镉积累不同类型的小麦细胞镉的亚细胞和分子分布

Subcelluar and Molecular Distribution of Cadmium in Two Wheat Genotypes Differing in Shoot/Root Cd Partitioning

采用溶液培养试验结合亚细胞组分分级分离和凝胶过滤等技术 ,研究小麦根系和叶片细胞镉的亚细胞和分子分布。低镉和高镉品种分别采用烟 86 10 3和莱州 95 3。在高镉与低镉营养液中 ,根细胞壁中镉含量两个品种间差异不大 ,但烟 86 10 3根系细胞质中镉含量较低 ;叶片细胞壁、细胞质和细胞器的镉含量均表现为烟 86 10 3小于莱州 95 3。两小麦品种叶片细胞中镉大部分与高分子量化合物配合 ,而根细胞中镉大部分与重金属螯合肽 (PCs)配合。根系镉与PCs配合的组分 (PCs Cd)含量烟 86 10 3远小于莱州 95 3,烟 86 10 3根系细胞质低的镉含量以及低的PCs Cd形成量 ,降低了根系镉的移动及其由木质部向地上部转运的可能性。

In an effort to understand the biological process of Cd bioaccumulation, a solution culture experiment combined with subcelluar fractionation and gel filtration were carried out to investigate subcellular and molecular distribution of Cd in roots and leaves of wheat. Two wheat cultivars, Laizhou953, a high Cd accumulating cultivar, and Yan86103, a low Cd accumulating cultivar, were compared. Cd content in cell wall of roots in Yan86103 was equivalent to that of Laizhou953 under different solution Cd supply, but that in cytoplasm of roots in Yan86103 was significantly lower than that of Laizhou953. Cd contents in all of the cell wall, cytoplasm and cell organelles of leaves were greatly lower in Yan 86103 than those of in Laizhou953. For both two genotypes, the majority of soluble Cd in leaves was bounded to high molecular weight components, while that in roots was mainly associated with phytochelatins components (PCs). Concentration of Cd PCs in roots was found to be greatly lower in Yan86103 than that of in Laizhou953, which possibly resulted in a lower Cd mobility in roots and less Cd traslocation from roots to shoot via xylem.