根细胞壁及其组分差异对植物吸附、转运Zn的影响

采用水培实验,研究了不同植物根细胞壁组分差异对Zn吸收、转运的影响及其机制.结果表明,在50mg/LZn处理下,不同植物对Zn的吸收、转运系数顺序为:小白菜≈芥菜≈生菜>青椒>西红柿>水稻,而在20mg/L Zn处理下,生菜茎叶中Zn的转运系数则大于芥菜,这可能与低浓度条件下Zn对生菜产生的低剂量刺激效应有关;利用植物活体根细胞解吸法对不同植物活体根系细胞壁中的Zn含量测定结果表明,不同植物的根细胞壁在去除了果胶成分后,根细胞壁中Zn的含量显著增加,其中水稻根细胞壁增加最大,达到53.7%,增加最小的是青椒(21.1%),而去除半纤维素后则显著降低了不同植物根细胞壁中Zn的含量,尤其是水稻根细胞壁最明显;吸附动力学实验表明,不同处理后的细胞壁对Zn的吸附是个快速反应过程,在吸附30min内所有处理均达到最大吸附量的91%以上,去除果胶显著增加不同细胞壁对Zn的吸附量,而进一步去除半纤维素后,不同细胞壁对Zn的最大吸附量显著下降.以上结果表明,半纤维素含量的增加明显提高了不同植物根束缚Zn的能力而降低向地上部的运输.

Difference in cell wall components of roots and its effect on the transfer factor of Zn by plant species

A hydroponic culture experiment was conducted to investigate the uptake and transfer factor(TF) of zinc(Zn) by different plant species,the translocation and the redistribution of Zn in the cell wall and its’ components were also studied.The results showed that the Zn uptake and its translocation differed significantly between six cultivars,the largest shoot Zn concentrations were found in Chinese cabbage and lettuce,while rice had the largest Zn concentration in root.With the addition of 50mg/L Zn in solution,the shoot to root transfer factors of Zn by plant species followed: Chinese cabbage ≈ leaf mustard ≈ lettuce>sweet green pepper > tomato > rice,however,the TF of lettuce exceeded the leaf mustard under the lower addition concentration(20mg/LZn),it’s probably related with the hormesis of Zn phyto-toxicity to lettuce.The Zn immobilization by cell wall was an important mechanism for Zn detoxification.By the in-situ desorption technique,the Zn accumulation in cell walls and their components were measured.The result showed that the Zn contents of cell walls increased significantly after removing pectin among plant species,the largest increment of 53.7% was found with rice while the least(21.1%) with sweet green pepper.The result of adsorption kinetics of Zn on the root cell walls indicated the adsorption of Zn by raw cell walls and treated cell walls was a fast reaction,more than 91% of total Zn was adsorbed by the adsorbents within 30min,the adsorption maximum of Zn by cell walls increased significantly after removing pectin among plant species,on the contrary,the adsorption maximum of Zn by cell walls decreased remarkably after removing pectin and hemicellulose,especially with the cell walls of rice.The results indicated that the hemicellulose components in cell walls played an important role in bonding Zn and thereafter reducing the translocation of Zn in xylem in plants.