秋茄叶对复合重金属的胁迫反应及其积累能力研究

Study on stress responses and bioaccumulation of multiple heavy metals by the leaves of Kandelia candel

为了探究重金属胁迫对红树植物秋茄Kandelia candel(L.Druce)生理指标的影响,通过砂培试验研究了秋茄在5个不同级别(T0、T1、T2、T3和T4)的复合重金属(镉、铅和汞)处理30d后某些生理特性的变化。结果表明,随着复合重金属胁迫浓度的增加,秋茄叶片吸收重金属量增加,而叶绿素含量明显减少。抗坏血酸(AsA)含量在T3达到最大值,但在T4减少到对照水平。当重金属处理浓度大于T1时,谷胱甘肽(GSH)含量显著增加。秋茄叶抗坏血酸过氧化物酶(APX)和谷胱甘肽还原酶(GR)活性变化趋势与AsA活性变化相似,呈先升后降趋势,在T3时酶活性都达到最大值。重金属处理对谷胱甘肽过氧化物酶(GPX)活性有显著诱导作用。综合实验结果,可初步判断秋茄叶能积累和忍受一定量的重金属;为了减少重金属胁迫造成的氧化伤害,秋茄叶片通过调节体内的抗氧化剂含量和抗氧化酶活性来抵御活性氧的攻击。

In order to probe into physiological effects of heavy metals on mangrove plant Kandelia candel,the changes of some physiological characteristics in the seedlings of Kandelia candel exposed to five various concentrations（T0,T1,T3,and T4） of multiple heavy metals（Cd,Pb,and Hg） for 30 days were studied using sand culture method.The results show that the concentration of Cd,Pb,and Hg in the leaves of Kandelia candel increased with increasing concentration of multiple heavy metals in the growth solution.The toxic effect and oxidative stress caused by heavy metals were evident by the reduction in photosynthetic pigments.Ascrobate（AsA） content increased up to T3 while down at T4.The content of glutathione（GSH） significantly increased when Kandelia candel was exposed to T2 and above.The activities of ascorbate peroxidase（APX） and glutathione reductase（GR） followed the same trends as AsA,which first increased up to T3 and then decreased.Glutathione peroxidase（GPX） activity showed significant induction at all heavy metal treatment.The results of the present study suggest that Kandelia candel was able to accumulate and tolerate heavy metals.Kandelia candel responded to heavy metals induced oxidative stress by modulating non-enzymatic antioxidants and enzymatic antioxidants.