Zlobin Ilya E, Kartashov Alexander V, Shpakovski George V
Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Botanicheskaya ul. 35, 127276 Moscow, Russia.
Timiryazev Institute of Plant Physiology, Russian Academy of Sciences, Botanicheskaya ul. 35, 127276 Moscow, Russia.
Plant Physiol Biochem. 2017 Sep;118:333-341. doi: 10.1016/j.plaphy.2017.06.029. Epub 2017 Jun 28.
We investigated the specific features of copper and zinc excess action on the roots of canola (Brassica napus L.) plants. Copper rapidly accumulated in canola root cells and reached saturation during several hours of treatment, whereas the root zinc content increased relatively slowly. Excessive copper and zinc entry inside the cell resulted in significant cell damage, as evidenced by alterations in plasmalemma permeability and decreases in cellular enzymatic activity. Zinc excess specifically damaged root hair cells, which correlated with a pronounced elevation of their labile zinc level. In vitro, we showed that reduced glutathione (GSH) readily reacted with copper ions to form complexes with blocked sulfhydryl groups. In contrast, zinc ions were ineffective as glutathione blockers, and glutathione molecules did not lose their specific chemical activity in the presence of Zn ions. The effect of copper and zinc excess on the glutathione pool in canola root cells was analysed by a combination of biochemical determination of total and oxidized glutathione contents and fluorescent staining of free reduced glutathione with monochlorobimane dye. Excess copper led to dose-dependent diminution of free reduced glutathione contents in the root cells, which could not be explained by the loss of total cellular glutathione or its oxidation. In contrast, we observed little effect of much higher intracellular zinc concentrations on the free reduced glutathione content. We concluded that GSH plays an important role in copper excess, but not zinc excess chelation, in canola root cells.
我们研究了铜和锌过量作用于油菜（Brassica napus L.）植株根系的具体特征。铜在油菜根细胞中迅速积累，并在处理数小时内达到饱和，而根中锌含量增加相对缓慢。细胞内过量的铜和锌导致了显著的细胞损伤，这可通过质膜通透性的改变和细胞酶活性的降低得以证明。锌过量特异性地损伤了根毛细胞，这与根毛细胞中不稳定锌水平的显著升高相关。在体外，我们发现还原型谷胱甘肽（GSH）很容易与铜离子反应形成具有封闭巯基的复合物。相比之下，锌离子作为谷胱甘肽阻断剂无效，并且在锌离子存在的情况下谷胱甘肽分子不会丧失其特定的化学活性。通过结合对总谷胱甘肽和氧化型谷胱甘肽含量的生化测定以及用单氯联苯胺染料对游离还原型谷胱甘肽进行荧光染色，分析了铜和锌过量对油菜根细胞中谷胱甘肽库的影响。过量的铜导致根细胞中游离还原型谷胱甘肽含量呈剂量依赖性减少，这无法用细胞总谷胱甘肽的损失或其氧化来解释。相比之下，我们观察到细胞内锌浓度高得多时对游离还原型谷胱甘肽含量的影响很小。我们得出结论，在油菜根细胞中，GSH在过量铜螯合中起重要作用，但在过量锌螯合中不起作用。
