镧对UV-B胁迫下大豆幼苗膜脂过氧化影响:Ⅰ对CAT和POD的影响

Effect of Rare Earth on Membrane Lipid Peroxidation of Soybean Seedlings Under Supplemental UV-B Irradiation:ⅠIts Influence on CAT and POD Activities

采用水培实验方法研究了La对紫外辐射(UV-B,280～320nm)胁迫下大豆(Clycinemax)幼苗膜脂过氧化及CAT、POD等抗氧化酶的影响。结果表明,UV-B辐射(T1/0.15W·m-2和T2/0.45W·m-2)胁迫下,大豆幼苗质膜透性和MDA含量先升(胁迫期)后降(恢复段),CAT活性先增(1～5d)后减(6～11d),T1组POD活性在胁迫期逐渐升高,恢复期维持一较高水平后陡降,而T2组POD活性一直升高至第9d,而后略有下降。La的介入,使大豆质膜透性和MDA光致修复各时段变幅降低,La+T1及La+T2组2种酶活均大于UV-B组,表明La对CAT、POD等抗氧化酶有调控作用,减轻了UV-B辐射对其功能的损伤,增强了抗氧化酶清除活性氧能力,改善了活性氧代谢,降低了MDA浓度,维持了质膜正常透性,且对低剂量(T1)的防护效果优于高剂量(T2),进而在防御系统层面实现了La对UV-B辐射伤害大豆幼苗的防护效应。

Effects of lanthanum （La^3＋） on membrane lipid peroxidation and antioxidant enzymes such as CAT and POD of soybean seedlings under elevated ultraviolet-B radiation （UV-B：280-320 nm） at 15 μW·m^-2 and 45 μW·m^-2 level were investigated with hydroponics under laboratory conditions. The result showed that plasmolemma permeability and MDA content of soybean 3eedlings gradually increased under supplemental ultraviolet-B stress and then decreased after the removal of uhraviolet-B radiation. The dynamic of CAT activity was similar to that of plasmolemma permeability and MDA content. The activity of POD firstly increased, maintained a high level and fell down steeply when soybean seedlings were exposed to low dosage of UV-B radiation. However, POD activity of soybean seedlings under high level of UV- B radiation stresse rose all the time and declined slightly on the 7th day. With the mediation of La, during the period of light recovery the range of variation of plasmolemma permeability and MDA content declined, with the activities of CAT and POD higher than that of UV-B treatments, suggesting that the regulative effect of La on antioxidant enzymes such as CAT and POD alleviated the injury of UV-B radiation to their function, strengthened their capacities to scavenge reactive oxygen species （ROS）, improved the metabolism of ROS, diminished the concentration of MDA, maintained normal permeability of membrane, and that its protective effect against low UV-B radiation was superior to that of high UV-B radiation. So, the defensive effect of La on soybean seedlings under UV-B stress was carded out on the layer of defense system.