Lack of Salicylic Acid in Arabidopsis Protects Plants against Moderate Salt Stress
Lack of Salicylic Acid in Arabidopsis Protects Plants against Moderate Salt Stress
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DOI：
10.1515/znc-2009-3-414
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发表时间：
2009-04
期刊：
影响因子：
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通讯作者：
Yang Cao;Zhong-wei Zhang;L. Xue;Jun-bo Du;J. Shang;Fei Xu;S. Yuan;Hong-hui Lin
中科院分区：
文献类型：
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作者：
Yang Cao;Zhong-wei Zhang;L. Xue;Jun-bo Du;J. Shang;Fei Xu;S. Yuan;Hong-hui Lin
先前的研究表明，表达水杨酸羟化酶基因NahG的水杨酸（SA）缺乏转基因拟南芥对中等盐胁迫具有更高的耐受性。SA可能通过诱导活性氧（reactive oxygen species， ROS）增强拟南芥幼苗萌发和生长的胁迫响应。然而，NahG植物更好地适应适度盐胁迫的详细机制在很大程度上是未知的。本研究发现NahG植物在胁迫过程中具有较高的GSH/GSSG（谷胱甘肽/氧化谷胱甘肽）比值和ASA/DHA（抗坏血酸/脱氢抗坏血酸）比值可能是NahG植物具有较强抗逆性的关键原因。NahG植物在自然条件下产生的抗氧化酶活性并不比野生型高，但在胁迫过程中谷胱甘肽还原酶（GR）和脱氢抗坏血酸还原酶（DHAR）活性较高。因此，盐胁迫下NahG植物还原性谷胱甘肽和还原性抗坏血酸含量较高。然而，NahG植物在严重盐胁迫下的适应性并不好。在400 mM NaCl胁迫下，NahG和野生型幼苗的抗氧化酶活性、GSH/GSSG比值和ASA/DHA比值均显著下降。
Previous studies showed that salicylic acid (SA)-deficient transgenic Arabidopsis expressing the salicylate hydroxylase gene NahG had a higher tolerance to moderate salt stress. SA may potentiate the stress response of germination and growth of Arabidopsis seedlings by inducing reactive oxygen species (ROS). However, the detailed mechanism for a better adaption of NahG plants to moderate salt stress is largely unknown. In the present study we found that a higher GSH/GSSG (glutathione/oxidized glutathione) ratio and ASA/DHA (ascorbic acid/dehydroascorbate) ratio in NahG plants during the stress may be the key reason for their stress-tolerance advantage. NahG plants actually could not produce more active antioxidant enzymes than the wild-type ones under natural conditions, but maintain higher activities of glutathione reductase (GR) and dehydroascorbate reductase (DHAR) during the stress. Hereby, the reduced glutathione and reduced ascorbic acid contents are higher in NahG plants under salt stress. However, NahG plants do not adapt better under severe salt stress. All antioxidant enzyme activities, GSH/GSSG ratio and ASA/DHA ratio declined substantively at 400 mM NaCl stress in both NahG and wild-type seedlings.