Glutathione is essential for plant tolerance to arsenic but few studies have focused on the coordination between the enzymes involved in its metabolism. We exposed Pistia stratiotes to four treatments (control, 5, 10 and 20 µM AsIII) for 24 h to evaluate the role of glutathione metabolism in arsenic response and determined the arsenic uptake, growth, membrane integrity, glutathione concentration and enzyme activities (γ-glutamyl-cysteine synthetase, glutathione reductase, glutathione peroxidase, and glutathione-S-transferase). Despite absorbing high concentrations of AsIII, plants maintained growth and cell membrane integrity when exposed to concentrations of up to 10 µM AsIII. The maintenance of these parameters involved glutathione concentration increase due to an increase in its biosynthetic pathway (higher γ-glutamyl-cysteine synthetase). In addition, an increase in the activity of glutathione reductase, glutathione peroxidase and glutathione-S-transferase also contributed to the conserve the cellular homeostasis. However, at the concentration of 20 µM AsIII, the high toxicity of AsIII affected glutathione concentration and glutathione metabolizing enzymes activities, which resulted in drastic decrease in growth and damage to cell membranes. These results showed that not only the glutathione concentration but also the coordination of the enzymes involved in the synthesis, oxidation and reduction pathways of glutathione is essential for AsIII tolerance.

中文翻译：

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雌蕊中谷胱甘肽和谷胱甘肽代谢酶的参与对砷的耐受性分级。

谷胱甘肽对于植物对砷的耐受性是必不可少的，但是很少有研究集中在参与其代谢的酶之间的协调上。我们将Pistia纹层暴露于4种处理（对照，5、10和20 µM AsIII）中24小时，以评估谷胱甘肽代谢在砷反应中的作用，并确定砷的吸收，生长，膜完整性，谷胱甘肽浓度和酶活性（γ-谷氨酰半胱氨酸合成酶，谷胱甘肽还原酶，谷胱甘肽过氧化物酶和谷胱甘肽-S-转移酶）。尽管吸收了高浓度的AsIII，当暴露于浓度高达10 µM的AsIII时，植物仍能保持生长和细胞膜完整性。这些参数的维持涉及谷胱甘肽浓度的增加，这是由于其生物合成途径的增加（较高的γ-谷氨酰-半胱氨酸合成酶）。另外，谷胱甘肽还原酶，谷胱甘肽过氧化物酶和谷胱甘肽-S-转移酶活性的增加也有助于保持细胞稳态。但是，当AsIII浓度为20 µM时，AsIII的高毒性会影响谷胱甘肽浓度和谷胱甘肽代谢酶的活性，从而导致生长急剧下降并破坏细胞膜。这些结果表明，不仅谷胱甘肽浓度，而且参与谷胱甘肽的合成，氧化和还原途径的酶的配位对于AsIII耐受性都是必不可少的。AsIII的高毒性影响了谷胱甘肽的浓度和谷胱甘肽代谢酶的活性，从而导致生长急剧下降并破坏细胞膜。这些结果表明，不仅谷胱甘肽浓度，而且参与谷胱甘肽的合成，氧化和还原途径的酶的配位对于AsIII耐受性都是必不可少的。AsIII的高毒性影响了谷胱甘肽的浓度和谷胱甘肽代谢酶的活性，从而导致生长急剧下降并破坏细胞膜。这些结果表明，不仅谷胱甘肽浓度，而且参与谷胱甘肽的合成，氧化和还原途径的酶的配位对于AsIII耐受性都是必不可少的。