达乌里胡枝子抗氧化防御系统对干旱及增强UV-B辐射的动态响应

摘要

以达乌里胡枝子(Lespedeza davurica)为研究对象,通过对照、中度干旱以及干旱与增强UV-B辐射复合处理,对其超氧阴离子(O2-)、丙二醛(MDA)和抗氧化剂含量及抗氧化酶活性的动态变化进行研究,探讨其抗氧化能力及膜脂过氧化的动态响应.结果表明:与单因子干旱胁迫相比,复合胁迫使超氧化物歧化酶(SOD)和过氧化氢酶(CAT)活性降低,抗坏血酸过氧化物酶(APX)及过氧化物酶(POD)活性升高,其中低强度UV-B辐射与干旱复合胁迫使SOD活性极显著低于单因子干旱胁迫下的(P＜0.01),POD活性随UV-B辐射强度增加而降低,APX和CAT活性随UV-B辐射强度增加而增加.与单因子干旱胁迫相比,复合胁迫使抗坏血酸(AsA)含量增加,且随UV-B辐射强度的增加先增加后降低；使叶绿素(Chl)和类胡萝卜素(Car)含量降低,随UV-B辐射强度增加而降低.低强度UV-B辐射与干旱复合胁迫前6d花青素含量极显著高于对照(P＜0.01).复合胁迫前期,MDA和O2-含量均比单因子干旱胁迫的低,后期则不同.隶属函数综合评价得出,中度干旱以及复合胁迫均能提高达乌里胡枝子的抗氧化能力,且与干旱胁迫相比,低强度UV B辐射与干旱复合胁迫下其抗氧化能力较高,而高强度UV-B辐射与干旱复合胁迫下则较低.%The effects of drought and enhanced UV-B radiation on the antioxidant defense system and membrane lipid peroxidation in Lespedeza davurica were investigated. Compared with the single-stress of drought, the co-stresses of drought and enhanced UV-B radiation decreased the activities of superoxide dis-mutase (SOD) and catalase (CAT) , and increased the activities of ascorbate peroxidase (APX) and peroxi-dase (POD). SOD activity under the co-stresses of drought and low UV-B radiation intensity was significantly lower than that under the single-stress of drought. With the increase of UV-B radiation intensity under co-stresses, POD activity decreased while activities of APX and CAT increased. Compared with the single-stress of drought, the co-stresses of drought and different UV-B radiation intensities increased ascorbic acid (AsA) content and decreased the contents of chlorophyll (Chi) and carotenoid (Car). With the increase of UV-B intensity under co-stresses, AsA content initially increased then decreased while the contents of Chi and Car decreased. During the first six days of the co-stresses of drought and low UV-B radiation intensity, anthocyanin content significantly increased compared with control. During the early stage of the co-stresses of drought and enhanced UV-B radiation, the contents of malonaldehyde (MDA) and O2-decreased compared with the single-stress of drought. Comprehensive evaluation according to subordinate function indicated that both single-stress of drought and co-stresses could increase the antioxidant ability of Lespedeza davurica , and the co-stresses of drought and low UV-B intensity improved antioxidant ability more.