摘要
本研究以水培的烤烟给予不同浓度的Cd、Pb及其复合物处理10d后的烟叶为材料，分析了烟叶过氧化氢酶、硝酸还原酶的活性变化，测试了烟叶可溶性糖含量的变化情况，通过透射电子显微镜观察到了Cd和Pb对烟叶叶肉细胞亚显微结构的改变，特别是对叶绿体、线粒体和细胞核结构的损伤情况进行了详细观察。并探讨其毒害机理。研究结果表明：1）烟叶过氧化氢酶的活性剧烈地被Cd抑制；而随着Pb浓度的增加，其活性则表现为先增加后减弱的变化。2）Cd对硝酸还原酶活性的影响表现为光刺激增强，当Cd浓度超过50mg·L-1后，Cd剧烈地抑制其活性，当Cd浓度为200mg·L-1时，其活性几乎为零；Pb抑制烟叶硝酸还原酶的活性，仅在1000mg·L－1时出现一个低于正常活性的抗性峰。3）烟叶可溶性糖含量对Cd、Pb及其复合污染非常敏感，在较低浓度的污染处理时，其含量就明显下降，烟叶可溶性糖含量的变化可作为监测Cd、Pb污染的指标。4）Cd对烟叶叶肉细胞亚显微结构具有较强的损伤诱变作用，对细胞核、叶绿体和线粒体造成不可逆转的伤害，破坏了细胞正常生理活动所需的结构基础。电镜观察表明Cd严重地破坏细胞的膜结构。这可能是由于Cd离子与蛋白质结合而使蛋白质变性，从而使得以蛋白质为重要组成成份之一的膜的结构改变，功能丧失?
Catalase and NR activity and soluble sugar content was analyzed in leaves of tobacco plants grown for 10 days in a nutrient solution containing heavy metal pollutants (Cd2+ , Pb2+ and Cd2+＋Pb2+ ). Cadmium and lead induced changes in the ultra-structure of tobacco leaf cells, particularly in the structure of the chloroplast, mitochondrion and nucleus, were observed using electron microscopy. This showed that: 1) The activity of catalase was heavily inhibited by Cd, and first stimulated then inhibited with increasing concentrations of Pb; 2) The activity of NR was first stimulated and then inhibited with increasing concentration of Cd, but was inhibited by lead, with a small resistant peak at 1000mg· L-1; 3) Soluble sugar content was reduced by Cd, Pb and Cd ＋ Pb; 4) Cadmium destroyed the cell membrane system. It is suggested that this may result from cadmium combining with, and denaturing, proteins. This would lead to change in structure and loss of function in the membrane and to disorder in the protoplasm;5) Massive lead deposits were observed in the outer cell membrane, and lead deposits were found in the cytoplasm and chloroplast. The cell membrane was found to be a major barrier to lead migrating into the protoplasm. Lead also had a strong effect on the ultra-structure of chloroplasts, mltochondrla and nuclel.
出处
《植物生态学报》
CAS
CSCD
北大核心
2000年第2期238-242,共5页
Chinese Journal of Plant Ecology
基金
云南农业大学青年教师研究基金!95-03
关键词
烟叶
生理变化
亚显微结构
铅
镉
污染
Tobacco, Physiological features, Ultra-structure, Cd^(2+), Pb^(2+), Pollution
