. Ogawa;Yuko Sato;M. Aono;A. Kubo;S. Saji;H. Saji;S. Satoh;N. Nakajima
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文献类型：
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作者：
Seiji Yoshida;M. Tamaoki;Motohide Ioki;D. Ogawa;Yuko Sato;M. Aono;A. Kubo;S. Saji;H. Saji;S. Satoh;N. Nakajima
臭氧产生活性氧物种，并诱导植物激素的合成，包括乙烯和水杨酸。这些植物激素充当信号分子，增强细胞对臭氧暴露的反应死亡。然而，一些研究表明，乙烯和水杨酸反而可以降低臭氧诱导的细胞死亡的幅度。因此，我们研究了乙烯和水杨酸对臭氧的防御作用。与野生型Col-0不同，缺乏乙烯信号转导(Ein2)或水杨酸生物合成(Sid2)的拟南芥突变体产生高水平的超氧化物并表现出明显的叶片伤害，表明乙烯和水杨酸可以减轻臭氧破坏。基因芯片分析表明，乙烯和水杨酸缺陷影响了谷胱甘肽(GSH)的代谢。而ein2和sid2突变体在臭氧暴露后6h的Col-0中GSH含量明显升高，表明GSH水平受乙烯或水杨酸信号的影响。我们利用与GSH代谢相关的基因，通过实时聚合酶链式反应进行基因表达分析。在Col-0中，γ-谷氨酰半胱氨酸合成酶(GSH1)、谷胱甘肽合成酶(GSH2)和谷胱甘肽还原酶1(GR1)的表达被正常诱导，但在ein2和sid2中的表达水平要低得多。Ein2和Sid2的GSH1和GSH2的酶活性显著低于Col-0。此外，在ein2和sid2中观察到的臭氧诱导的叶片伤害可以通过人为提高GSH含量来缓解。我们的结果表明，乙烯和水杨酸通过增加GSH的从头生物合成来保护臭氧诱导的叶片伤害。
Ozone produces reactive oxygen species and induces the synthesis of phytohormones, including ethylene and salicylic acid. These phytohormones act as signal molecules that enhance cell death in response to ozone exposure. However, some studies have shown that ethylene and salicylic acid can instead decrease the magnitude of ozone-induced cell death. Therefore, we studied the defensive roles of ethylene and salicylic acid against ozone. Unlike the wild-type, Col-0, Arabidopsis mutants deficient in ethylene signaling (ein2) or salicylic acid biosynthesis (sid2) generated high levels of superoxide and exhibited visible leaf injury, indicating that ethylene and salicylic acid can reduce ozone damage. Macroarray analysis suggested that the ethylene and salicylic acid defects influenced glutathione (GSH) metabolism. Increases in the reduced form of GSH occurred in Col-0 6 h after ozone exposure, but little GSH was detected in ein2 and sid2 mutants, suggesting that GSH levels were affected by ethylene or salicylic acid signaling. We performed gene expression analysis by real-time polymerase chain reaction using genes involved in GSH metabolism. Induction of gamma-glutamylcysteine synthetase (GSH1), glutathione synthetase (GSH2), and glutathione reductase 1 (GR1) expression occurred normally in Col-0, but at much lower levels in ein2 and sid2. Enzymatic activities of GSH1 and GSH2 in ein2 and sid2 were significantly lower than in Col-0. Moreover, ozone-induced leaf damage observed in ein2 and sid2 was mitigated by artificial elevation of GSH content. Our results suggest that ethylene and salicylic acid protect against ozone-induced leaf injury by increasing de novo biosynthesis of GSH.