Cd、Zn及其交互作用对互花米草中重金属的积累、亚细胞分布及化学形态的影响

Effects of Cd,Zn and Their interactions on Accumulation,Subcellular distribution and Chemical Forms of Heavy Metals in Spartina alterniflora

通过盆栽试验,研究了Cd、Zn及其交互作用下互花米草中Cd、Zn的含量及积累量,并分析了Cd、Zn在互花米草中的亚细胞分布及化学形态。结果表明:Cd-Zn处理组互花米草地上部及根部Cd含量显著高于Cd处理组;Cd-Zn处理组根部Zn含量显著低于Zn处理组,但地上部差异不显著,说明Zn促进Cd的吸收,Cd抑制Zn的吸收。Cd-Zn处理组互花米草地上部Cd积累量显著高于Cd处理组,但是根部Cd积累量却显著低于Cd处理组;Zn处理组地上部及根部Zn积累量均显著高于对照组及Cd-Zn处理组。Cd单因素胁迫下,Cd主要分布在细胞壁,Cd-Zn交互作用下,Cd在胞液中的分配比例高于其他细胞组分;Zn单因素及Cd-Zn交互作用下,Zn在胞液中的分配比例均较高,总的分配比例呈现以下趋势:胞液>细胞壁>细胞器,说明Zn的添加影响了Cd的亚细胞分布,Cd的出现对Zn在互花米草细胞中的分布影响不明显。Cd和Zn在互花米草叶中主要以氯化钠提取态存在,表明互花米草中Cd和Zn多以果胶酸盐结合态或蛋白质结合态存在。

A pot culture experiment was carried out to study the effects of cadmium （Cd） and zinc （Zu） singly and in combination on the accumulation, subcellular distribution of Cd and Zn in Spartina aherniflora, and the chemical forms of Cd and Zn in leaves of S. aherniflora were also determined. The results showed that the content of Cd in shoots and roots orS. alterniflora under Cd-Zn treatment was significantly higher than Cd treatment. Cd content in roots was Significantly lower under Cd-Zn treatment than Zn treatment, while there was no significant difference for shoots. These results showed that Zn accelerated the uptake of Cd, while Cd restained the uptake of Zn. Cd accumulation was significantly higher in shoots under Cd-Zn treatment than Cd treatment, while the trend was opposite in roots. Zn accumulation was greatly higher in shoots and roots under Zn treatment than con- trol and Cd-Zn treatment. Cd was mainly accumulated in cell wall under Cd treatment, while it was mainly accu- mulated in cytoplasmic supernatant under Cd-Zn treatment. Zn was mainly accumulated in cytoplasmic superna- tant under Zn and Cd-Zn treatments, and the subcellular distribution of Zn presented the following order： cyto- plasmic supematant 〉 cell wall 〉 cell organelie. These results indicated an interaction between Cd and Zn at sub- cellular level. Most of the Cd and Zn in leaves of S. aherniflora was extracted by 1 mol · L^- 1 NaCl, indicating most Cd and Zn was integrated with pectates and protein.