高浓度镉、锌及其复合作用对烟草抗氧化系统的影响

采用水培方法,研究高浓度镉(0.1 mmol·L^-1 Cd²⁺)、锌(0.15 mmol·L^-1 Zn²⁺)及其复合作用(0.1 mmol·L^-1 Cd²⁺+0.15 mmol·L^-1Zn²⁺)对烟草种子的萌发率、幼苗叶片活性氧(ROS)水平、抗氧化物浓度、抗氧化酶活性及膜脂过氧化程度的影响.结果表明: 单因子条件下,与对照相比,高浓度镉、锌处理烟草种子萌发率降低;叶片超氧自由基(O₂^-· )产生速率与过氧化氢(H₂O₂)含量升高;过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)、脱氢抗化血酸还原酶(DHAR)、单脱氢抗坏血酸还原酶(MDAR)和谷胱甘肽还原酶(GR)活性升高;谷胱甘肽(GSH)含量及其与氧化型谷胱甘肽比值(GSH/GSSG)下降;丙二醛(MDA)含量升高.与镉、锌单因子处理相比,镉、锌复合处理的烟草种子萌发率显著升高;O₂^-· 产生速率、H₂O₂和MDA含量降低;CAT、APX、MDAR活性在处理末期升高.镉、锌胁迫对烟草可造成生理水平上的损伤,且毒性效应随着处理时间的延长而增强.镉、锌复合作用可缓解镉、锌单因子胁迫对烟草幼苗的毒害.

Effects of elevated Cd,Zn and their combined effects on antioxidant system of tobacco

A solution culture was conducted to study the effects of elevated Cd and/or Zn ions (0.1 mmol·L^-1 Cd²⁺, 0.15 mmol·L^-1 Zn²⁺, 0.1 mmol·L^-1 Cd²⁺+0.15 mmol·L^-1Zn²⁺) on seed germination rate and reactive oxygen species (ROS) level, antioxidants contents, antioxidant enzyme activities and product of membrane lipid peroxidation in tobacco seedling leaves. The results showed that compared to control, the seed germination rate decreased under elevated level of Cd²⁺or Zn²⁺, the superoxide radical (O₂^-· ) generation rate and hydrogen peroxide (H₂O₂) content in tobacco seedlings increased, the activities of catalase (CAT), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDAR), and glutathione reductase (GR) increased, content of glutathione (GSH) and GSH/GSSG (oxidized glutathione) ratio decreased, and malondialdehyde (MDA) content increased. Compared to elevation of the level of only Cd²⁺ or Zn²⁺, the seed germination rate under elevation of both Cd²⁺ and Zn²⁺ levels was enhanced significantly; O₂^-· generation rate, contents of H₂O₂ and MDA decreased; CAT, APX and MDAR activities increased in the last stage of Cd²⁺ and Zn²⁺ exposure. Heavy metal Cd²⁺ or Zn²⁺ could induce the physiological injury to tobacco seedlings, and the toxic effects increased with prolonged stress time. The combined treatment of Cd and Zn could alleviate the toxicity of single stress on tobacco seedlings.