温度对盐胁迫小麦抗氧化机制的影响

Effect of temperature on antioxidation mechanism of wheat (Triticum aestivum L.) seedlings under salt stress

  • 摘要: 本研究以耐盐性不同的8个冬小麦品种为材料, 分别在室温(20 ℃/25 ℃)和接近小麦生产的低温(10 ℃/ 15 ℃)条件下采用溶液培养, 并在苗期进行盐胁迫处理(150 mmol·L-1NaCl), 研究温度和盐胁迫交互作用对耐盐性不同的小麦抗氧化机制的影响。结果表明, 对室温培养的幼苗进行盐胁迫后, 耐盐强的小麦幼苗超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸过氧化酶(APX)活性均显著升高, 并且高于2个耐盐性弱的品种;而耐盐性弱的小麦幼苗盐处理后仅APX活性显著升高, 其活性氧(ROS)累积量和叶片相对电导率均高于耐盐小麦; 抗旱小麦以上指标介于耐盐品种和耐盐性弱的品种中间。低温培养下进行盐胁迫, 谷胱甘肽还原酶(GR)在所有供试品种中均显著升高2~3倍; 耐盐品种仅CAT和APX活性升高, 抗旱品种SOD、POD和APX以及耐盐性弱的品种SOD和POD活性显著提高。由此得出与室温盐胁迫下小麦抗氧化机制的响应不同, 低温盐胁迫条件下, 耐盐小麦SOD和POD酶活性受到抑制, 主要通过提高抗坏血酸?谷胱甘肽循环的两个关键酶APX和GR活性增加对ROS的清除能力, 而抗旱品种和耐盐性弱的品种除GR酶活性显著提高外, SOD和POD对ROS的清除能力均显著增强。在各种抗氧化酶的共同作用下, 耐盐性不同的小麦品种之间ROS累积量和叶片电导率等受伤害指标的差异程度与室温盐胁迫相比减弱。

     

    Abstract: The objective of this study was to elucidate the role of temperature in antioxidation mechanism of eight wheat cultivars differing in salt tolerance. The eight cultivars seedlings were cultured in nutrient solutions at normal (20 ℃ / 25 ℃) and low (10 ℃ / 15 ℃) temperature conditions. The wheat cultivars were set under 150 mmol·L-1 NaCl stress condition for 48 h at the third leaf stage of the seedlings. Then reactive oxygen species (ROS) accumulation, antioxidant enzyme activity and electrolyte leakage (EK) were examined in the eight wheat cultivar seedlings. The results showed that the activities of SOD, POD, CAT and APX in salt-tolerant cultivars increased significantly, and were higher than those of salt sensitive cultivars under salt stress with normal temperature condition. As for salt sensitive cultivars, salt stress only enhanced APX activity. Accumulated ROS and EK in salt sensitive cultivar seedlings were higher than those in salt-tolerant cultivar seedlings. For drought-tolerant cultivars, the values of above parameters were between those of salt-tolerant and salt-sensitive cultivars. Under low temperature, GR activity of all the experimental cultivars increased by 2?3 folds under salt stress compared with that of non-salt-stress treatments. While CAT and APX activities in salt-tolerant cultivars increased significantly, SOD, POD and APX activities in drought-tolerant cultivars obviously improved under salinity stress conditions. Also in salt-sensitive cultivars, SOD and POD activities enhanced markedly under salinity stress conditions. The response of antioxidative enzymes to salt stress under low temperature was different from that under normal temperature. Under low temperature, SOD and POD activities were inhibited in salt-tolerant cultivars seedlings. The excessive ROS induction was stopped mainly by enhanced activities of APX and GR, two key enzymes of ascorbic acid-GSH cycle. For drought-tolerant and salt-sensitive cultivars, salinity stress obviously increased SOD, POD and GR activities, as well as GR activity. As a result of the interaction of antioxidative en-zymes, different scopes of ROS accumulation and EK in wheat cultivars with different levels of salt tolerance reduced under low temperature conditions compared with normal temperature condition.

     

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