摘要
紫羊茅(Festuca rubra L.)有对重金属敏感(“S59”)和忍耐(“Merlin”)两个品种。以0～2.5mmol/LCd^(2+)的营养液分别培养“S59”和“Merlin”幼苗,随着Cd^(2+)浓度增加和处理时间延长,幼苗生长量相应下降。0.25mml/L Cd^(2+)对“S59”的生长抑制与0.5mmol/L Cd^(2+)对“Merlin”的抑制相似,表明“Merlin”比“S59”更能耐受Cd^(2+)的毒害。在Cd^(2+)抑制生长的同时,幼苗的MDA(丙二醛,膜脂过氧化产物)和POD(过氧化物酶)活性急剧上升,CAT(过氧化氢酶)和SOD活性降低,蛋白质含量明显下降。MDA大幅度上升是Cd^(2+)培养幼苗突出的生理变化之一,2.5mmol/L Cd^(2+)培养幼苗6d,“Merlin”的MDA为对照的209％,而“S59”为对照的243％。MDA的积累与培养幼苗的Cd^(2+)浓度成密切正相关,与幼苗的生长量呈负相关。当SOD活性平稳或略为上升时,MDA稳定;SOD活性开始下降,MDA便急剧上升。很可能自由基和MDA在Cd^(2+)毒害植物中充当了重要的角色。
Two cultivars of Festuca rubra L. , namely metal tolerant 'Merlin' and metal sensitive 'S59',were treated with culture media containing Cd2+ at various concentrations ranging from 0 to 2.5 mmol/L. The biomass of the grass seedlings of both cultivars was significantly dropped in connection to increase in metal concentration and treatmental time. The degree of inhibition by 0.5 mmol/L Cd2+ in 'Merlin' was quite similar to that caused by 0.25 mmol/L Cd2+ in 'S59',indicating that 'Merlin' was relatively resistant to metal stress. Accompanying with the inhibition of growth by Cd2+ ,malonyl dialdehyde (MDA) content and peroxidase (POD) activity measured in the seedlings increased drastically, while the activities of catalase (CAT) and superoxide dismutase (SOD) decreased with significant drop in total protein content.The remarkable enhancement of MDA in the grass seedlings appeared to be an obvious physiological response due to Cd2+ treatment. When plants treated with 2.5 mmol/L Cd2+ for 6 days,MDA increased by 109% and 143% in 'Merlin' and 'S59' , respectively. There was a close positive correlation between MDA content and Cd2 + concentration , and a negative correlation between MDA and plant growth. As slight decrease in SOD activity was found accompanied by a drastic elevation of MDA content. This observation may imply that free radical and MDA may play an important role in the Cd2+ led toxicity in plants.
基金
国家自然科学基金
关键词
植物
环境污染
重金属污染
镉毒害
自由基
Pollution by metals, Cadmium toxicity, free radicals, SOD, malonyl dialdehyde
