Plant Genetic Engineering and Molecular Biotechnology Lab, Department of Biotechnology, Periyar University, Salem, 636 011, TN, India.
Environ Sci Pollut Res Int. 2015 Mar;22(6):4597-608. doi: 10.1007/s11356-014-3576-2. Epub 2014 Oct 18.
Mercury heavy metal pollution has become an important environmental problem worldwide. Accumulation of mercury ions by plants may disrupt many cellular functions and block normal growth and development. To assess mercury heavy metal toxicity, we performed an experiment focusing on the responses of Eichhornia crassipes to mercury-induced oxidative stress. E. crassipes seedlings were exposed to varying concentrations of mercury to investigate the level of mercury ions accumulation, changes in growth patterns, antioxidant defense mechanisms, and DNA damage under hydroponics system. Results showed that plant growth rate was significantly inhibited (52 %) at 50 mg/L treatment. Accumulation of mercury ion level were 1.99 mg/g dry weight, 1.74 mg/g dry weight, and 1.39 mg/g dry weight in root, leaf, and petiole tissues, respectively. There was a decreasing trend for chlorophyll a, b, and carotenoids with increasing the concentration of mercury ions. Both the ascorbate peroxidase and malondialdehyde contents showed increased trend in leaves and roots up to 30 mg/L mercury treatment and slightly decreased at the higher concentrations. There was a positive correlation between heavy metal dose and superoxide dismutase, catalase, and peroxidase antioxidative enzyme activities which could be used as biomarkers to monitor pollution in E. crassipes. Due to heavy metal stress, some of the normal DNA bands were disappeared and additional bands were amplified compared to the control in the random amplified polymorphic DNA (RAPD) profile. Random amplified polymorphic DNA results indicated that genomic template stability was significantly affected by mercury heavy metal treatment. We concluded that DNA changes determined by random amplified polymorphic DNA assay evolved a useful molecular marker for detection of genotoxic effects of mercury heavy metal contamination in plant species.
汞重金属污染已成为全球范围内的一个重要环境问题。植物对汞离子的积累可能会破坏许多细胞功能，并阻止正常的生长和发育。为了评估汞重金属的毒性，我们进行了一项实验，重点研究了凤眼莲对汞诱导的氧化应激的反应。将凤眼莲幼苗暴露于不同浓度的汞中，以研究在水培系统下，汞离子积累水平、生长模式变化、抗氧化防御机制和 DNA 损伤。结果表明，在 50mg/L 处理下，植物生长速度显著抑制（52%）。在根、叶和叶柄组织中，汞离子水平的积累分别为 1.99mg/g 干重、1.74mg/g 干重和 1.39mg/g 干重。随着汞离子浓度的增加，叶绿素 a、b 和类胡萝卜素的含量呈下降趋势。叶片和根中的抗坏血酸过氧化物酶和丙二醛含量在 30mg/L 汞处理时呈上升趋势，在较高浓度时略有下降。重金属剂量与超氧化物歧化酶、过氧化氢酶和过氧化物酶抗氧化酶活性呈正相关，可作为监测凤眼莲污染的生物标志物。由于重金属胁迫，与对照相比，随机扩增多态性 DNA（RAPD）图谱中一些正常的 DNA 条带消失，并且扩增了一些额外的条带。RAPD 结果表明，汞重金属处理显著影响基因组模板的稳定性。我们得出结论，随机扩增多态性 DNA 分析所确定的 DNA 变化为检测植物物种中汞重金属污染的遗传毒性效应提供了一种有用的分子标记。
