拟南芥对镉胁迫的生理响应

Physiological Responses of Arabidopsis Thaliana to Cadmium Stress

研究拟南芥对不同Cd2+浓度处理(0、20、40、60、80μmol/L)的生理响应,探讨Cd2+对植物的毒性效应及植物的耐性机理.结果发现,各浓度Cd2+导致拟南芥过氧化氢酶和超氧化物歧化酶活性显著降低(P<0.05)、植物根部细胞DNA出现明显的损伤,拟南芥生物量及根长也显著降低(P<0.05),表明Cd2+对拟南芥体内的生物大分子产生了严重的胁迫效应.叶片光合色素含量随Cd2+浓度的升高而逐渐下降,在60、80μmol/L时处理效应达到显著水平(P<0.05),表明高Cd2+抑制植物的光合作用.拟南芥体内丙二醛及可溶性蛋白含量随Cd2+浓度的增加明显上升,在60μmol/L时处理效应显著(P<0.05),表明Cd2+胁迫导致其膜脂过氧化效应.在全部Cd2+处理下,拟南芥体内谷胱甘肽和植物螯合肽的含量均显著上升(P<0.01);类黄酮、花色素苷等酚类物质也随Cd2+浓度的增加而上升,并在高Cd2+浓度(60、80μmol/L)下处理效应达到显著水平(P<0.05),表明拟南芥通过积累具有活性氧抗性的次级代谢产物提高其对Cd2+的耐受性.本研究结果为深入研究Cd2+对植物毒害的分子机制以及植物对Cd2+耐性的分子机制提供依据.

To illustrate the toxic effects of Cd2＋ on plants and their tolerance mechanisms, the physiological responses of Arabidopsis thaliana L. under different Cd2＋ treatments （0, 20, 40, 60 and 80 μM） were investigated. The results showed that compared to control plants, there were significantly lower biomass and root length of plants in Cd2＋ treatments （P〈0.05）. The application of Cd2＋ induced obvious DNA injury in plant roots, and caused significant inhibitory effects on SOD and POD activities （P〈0.05）. 20 μM or higher Cd2＋ concentrations can lead to high oxidative stresses on the biomacromolecules of plant. The photosynthetic pigments contents of A. thaliana were gradually decreased following increased Cd2＋, and statistically significant effects were observed under 60 and 80 μM Cd2＋ treatments （P〈0.05）, indicating that the high Cd2＋ treatments inhibited photosynthesis of plants. The soluble protein and MDA contents increased obviously following increased Cd2＋ concentrations, and significantly higher contents of them were observed in 60 and 80 μM Cd2＋ treatments than that in the control （P〈0.05）, indicating that membrane lipid peroxidation were induced by high Cd2＋ application. The glutathione and phytochelatin contents of plant showed significant increases following increased Cd2＋ concentrations （P〈0.05）. There were also higher contents of flavonoid and anthocyanin in the plants under Cd2＋ treatments, indicating that accumulation of secondary metabolites with antioxidant activities was one of the strategies in A. thaliana to improve their Cd2＋ tolerance. The present study could provide experimental data on the exploration of the molecular mechanisms of toxic effects of Cd2＋ on plants and their tolerance strategies.