增强UV-B辐射对麻花艽叶片的抗氧化酶的影响

以青藏高原的特有植物麻花艽为材料，研究麻花艽叶片抗氧化酶系统对增强UV-B辐射的响应。结果表明：在UV-B处理初期，麻花艽叶片SOD、POD的酶活性都能增加，但随着处理时间的延长，SOD、POD的活性呈现下降趋势。麻花艽叶片CAT的酶活性在UVB处理后下降明显，但作为清除叶绿体中H2O2的关键酶AP的酶活性表现为明显地增加趋势，说明在对麻花艽叶片增强UV-B辐射反应中AP起有着重要作用。MDA的含量随UV-B处理时间延长而增加，表明UV-B降低了细胞内活性氧自由基的清除能力，膜脂过氧化作用加剧，导致了对麻花艽叶片的伤害效应。

Effects of Enhanced UV-B Radiation on Antioxydative Enzymes in Gentiana straminea Leaves

Effects of enhanced UV-B radiation on the activities of SOD,POD,CAT and AP in Gentiana straminea Maxim.leaves,were studied.The results showed that in Gentiana straminea Maxim.leave the activities of superoxide dismutase (SOD) and peroxidase (POD) increased under the enhanced UV-B radiation,and decreased in long terms UV-B exposure;at the same time.in Gentiana straminea Maxim.leave the activities of catalase (CAT) droped and the activity of ascorbic acid-peroxidase (AP),as a key enzyme of H_2O_2 scavenging system in choloroplasts,enhanced under the enhanced UV-B radiation.It might be showed that AP was mostly useful in the effects of antioxydative enzyme by enhanced UV-B radiation in Gentiana straminea Maxim.leaves.The content of malonaldehyde (MDA) was markedly enhanced by long terms UV-B exposure in Gentiana straminea Maxim.leaves.It might be concluded that UV-B injury to membrane was correlated to activated oxygen accumulation which promoted lipid peroxidation,while excessive activated oxygen production might be caused by the inhibition of antioxydative enzyme.