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引用本文:吴娟,施国新,黄敏,夏海威,乔绪强,汪鹏合.外源钙对菹草(Potamogeton crispus L.)汞胁迫的影响效应.湖泊科学,2014,26(3):423-431. DOI:10.18307/2014.0313
WU Juan,SHI Guoxin,HUANG Min,XIA Haiwei,QIAO Xuqiang,WANG Penghe.Effects of exogenous calcium on resistance of Potamogeton crispus L. to mercury stress. J. Lake Sci.2014,26(3):423-431. DOI:10.18307/2014.0313
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外源钙对菹草(Potamogeton crispus L.)汞胁迫的影响效应
吴娟, 施国新, 黄敏, 夏海威, 乔绪强, 汪鹏合
南京师范大学生命科学学院, 江苏省生物多样性与生物技术重点实验室, 南京 210023
摘要:
以组织培养的菹草无菌苗为实验材料,研究了外源Ca(NO3)2的添加对汞(Hg)胁迫下菹草体内Hg积累、矿质元素、光合色素、活性氧、丙二醛(MDA)、维生素C(VC)、维生素E(VE)、谷胱甘肽(GSH)以及多胺(PAs)代谢产生的影响效应机制.结果表明:(1)Hg胁迫下,菹草体内Hg大量积累,达165.79μg/g(FW),并伴随矿质元素P、K、Fe、Mg和Na含量的明显降低.外源Ca(NO3)2的添加很大程度上可抑制菹草体内Hg积累,使其降至110.15μg/g(FW),并减轻Hg胁迫所造成的元素失衡;(2)Hg胁迫使菹草体内光合色素含量及叶绿素a/b值大幅降低,并诱导积累大量超氧阴离子、过氧化氢及MDA,同时VC、VE和GSH含量显著提升.外源Ca(NO3)2的添加则减缓了菹草体内光合色素的分解,降低活性氧水平,减轻了膜脂过氧化程度,更使VC、VE及GSH含量在一定程度上恢复到正常水平;(3)Hg胁迫下,伴随着多胺氧化酶、二胺氧化酶和精氨酸脱羧酶活性的显著提升以及鸟氨酸脱羧酶活性的降低,导致菹草体内腐胺(Put)、精胺(Spm)含量明显降低,亚精胺(Spd)含量及游离态(Spd+Spm)/Put比值轻微增加.而外源Ca(NO3)2添加后,菹草通过调节体内PAs代谢酶活性,改变了Hg胁迫下PAs含量变化,主要表现为Put、Spm含量回升显著,游离态(Spd+Spm)/Put比值进一步升高.综上所述,外源Ca的添加可抑制Hg的吸收并参与调节多胺代谢,通过内源多胺含量的改变抑制了植物体内活性氧的积累、膜脂过氧化、光合色素及抗氧化物质的分解,增强菹草无菌苗对重金属Hg的耐受力,对减轻植物Hg胁迫有重要作用.
关键词:  菹草    外源钙  氧化胁迫  多胺
DOI:10.18307/2014.0313
分类号:
基金项目:江苏高校优势学科建设工程项目(164320H106)资助
Effects of exogenous calcium on resistance of Potamogeton crispus L. to mercury stress
WU Juan, SHI Guoxin, HUANG Min, XIA Haiwei, QIAO Xuqiang, WANG Penghe
Jiangsu Key Lab of Biodiversity and Biotechnology, College of Life Science, Nanjing Normal University, Nanjing 210023, P. R. China
Abstract:
Sterile seedlings of Potamogeton crispus L. were cultured by tissue culture technique, and were used as experimental materials. In this study, the effects of exogenous calcium (Ca) application on mercury (Hg) accumulation, mineral nutrition, photosynthetic pigments, superoxide anion, hydrogen peroxide, malondialdehyde (MDA), vitamin C and E, glutathione (GSH) and polyamines metabolism of the tested plants under the stress of 1.5 μmol/L Hg stress were investigated. The results demonstrated that, (1) Hg stress induced a substantial accumulation of Hg at 165.79 μg/g(FW) and resulted in serious imbalance of nutrient elements, such as inhibiting the absorption of P, K, Fe, Mg and Na, whereas exogenous Ca significantly reduced the accumulation of Hg by 66.4% and effectively reduced the Hg-induced imbalance of nutrient elements in Potamogeton crispus L.. (2) Hg treatment severely reduced chlorophyll concentration and chlorophyll-a/b ratio, and raised O2·-generation rate, H2O2 and MDA contents, while increased the levels of VC, VE and GSH. Application of exogenous Ca markedly retarded the degradation of photosynthetic pigments and also significantly improved the levels of antioxidant capacity in the tested plants. (3) Hg treatment enhanced polyamine oxidase, diamine oxidase and arginine decarboxylase activities. Furthermore, reduced ornithine decarboxylase resulted in the decrease of putrescine (Put) and spermine (Spm) and in, slightly, the increase of spermidine (Spd) content. Exogenous Ca altered polyamines content of Hg stress by modulating polyamines metabolizing enzymes activities, mainly presented as significant increase in Put and Spm contents, and further increased the ratio of free (Spd + Spm)/Put. These results indicated that the supplement of exogenous Ca relieved the phytotoxicity of Hg to Potamogeton crispus L. by depressing the accumulation of Hg and involving in regulation of a series of physiological and biochemical mechanisms, particularly polyamines metabolism.
Key words:  Potamogeton crispus L.  mercury  exogenous calcium  oxidative stress  polyamines
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