镉在圆锥南芥(Arabis paniculata Franch.)中的亚细胞分布及其化学形态

Subcellular Distribution and Chemical Forms of Cd in Arabis paniculata Franch.

通过水培的方式,采用差速离心技术和化学试剂逐步提取法研究了Cd在圆锥南芥(Arabis paniculata Franch.)叶片和根中的亚细胞分布和化学形态。研究结果表明,在Cd处理浓度为1.0mg·L-1时,圆锥南芥叶片中的Cd主要贮藏在细胞壁和细胞核中,而根系中Cd的分布顺序为:细胞壁>核糖体>细胞核>叶绿体>线粒体;10.0mg·L-1Cd处理时,叶片中的Cd主要集中在细胞壁以及细胞核中,根系中核糖体含量最高,占全量的53.92%。这说明圆锥南芥叶片富集的Cd主要贮存在细胞壁以及细胞核中,而根系富集的Cd主要分布在核糖体与细胞壁中。化学形态结果表明Cd处理水平的变化对圆锥南芥Cd的化学形态有明显的影响。1.0mg·L-1Cd处理时,圆锥南芥叶片中以水提取态Cd为主,根系中乙醇提取态Cd的含量最高;当Cd提高到10.0mg·L-1时,叶片和根系中Cd均以NaCl提取态含量最高,说明随着Cd浓度的增加,Cd与蛋白质、果胶酸等形态结合是圆锥南芥减轻Cd毒害的主要机制。

Differential centrifugation and sequential chemical extraction were carried out to study the subcellular distribution and chemical form of Cd in the leaves and roots of Arabis paniculata Franch. The results showed that in A. paniculata, most of the Cd was bound to the cell wall, but Cd distribution in the leaves and roots was different. In the leaves, most of Cd stored in the cell wall and karyon, where as in the roots most of Cd stored in the ribosome and cell wall. The chemical forms of Cd changed with increasing Cd concentration. When Cd concentration in solution was 1 mg·L^-1, water-extractable and ethanol-extractable Cd predominated in the shoots and roots, respectively. When Cd supply level was up to 10mg·L^-1, the NaCl-extractable Cd was the highest form both in leaves and roots, which indicated that the combination of Cd with protein and pectate may play a role in Cd detoxification of A. paniculata under high Cd stress.