Glutathione Deficiency of the Arabidopsis Mutant pad2-1 Affects Oxidative Stress-Related Events, Defense Gene Expression, and the Hypersensitive Response
Glutathione Deficiency of the Arabidopsis Mutant pad2-1 Affects Oxidative Stress-Related Events, Defense Gene Expression, and the Hypersensitive Response
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DOI：
10.1104/pp.111.182667
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发表时间：
2011-12-01
期刊：
影响因子：
7.4
通讯作者：
Poinssot, Benoit
中科院分区：
文献类型：
--
作者：
Dubreuil-Maurizi, Carole;Vitecek, Jan;Poinssot, Benoit
拟南芥（Arabidopsis thaliana）植物抗毒素缺陷突变体pad2 - 1显示出对广泛的病原体和草食性昆虫的增强的易感性，这与camalexin、吲哚硫代葡萄糖苷和水杨酸（SA）的产生缺陷相关。pad2 - 1突变位于编码谷胱甘肽生物合成第一种酶的谷氨酸-半胱氨酸连接酶（GCL）基因中。虽然pad2 - 1谷胱甘肽缺乏不是由GCL转录物的减少引起的，但GCL蛋白水平的分析显示pad2 - 1植物仅含有野生型蛋白量的48%。与野生型相比，GCL的氧化形式在pad2 - 1中占主导地位，这表明了不同的氧化还原环境。GRX1-roGFP 2的表达证实了这一发现，表明细胞溶质谷胱甘肽氧化还原电位在pad2 - 1中的负性显著降低。氧化应激相关基因表达的分析表明，在pad2 - 1的谷胱甘肽还原酶，谷胱甘肽-S-转移酶，和乙酰化爆发氧化酶同源物D在响应卵菌芸苔疫霉较高的转录积累。有趣的是，pad2 - 1中的寡聚半乳糖醛酸苷诱导揭示了较低的质膜去极化，发现其在受损的过氧化氢产生的上游起作用。在病原体感染期间也观察到这种受损的过氧化氢产生，并且与pad2 - 1中降低的过敏反应相关。此外，病原体触发的异分支酸合酶1基因（编码SA-生物合成酶异分支酸合酶）表达的缺乏被鉴定为pad2 - 1中SA缺乏的原因。总之，我们的研究结果表明，pad2 - 1突变与GCL蛋白的减少有关，由此产生的谷胱甘肽缺乏对抗病性的重要过程产生负面影响。
The Arabidopsis (Arabidopsis thaliana) phytoalexin-deficient mutant pad2-1 displays enhanced susceptibility to a broad range of pathogens and herbivorous insects that correlates with deficiencies in the production of camalexin, indole glucosinolates, and salicylic acid (SA). The pad2-1 mutation is localized in the GLUTAMATE-CYSTEINE LIGASE (GCL) gene encoding the first enzyme of glutathione biosynthesis. While pad2-1 glutathione deficiency is not caused by a decrease in GCL transcripts, analysis of GCL protein level revealed that pad2-1 plants contained only 48% of the wild-type protein amount. In contrast to the wild type, the oxidized form of GCL was dominant in pad2-1, suggesting a distinct redox environment. This finding was corroborated by the expression of GRX1-roGFP2, showing that the cytosolic glutathione redox potential was significantly less negative in pad2-1. Analysis of oxidative stress-related gene expression showed a higher transcript accumulation in pad2-1 of GLUTATHIONE REDUCTASE, GLUTATHIONE-S-TRANSFERASE, and RESPIRATORY BURST OXIDASE HOMOLOG D in response to the oomycete Phytophthora brassicae. Interestingly, oligogalacturonide elicitation in pad2-1 revealed a lower plasma membrane depolarization that was found to act upstream of an impaired hydrogen peroxide production. This impaired hydrogen peroxide production was also observed during pathogen infection and correlated with a reduced hypersensitive response in pad2-1. In addition, a lack of pathogen-triggered expression of the ISOCHORISMATE SYNTHASE1 gene, coding for the SA-biosynthetic enzyme isochorismate synthase, was identified as the cause of the SA deficiency in pad2-1. Together, our results indicate that the pad2-1 mutation is related to a decrease in GCL protein and that the resulting glutathione deficiency negatively affects important processes of disease resistance.