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作 者 ：陈海燕;崔香菊;陈熙;李建友;张炜

期 刊 ：作物学报 2007年 33卷 07期 页码：1086-1093

关键词：水稻；盐胁迫；三价镧离子；抗氧化酶；质膜H+-ATPase；

Keywords:Oryza sativa, Salt stress, La3+, Antioxidative enzymes, Plasma membrane H+-ATPase,

摘 要 ：用盐敏感的武运粳8号和强耐盐的韭菜青两个粳稻品种，比较了盐胁迫条件下根中抗氧化酶类和质膜H⁺-ATPase活性的变化以及La³⁺对其变化的影响。结果表明，两个品种根中SOD和APX活性无显著区别，但耐盐品种的CAT和POD活性强于盐敏感品种。盐胁迫不同程度地提高了两者抗氧化酶活性。La³⁺对其影响最显著的差异出现在高盐条件下（200~300 mmol L^-1 NaCl），对耐盐品种添加La³⁺可以提高上述4种酶的活力，而对盐敏感品种，La³⁺的作用不明显。对盐敏感品种，盐胁迫导致其质膜H⁺-ATPase活性持续下降，添加La³⁺明显提高其H⁺-ATPase活性，而对耐盐品种，盐胁迫导致其质膜H⁺-ATPase活性呈现先降后升的趋势，La³⁺对其活性影响不大。进一步分析表明，上述H⁺-ATPase活性变化及La³⁺对其影响均发生在转录水平上。据此推测，以上2个品种可能具有完全不同的盐胁迫响应机制。

Abstract:

Plant tolerance to salinity is genetically and physiologically complex. Many mechanisms, such as ion compartmentalization, osmotic regulation and scavenging of reactive oxygen species, have been demonstrated. Among them, anti-oxidative enzymes play an important role in salt tolerant characteristic in plants. In addition, the plasma membrane P-type H⁺-ATPase (EC 3.6.1.3) also involved in the plant response to salinity by regulating the ion homeostasis and so on. Although the relationship between salt stress and anti-oxidative enzymes or PM H⁺-ATPase has been studied widely, the results varied with the different experimental materials. An interesting shortcut is to comparatively study plants naturally adapted to salt versus their more salt-sensitive relatives. In this report, changes in the activities of antioxidative enzymes and plasma membrane H⁺-ATPase from root tips are compared between salt-sensitive and salt-tolerant rice cultivars under NaCl stress, in the presence or absence of La³⁺. The results indicated that CAT and POD activities, but not SOD and APX activities, were higher in salt-tolerant cultivar than in salt-sensitive one. Under NaCl stress, especially in the range of 200–300 mmol L^-1 NaCl, external La³⁺ increased the activities of CAT, SOD, APX, and POD in salt-tolerant rice, but not in salt-sensitive cultivar, which suggests that external La³⁺ can lighten the oxidative damage of rice seedling roots, mainly at high salt concentration range. Plasma membrane H⁺-ATPase activities were suppressed by 30% under NaCl stress in salt-sensitive cultivar, and La³⁺ effectively alleviated such suppression. On the contrary, in salt tolerant cultivar, H⁺-ATPase activity increased by 32% under NaCl treatment, and La³⁺ had little effect on the activities. Semi-quantitative RT-PCR analysis demonstrated that the changes in PM H⁺-ATPase activities and La³⁺ effect under salt stress might occur at transcriptional level. Taken together, the data suggested that in salt-sensitive rice Wuyunjing 8, the root cytosolic Na⁺ concentration seems to be more dependent on the Na⁺ intracellular compartmentation capacity, while in salt-tolerant rice Jiucaiqing, NaCl induces plasma membrane H⁺-ATPase gene expression, indicating that the roots require increased H⁺-electrochemical potential gradient for the maintenance of ion homeostasis for osmotic regulation. In addition, the different effects of La³⁺ on the activities of anti-oxidative enzymes and plasma membrane H⁺-ATPase indicate that there might be completely different salt stress responding mechanisms between salt-sensitive and salt-tolerant rice cultivars.

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