低温胁迫下PEG对烟草幼苗膜脂过氧化作用的影响

低温胁迫下，烟草幼苗体内内源抗氧化剂（Car,AsA)含量显著下降，细胞膜透性增大，幼苗内超氧阴离子（O2^-）大量产生，丙二醛（MDA）积累，并随低温胁迫时间的延长而增加，膜脂过氧化作用加剧。过氧化氢酶（CAT）、超氧化物歧化酶（SOD）和过氧化物酶（POD）活性水平的变化也呈下降趋势。PEG浸种处理的烟草幼苗在低温下质相对透性降低，超氧阴离子含量显著低于对照，SOD，CAT和POD活性水平下降较缓，丙二醛的积累量也明显较对照低。PEG浸种处理后，抗坏血酸（AsA)和类胡萝卜素（Car)等内源抗氧化剂含量也相对提高。表明PEG处理能提高细胞膜的稳定性和膜脂过氧化的保护能力。

EFFECTS OF PEG ON MEMBRANE LIPID PEROXIDATIONIN TABACCO SEEDLINGS UNDER CHILLING STRESS

Tobacco seedlings were exposed to chilling stress to study the mechanism(s) of cold injury. The results indicated that under chilling stress, endogenous antioxidans like ascorbic acid (AsA) and carotenoid (Car) decreased and relative cell membrane permeability increased, and generation of O -. 2 and accumulation of MDA increased in the plants. With the lengthening the chilling treatment time, the activity of SOD, CAT and POD was enhanced and content of AsA and Car decreased. Such results suggested that injury by low temperature was related to the imbalance of activated oxygen metabolism in tobacco plants. The seedlings treated with PED showed lower relative plasmalemma permeability under chilling stress, and O - 2 production rate was lower than that of the control, the activity of SOD, CAT and POD increased while the accumulation MDA decreased and the contents of AsA and Car decreased at a lower rate, suggesting that PEG treatment may improve the stability of the plasmalemma and its protection ability against membrane lipid peroxidation.