外源脯氨酸（Pro）对茶菱抗Cd2+胁迫能力的影响

以高等水生植物茶菱（Trapella sinensis Olive）为材料，研究了外施不同浓度的脯氨酸（Pro）对Cd²⁺毒害的缓解效应。结果表明，茶菱体内Pro含量在单一Cd²⁺毒害下明显增加，外施Pro后，显著降低；叶绿素和可溶性蛋白含量在单一Cd²⁺毒害下大幅下降，外施Pro后，失绿症状有所减轻；保护酶（SOD、CAT、POD）系统在单一Cd²⁺毒害下比例失调，平衡被打破，活性下降，外施Pro后，SOD、POD活性较对照升高，CAT持平，其比例维持在正常范围内；O^－₂产生速率在单一Cd²⁺毒害下大大加快，外施Pro后，其产生速率恢复正常水平；丙二醛（MDA）含量在单一Cd²⁺毒害下积累加剧，外施Pro后，积累程度有所降低。因此，外源Pro可以通过减轻叶绿素和可溶性蛋白的降解，促进蛋白合成，减缓MDA积累，降低O^－₂产生速率，增强保护酶活性来增强植物对重金属胁迫的抗性，增强植物对逆境的适应能力。本实验中Pro作用的最佳浓度范围为40~60 mg·L^-1。

Effects of Exogenous Pro on Resistance of Trapella sinensis Olive to Cd2+ Stress

The mitigation of toxic effect of Cd²⁺ on Trapella sinensis Olive by exogenous Pro was studied. The results showed that when treated with single 3 mg·L^-1 Cd²⁺ for 5 d,the Pro content increased,chlorophyll and soluble protein content dropped,the balance of antioxidase(SOD,POD,CAT) was broken and their activities decreased,MDA content,O^-₂ generation rate increased in T. sinensis Olive.When different conditions of Pro was added into the solution,Pro content dropped,the degradation of chlorophyll and soluble protein was alleviated,the activities of SOD and POD raised,the activity of CAT returned to normal level,the balance of antioxidase was rebuilt,the activity of antioxidase was enhanced, O^-₂ generation rate was dropped,and accumulation of MDA was reduced in comparison with single Cd²⁺ treatment. As a result, exogenous Pro can enhance the resistance of plants to heavy metal stress.The optimum dose of Pro to Cd²⁺ in T. sinensis Olive was ranged from 40~60 mg·L^-1.