硅提高水稻抗镉毒害机制的研究

Research on the Mechanism of Silica Improving the Resistance of Rice Seedlings to Cd

通过水培试验,主要从硅对镉的分布、镉的化学形态和过氧化物酶活性的影响以及与硅结合蛋白的关系等方面研究了硅减轻镉毒害的机制。结果表明,施硅能显著抑制镉向地上部的运输,使质外体运输途径的运输量减少了36%;加硅也降低了质外体中不同形态镉的含量,特别是结合态的镉;施硅显著降低了镉毒害所诱导的过氧化物酶活性,这说明加硅缓解了高浓度镉对水稻的毒害作用;免疫细胞化学定位显示硅结合蛋白主要分布在水稻根系表皮下的纤维层细胞及内皮层细胞附近,此部位是硅积累的主要部位,也是离子在质外体运输的关键入口,这从分子水平上解释了加硅可降低质外体途径的运输量。

Effect of silicon （Si） on alleviation of cadmium （Cd） toxicity to rice seedlings grown hydroponically under the toxic levels of Cd was investigated with special reference to the effect on Cd distribution, chemical forms of Cd, peroxidase activity and the relation with silicabinding protein. Si added significantly restricted the transport of Cd from roots to shoots and reduced the apoplastic transportation by 36%. Si decreased the concentration of Cd in three chemical forms in the intercellular washing fluid, especially DTPA-extractable Cd. We also found Si decreased the peroxidase activity induced by the toxicity of Cd, indicating that Si could reduce the toxicity of Cd to rice seedlings. Immunocytochemistry localization showed the silica-binding protein was mainly deposited in the vicinity of the fiber cell under the root epidermis and the endodermis, which were the main deposition positions of Si and also the critical entrance of ion in the apoplastic transport, interpreting why Si could reduce the apoplastic transportation from the molecular level.