Zhang Haiyan, Jiang Yingnan, He Zhenyan, Ma Mi
Key Laboratory of Photosynthesis and Molecular Environmental Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, Xiangshan 100093, PR China.
J Plant Physiol. 2005 Sep;162(9):977-84. doi: 10.1016/j.jplph.2004.10.001.
To investigate the temporal sequence of physiological reactions of garlic (Allium sativum) to cadmium (Cd) treatment, seedlings developed from cloves were grown in increasing concentrations of CdCl2, ranging from 1-10 mM, for up to 8 days in sand. Analysis of Cd uptake indicated that most Cd accumulated in roots, but some was also translocated and accumulated in leaves at longer exposure time (after 12h) and higher concentrations (5 and 10mM) of CdCl2. Changes in activities of antioxidative enzymes, including superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT), were characterized in leaves of garlic seedlings. Cd (5 and 10 mM) initially inhibited the activities of SOD and CAT but thereafter recovered or even increased compared with control plants. POD activities at 5 and 10 mM of Cd increased more than 3-4 times over control plants within 12 h and then dropped, but were still higher than controls at the end of the experiment. Otherwise lipid peroxidation enhanced with the increasing of incubation time and concentrations of external Cd. Leaves exposed to 1 mM CdCl2 showed a less pronounced response and only a small reduction in shoot growth. These results suggested that in leaves of garlic seedlings challenged by CdCl2 at higher concentrations, induction of these various enzymes is part of a general defense strategy to cope with overproduction of reactive oxygen. The possible mechanism of antioxidative enzymes changing before Cd accumulation in leaves of garlic seedlings is discussed.
为研究大蒜（Allium sativum）对镉（Cd）处理的生理反应的时间顺序，将蒜瓣培育出的幼苗在浓度逐渐增加（1-10 mM）的CdCl2中于沙子里培养长达8天。对镉吸收的分析表明，大部分镉积累在根部，但在较长暴露时间（12小时后）以及较高浓度（5和10 mM）的CdCl2处理下，部分镉也会转运并积累在叶片中。对大蒜幼苗叶片中抗氧化酶活性的变化进行了表征，这些抗氧化酶包括超氧化物歧化酶（SOD）、过氧化物酶（POD）和过氧化氢酶（CAT）。镉（5和10 mM）最初抑制了SOD和CAT的活性，但与对照植株相比，随后有所恢复甚至升高。5和10 mM镉处理下的POD活性在12小时内比对照植株增加了3-4倍以上，然后下降，但在实验结束时仍高于对照。此外，脂质过氧化随着孵育时间和外部镉浓度的增加而增强。暴露于1 mM CdCl2的叶片反应不太明显，地上部生长仅略有减少。这些结果表明，在受到较高浓度CdCl2挑战的大蒜幼苗叶片中，这些各种酶的诱导是应对活性氧过量产生的一般防御策略的一部分。本文还讨论了大蒜幼苗叶片中镉积累之前抗氧化酶变化的可能机制。
