镉胁迫下钙对镉在玉米细胞中分布及对叶绿体结构与酶活性的影响

EFECTS OF CALCIUM SUPPLY ON SUBCELLULAR DISTRIBUTION OF CADMIUM, CHLOROPLAST ULTRASTRUCTURE,RuBPC AND PEPC ACTIVITY IN MAIZE UNDER CADMIUM STRESS

采用溶液培养试验、亚细胞组分分级分离技术、透射电子显微镜观察及生化分析等方法研究钙对镉胁迫下玉米根、叶组织镉的亚细胞分布、叶绿体超微结构及叶片RuBP 羧化酶和PEP 羧化酶活性的影响。结果表明,与缺钙加镉处理比较,镉毒害下添加钙,玉米根、叶细胞器和细胞质Cd 组分均显著下降,相应Ca 组分则显著增加,而细胞壁Cd 、Ca 含量各处理间均十分接近;镉毒害下添加钙,维管束鞘细胞基质片层及叶肉细胞基粒和基粒片层排列较好,维管束鞘细胞嗜锇粒大为减少,叶片RuBP和PEP羧化酶活性显著增加。说明Ca 对于Cd 胁迫下玉米叶片正常结构与功能的保持具有十分重要的意义。

Solution culture, subcellular fractionating procedure, electron microscopy examination and biochemical analysis were used to study the effects of calcium supply on subcellular distribution of cadmium, chloroplast ultrastructure and RuBPC and PEPC activity in maize seedlings under cadmium stress. Compared to no calcium supply under cadmium stress, calcium supply could significantly lower Cd content and increase Ca content in both organelles and cytoplastic fraction in roots and leaves of maize, while no such sighs were observed with cell wall fraction. In calcium supply treatment under cadmium stress, stroma lamellae in chloroplast of mestome sheath and grana and grana lamellae in mesophyll were better arranged, and much less osmiophilics appeared in chloroplast of mestome sheath, compared to that of no calcium supply treatment. It was also found that RuBPC and PEPC activity in leaves of maize under cadmium stress significantly increased by supplying Ca. It was concluded that calcium play a very important role in maintaning normal structure and function for plants under cadmium stress.