谷胱甘肽在东南景天Zn/Cd超积累过程中的作用

Role of reduced glutathione in Zn and Cd hyperaccumulation in Sedum alfredii H.

超积累生态型东南景天被处理在含1000μmol·L-1Zn(NO3)2或200μmol·L-1CdCl2的营养液中25 d,每5 d测定植株地上和地下部Zn/Cd含量以及地上部总硫、谷胱甘肽(GSH)含量的变化,分析硫离子浓度对重金属积累能力的影响.结果表明:处理的前15 d,地上部Zn/Cd的积累量呈线形增加,后10 d积累速度下降;总硫和GSH的含量在前15 d迅速增加,后10 d逐渐下降;根中Zn含量变化与地上部GSH、总硫变化趋势相似,而Cd含量在第5 d时最高,以后逐渐下降.以上结果提示:含硫有机物不是东南景天Zn/Cd超积累的主要配体,GSH主要是解除体内游离态Zn/Cd的毒性;增加硫元素的供应对提高Zn/Cd的积累有一定作用.

Hyperaccumulating ecotype of Sedum alfredii H. was treated with 1000μmol· L^-1 Zn（NO3 ）2 or 200 μmol·L^-1 CdCl2 for 25 days. Zn and Cd concentrations in plants, total sulphur （S） and reduced glutathione （GSH） in shoots, were detected every 5 days after treatment. Effects of S on Zn/Cd accumulation in Sedum alfredii H. were also investigated. The results indicate that Zn/Cd concentration in shoots of Sedum alfredii H. increased linearly within 15 days and after that increasing rate was declined considerably. Concentrations of total S and GSH in shoots were also increased within 15 days, and then decreased. Zn concentration in roots was found to he positively correlated with total S or GSH concentration in shoots, however, there is no such relationship with accumulation of Cd in the presence of S and GSH. These results suggest that SH-containing ligands is not the main chelator of Zn/ Cd in the hyperaccumulating ecotype of Sedum alfredii H. GSH probably plays an important role in the detoxification of dissociated zinc/cadmium, while increasing S supplying level could increase zinc and cadmium accumulation of Sedum alfredii H. significantly.