外源CaCl2对NaCl胁迫下酸枣幼苗氮代谢的影响
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国家自然科学基金项目(31460057);


Effect of Exogenous CaCl2 on the Nitrogen Metabolism of Sour Jujube Seedlings under NaCl Stress
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    摘要:

    为了研究CaCl2对NaCl胁迫下酸枣幼苗根、茎、叶的氮代谢影响,探索钙缓解幼苗NaCl胁迫的作用途径。该研究以酸枣幼苗为试验材料,检测不同浓度CaCl2(0、5、10、20 mmol/L)对NaCl(150 mmol/L)胁迫下幼苗叶片H2O2、O-·2含量,根、茎、叶中硝酸还原酶(NR)、谷氨酰胺合成酶(GS)、谷氨酸合酶(GOGAT)活性及游离氨基酸、可溶性蛋白、硝态氮含量的影响,并采用主成分分析法筛选出评价CaCl2缓解NaCl胁迫效应的生理指标。结果表明:与NaCl胁迫相比,盐胁迫幼苗叶片的H2O2、O-·2积累量在5、10 mmol/L CaCl2处理下显著减少;GOGAT活性在5、10 mmol/L CaCl2处理下的植株根和茎内以及各浓度 CaCl2处理的叶内均显著升高, GS、NR活性在10、20 mmol/L CaCl2处理的根内和10 mmol/L CaCl2处理的茎内以及5、10、20 mmol/L CaCl2处理的叶内均显著升高;可溶性蛋白含量在5、10、20 mmol/L CaCl2处理的根、茎、叶内均显著升高,游离氨基酸含量在10、20 mmol/L CaCl2处理的根和茎内以及10 mmol/L CaCl2处理的叶内均显著升高,硝态氮含量在10 mmol/L CaCl2处理的根和茎内以及5、10、20 mmol/L CaCl2处理的叶内均显著升高。研究发现,150 mmol/L NaCl胁迫对酸枣幼苗造成明显过氧化伤害,抑制了体内氮代谢;外源CaCl2可通过促进幼苗根和茎内GS/GOGAT循环对NH4+的同化作用,提高叶片NR活性,加快硝态氮的转化速率,从而增强幼苗对NaCl胁迫的适应性,并以10 mmol/L CaCl2处理缓解效果最佳;游离氨基酸、GOGAT、NR可以作为CaCl2缓解幼苗NaCl胁迫伤害的评价指标。

    Abstract:

    The objectives of this experiment were to study the effects of CaCl2 concentration on N metabolism in roots, stems and leaves of sour jujube under NaCl stress and to determine the ability of exogenous Ca to alleviate NaCl stress in sour jujube seedlings. The jujube seedlings were used as test materials to measured hydrogen peroxide (H2O2) and super oxide (O-·2) concentrations in the leaves by different concentrations of CaCl2 (0, 5, 10 and 20 mmol/L) under NaCl stress (150 mmol/L). The activities of nitrate reductase (NR), glutamine synthetase (GS), and glutamate synthase (GOGAT) and the concentrations of free amino acid, protein and NO3N were measured in roots, stems, and leaves. Principal component analysis was used to select the best physiological indexes for evaluating the ability of CaCl2 to alleviate NaCl stress in sour jujube seedlings. The results showed that 5 and 10 mmol/L CaCl2 significantly reduced H2O2 and O-·2 concentrations in the leaves of NaClstressed sour jujube seedlings. The 5 and 10 mmol/L CaCl2 treatments significantly increased GOGAT activity in roots and stems. All of the CaCl2 treatments significantly increased GOGAT activity in leaves. Leaf GS and NR activities were significantly increased by all of the CaCl2 treatments. Root GS and NR activities were significantly increased by 10 and 20 mmol/L CaCl2, whereas 5 mmol/L CaCl2 had no significant effect. Stem GS and NR activities were increased only by 10 mmol/L CaCl2. All of the CaCl2 treatments significantly increased protein contents in roots, stems, and leaves. The 10 and 20 mmol/L CaCl2 treatments increased free amino acid contents in roots and stems, whereas only the 10 mmol/L CaCl2 treatment significantly increased free amino acids in leaves. The 10 mmol/L CaCl2 treatment significantly increased NO3N concentrations in roots and stems. All three CaCl2 treatments increased NO3N concentrations in leaves. The 150 mmol/L NaCl stress treatment caused significant peroxidative damage to wild jujube seedlings and inhibited N metabolism. Exogenous CaCl2 helped the sour jujube seedlings adapt to NaCl stress by promoting the assimilation of NH4+ via the GS/GOGAT cycle in roots and stems and by increasing NR activity and regulating NO3N transformation rates. The results showed that 10 mmol/L CaCl2 was the most effective treatment for alleviating NaCl stress in sour jujube seedlings. The GOGAT activity, NR activity, and free amino acid concentrations can be used to evaluate the ability of CaCl2 to alleviate NaCl stress in sour jujube.

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王晓丽,鲁晓燕,涂文文,等.外源CaCl2对NaCl胁迫下酸枣幼苗氮代谢的影响[J].西北植物学报,2018,38(9):1683-1691

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  • 在线发布日期: 2018-10-23
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