甜菜幼苗抗氧化系统对锰胁迫的生物学响应

Biological Response of Antioxidant system of Sugar beet seedling to Manganese stress

采用砂培方法，对锰胁迫下甜菜幼苗的膜脂过氧化作用及保护系统的反应进行了研究。结果表明，随着锰浓度和处理时间的增加，甜菜幼苗叶片O2^-·生成速率和H2O2含量呈上升趋势。高剂量（0．8mmol·L^-1）长时间（20d）锰处理，O2^-及H2O2含量下降，具有明显的时间和剂量累加效应。锰胁迫增加了膜脂过氧化产物MDA的含量，高锰（0．8mmol·L^-1）处理（15d），MDA含量达峰值，显示叶肉细胞氧化速率加快，自我修复能力减弱。锰处理对甜菜叶片SOD活性显现明显的激活效应，随锰浓度加大和处理时间延长，根部SOD活性呈抑制效应。叶和根APX活性均呈先升后降的趋势；CAT活性为锰胁迫初期激活、中后期迅速下降的抑制作用。随锰处理剂量的增加和时间延长，叶片的APX和CAT降幅均大于根部。中度（0．5mmol·L^-1）锰污染，甜菜叶片AsA和GSH含量大幅增加，说明此时非酶抗氧化剂AsA、GSH对H2O2的清除能力提高，发挥了重要的抗氧化作用。

Pot experiment was conducted to explore the effect of membrane lipid per - oxidation and the response of protection system of sugar beet seedling under the condition of manganese stress. The results show that as the anganese concentration and the processing time increase, O2^- production rate and H2O2 content of sugar beet seedling leaf shows the trend of increasing. 02 - and H2O2 content decrease when treated with high dose （0.8 mmol. L - 1 ） manganese for a long time （20d） which shows significant additive effect of time and dose. Manganese stress increases the content of membrane lipid per - oxidation product MDA, its content reaches the peak when treated with high dose（0.8 mmol-L-I） manganese for 15d which shows Oxidation rate accelerating of leaf cells and decreased ability to repair itself. Manganese treatment shows significant activation effects to SOD activity in leaves of Sugar beet seedling, with increasing manganese concentration and treatment time, SOD activity in root was inhibited. APX activity in leaves and roots showed a trend first increased and then decreased;in the early time of Manganese treatment, CAT activity was actived ,while in the late time rapidly declined. With the increas- ing Manganese concentration and treatment time, Drop of APX and CAT in leaf were higher than root. Moderate （ 0.5 mmol. L-1 ） manganese pollution made AsA and GSH content significantly increase which showed non - en- zymatic antioxidants AsA,GSH had a higher ability to remove H2O2 and played an important role in the antioxi- dant.