菲胁迫下蒿柳抗氧化系统的响应

目的]研究菲胁迫下活性氧和抗氧化物质的变化规律,探究蒿柳抗氧化系统的防御机制,为提高其对多环芳烃(PAHs)的抗性及加强植物修复的研究提供理论依据。方法]以蒿柳扦插苗为试验材料,采用水培方式,研究其在0、1.0 mg·L^-1菲处理下活性氧、抗氧化酶、抗氧化剂以及丙二醛(MDA)的动态变化,处理时间为16 d。结果]研究表明:(1)菲处理后第4天,H2O2含量和氧自由基(O2^·-)生成速率迅速增加,MDA含量升高,过氧化氢酶(CAT)活性显著上升;第8天超氧化物歧化酶(SOD)和过氧化物酶(POD)活性显著升高;第16天时,H2O2含量下降到与对照无显著差异,O2^·-和MDA的增加量下降。(2)还原型谷胱甘肽(GSH)和谷胱甘肽还原酶(GR)在处理后第4天即迅速上升,谷胱甘肽-S-转移酶(GST)呈缓慢上升趋势。(3)还原型抗坏血酸(AsA)含量在处理后第4天低于对照,但随着处理时间的延长呈上升趋势,在第16天时高于对照。结论]菲胁迫下,O2^·-是造成细胞膜脂过氧化的主要活性氧,SOD活性一直高于对照,但不足以清除增加的O2^·-,CAT和POD的升高可以清除过量的H2O2;GSH是抵御菲胁迫的有效抗氧化剂,并通过GST的催化参与菲的解毒。

Response of Antioxidant System of Salix viminalis under Phenanthrene Stress

Objective] In order to explore the defense mechanism of the antioxidant system of Salix viminalis, the dynamic changes of reactive oxygen and antioxidant substances under phenanthrene stress were observed which can provide new evidence for improving the resistance of plants to polycyclic aromatic hydrocarbon(PAHs) stress and enhancing the phytoremediation potential. Method] The cutting seedlings of S. viminalis were selected as experimental materials, and a 16-day hydroponic experiment with 0 and 1.0 mg·L^-1 phenanthrene concentrations were conducted to study the dynamic changes of reactive oxygen, antioxidant enzymes, antioxidants and malondialdehyde(MDA) contents. Result] The Results showed that:(1) Under phenanthrene treatment, the superoxide anion radical(O2^·-) production and H2 O2 content increased rapidly, then MDA content rose. Catalase(CAT) activity significantly increased on the 4 th day, and the superoxide dismutase(SOD) and peroxidase(POD) activity increased on the 8 th day. On the 16 th day, no significant difference was found in H2 O2 content between the samples treated with phenanthrene and that of the control. Meanwhile, the increment of O2^·-and MDA also slowed down.(2) The contents of reduced glutathione(GSH) and glutathione reductase rose rapidly on the 4 th day under phenanthrene treatment, and the activity of glutathione-s-transferase(GST) increased slowly.(3) Under phenanthrene treatment, the content of ascorbic acid was initially lower than the control group, but higher on the 16 th day as the treatment time continued. Conclusion] Under phenanthrene stress, O2^·-is the main reactive oxygen causing cell membrane lipid peroxidation. SOD activity is always higher than that of the control group, but not enough to eliminate the increased O2^·-. The increase of CAT and POD could eliminate the excessive H2O2. GSH is an effective antioxidant to resist the stress of phenanthrene and participates in the detoxification of phenanthrene through the catalysis of GST.