中文摘要：

为了解Zn对长柔毛委陵菜耐受Cd的影响，通过营养液培养并采用差速离心技术和化学试剂逐步提取法研究了zn对长柔毛委陵菜（Potentilla griffithii var．velutina）体内Cd的亚细胞分布和化学形态的影响。结果表明，长柔毛委陵菜体内72％-95％的Cd分布在细胞壁和可溶组分中，这表明Cd主要分布在长柔毛委陵菜体内的细胞壁和可溶组分中，而在叶绿体、细胞核和线粒体中分布较少。同时，随Cd或Zn处理浓度的增加，细胞壁对Cd的固持作用增强。长柔毛委陵菜体内的Cd以不同化学形态存在：对照中73％～93％的Cd以水提取态和乙醇提取态存在，在其他处理中主要以氯化钠提取态、水提取态和乙醇提取态为主，三者占总量的86％～96％：其中在Zn／Cd复合处理中氯化钠提取态是含量最高的形态，所占比例为42％-78％；而醋酸提取态、盐酸提取态和残留态的含量在所有处理中分布都较低，只占总量的3％～14％。另外，随Cd或Zn处理浓度的增加，活性较强的水提取态和乙醇提取态的分配比例总和减少，而氯化钠提取态所占比例却增加，这表明Cd向活性较弱的化学形态转移。因此，细胞壁固持、可溶组分的液泡区隔化和向活性较弱的结合形态转移可能是长柔毛委陵菜耐Cd的主要机制。

英文摘要：

Using the differential centrifugation technique and sequential chemical extraction methods, effects of Zn on subcellular distribution and chemical forms of Cd under nutrient solution culture were studied to understand the influence of Zn on Cd tolerance in Zn hyperaccumulator Potentilla griffithii vat. velutina. The results showed that 72%-95% of total Cd were bound to cell wall and soluble fraction in the plant, and only a small quantity of Cd distributed in chloroplast, karyon and mitochondrion, which suggested that cell wall and soluble fraction in the plant were major storage sites for Cd. Moreover, cell wall binding Cd fraction increased with the increasing of Cd or Zn concentrations in the nutrient solution. As to Cd chemical forms, 73%-93% of total Cd existed as water- and ethanol-extractable forms in the plants under the control, and 86%-96% of total Cd existed as NaCl-, water- and ethanol-extractable Cd forms in other treatments. Whereas NaCl-extractable form, accounting for 42%-78% of total Cd, was dominant in Zn/Cd compound treatments. The percentage of NaCl-extractable Cd form increased but those of ethanol- and water-extractable Cd forms decreased with the increasing of Cd or Zn concentration, which indicated that Cd or Zn addition facilitated the transferring of Cd from relatively higher active chemical forms to less active ones. The results mentioned above indicate that cell wall binding, vacuolar compartmentalization in the soluble fraction and transferring to lower active chemical forms are main tolerance mechanisms for Cd in Potentilla griffithii var. velutina.