Shi Heping, Wang Yunling, Tsang PoKeung Eric, Chan LeeWah Andrew
Guangdong Key Laboratory of Biotechnology for Plant Development, College of Life Science, South China Normal University, Guangzhou 510631, Guangdong, China.
Sheng Wu Gong Cheng Xue Bao. 2012 Jun;28(6):747-62.
In order to study the physiological mechanism of exogenous calcium on the toxicity of heavy metal cadmium (Cd) to Wedelia trilobata hairy roots, the effects of Cd alone, and in combination with different concentrations of Ca on growth, contents of soluble protein and malondialdehyde (MDA), activities of superoxide dismutase (SOD) and peroxidase (POD), Cd2+ absorption in W. trilobata hairy roots were investigated. Cd concentrations lower than 50 micromol/L enhanced the growth of hairy roots, while concentrations higher than 100 micromol/L inhibited growth, making the branched roots short and small, and also turning the root tips brown, even black. In comparison with the control (0 micromol/L Cd), the soluble protein content in hairy roots was found to increase when cultured with 10-50 micromol/L Cd, and decrease when exposed to a cadmium concentration higher than 100 micromol/L Cd. In addition, the activities of POD and SOD activity and MDA content were significantly higher than the control. Compared to the control (hairy roots cultured without 10-30 mmol/L Ca), 100 micromol/L Cd or 300 micromol/L Cd in combination with 10-30 mmol/L Ca resulted in increased growth, causing the main root and secondary roots thicker and also an increase in soluble protein content. On the contrary, MDA content and POD and SOD activities decreased. Quantitative analysis by Atomic Absorption Spectrophotometry showed that W. trilobata hairy roots can absorb and adsorb heavy metal Cd in the ionic form of Cd2+. The maximum content of Cd2+ absorbed by the hairy roots was obtained with a concentration 100 micromol/L Cd2+ while that of Cd2+ adsorbed by hairy roots was achieved with a concentration of 300 micromol/L Cd2+. The exogenous addition of 10-30 mmol/L Ca2+ was found to reduce the absorption, adsorption of Cd2+ and the toxicity of Cd significantly. This reduction in toxicity was caused by the reduction in the absorption of Cd and decreasing the lipid peroxidation through regulating the activities of antioxidant enzymes SOD and POD in the hairy roots.
为研究外源钙对重金属镉（Cd）对三裂叶蟛蜞菊毛状根毒性的生理机制，研究了单独的Cd以及与不同浓度Ca组合对三裂叶蟛蜞菊毛状根生长、可溶性蛋白和丙二醛（MDA）含量、超氧化物歧化酶（SOD）和过氧化物酶（POD）活性、Cd2+吸收的影响。低于50微摩尔/升的Cd浓度促进毛状根生长，而高于100微摩尔/升的浓度抑制生长，使分支根短而小，根尖变为褐色甚至黑色。与对照（0微摩尔/升Cd）相比，用10 - 50微摩尔/升Cd培养时，毛状根中可溶性蛋白含量增加，而暴露于高于100微摩尔/升Cd的镉浓度时则降低。此外，POD和SOD活性以及MDA含量显著高于对照。与对照（不添加10 - 30毫摩尔/升Ca培养的毛状根）相比，100微摩尔/升Cd或300微摩尔/升Cd与10 - 30毫摩尔/升Ca组合导致生长增加，主根和侧根变粗，可溶性蛋白含量也增加。相反，MDA含量以及POD和SOD活性降低。原子吸收分光光度法定量分析表明，三裂叶蟛蜞菊毛状根能够以Cd2+离子形式吸收和吸附重金属Cd。毛状根吸收Cd2+的最大含量在Cd2+浓度为100微摩尔/升时获得，而毛状根吸附Cd2+的最大含量在Cd浓度为300微摩尔/升时实现。发现外源添加10 - 30毫摩尔/升Ca2+可显著降低Cd2+的吸收、吸附以及Cd的毒性。毒性降低是由于Cd吸收减少以及通过调节毛状根中抗氧化酶SOD和POD的活性降低脂质过氧化作用所致。
