Wang Feijuan, Zeng Bin, Sun Zongxiu, Zhu Cheng
State Key Laboratory of Plant Physiology & Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, China.
Arch Environ Contam Toxicol. 2009 May;56(4):723-31. doi: 10.1007/s00244-008-9226-2. Epub 2008 Sep 12.
There has been little agreement regarding the mechanism by which proline reduces heavy metal stress. The present work examines the relationship between Hg(2+)-induced oxidative stress and proline accumulation in rice and explores the possible mechanisms through which proline protects against Hg(2+) stress. The effect of proline on alleviation of Hg(2+) toxicity was studied by spectrophotography and enzymatic methods. Hg(2+) induced oxidative stress in rice by increasing lipid peroxidation. Pretreatment of the rice with 2 mM proline for 12 h profoundly alleviated Hg(2+)-induced lipid peroxidation and minimized H(2)O(2) accumulation. Proline pretreatment significantly reduced (p < 0.01) the Hg(2+) content in rice leaves. A comparison of the effects of proline pretreatment on H(2)O(2) accumulation by Hg(2+) and aminotrazole suggested that proline protected cells from Hg(2+)-induced oxidative stress by scavenging reactive oxygen species. The present work demonstrates a protective effect of proline on Hg(2+) toxicity through detoxifying reactive oxygen species, rather than chelating metal ions or maintaining the water balance under Hg(2+) stress.
关于脯氨酸减轻重金属胁迫的机制，目前尚未达成共识。本研究考察了汞离子（Hg(2+)）诱导的氧化应激与水稻中脯氨酸积累之间的关系，并探究了脯氨酸抵御Hg(2+)胁迫的可能机制。采用分光光度法和酶法研究了脯氨酸对减轻Hg(2+)毒性的作用。Hg(2+)通过增加脂质过氧化作用诱导水稻产生氧化应激。用2 mM脯氨酸对水稻进行12小时预处理，可显著减轻Hg(2+)诱导的脂质过氧化作用，并使过氧化氢（H(2)O(2)）积累量降至最低。脯氨酸预处理显著降低了（p < 0.01）水稻叶片中的Hg(2+)含量。比较脯氨酸预处理对Hg(2+)和氨基三唑诱导的H(2)O(2)积累的影响表明，脯氨酸通过清除活性氧保护细胞免受Hg(2+)诱导的氧化应激。本研究表明，脯氨酸通过清除活性氧对Hg(2+)毒性具有保护作用，而不是通过螯合金属离子或在Hg(2+)胁迫下维持水平衡。
