UV-B辐射增强对红松幼苗针叶脂质过氧化及抗氧化系统的影响

Effects of Elevated UV-B Radiation on Lipid Peroxidation and Antioxidant System in Needles of Pinus koraiensis seedling

以盆栽3年生红松实生苗为材料,分为CK(对照)、T1(+3.25μW·cm-2UV-B辐射)、T2(+6.51μW·cm-2UV-B辐射)及T3(+9.76μW·cm-2UV-B辐射)4个处理,研究环境UV-B辐射增强对红松叶片自由基含量、脂质过氧化程度及抗氧化系统的影响。结果表明:UV-B辐射增强显著提高红松针叶内羟基自由基(·OH)、过氧化氢自由基(H2O2)和MDA含量(P<0.05),T3处理下叶片的H2O2(149.05mmol·g-1)和MDA(12.56μmol·g-1)含量最高;UV-B辐射增强诱导过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)和超氧化物歧化酶(SOD)活性升高,显著降低过氧化物酶(POD)活性(P<0.05);抗氧化物质中可溶性蛋白含量随UV-B胁迫程度加强而显著增加(CK为0.17mg·g-1,T3处理为0.26mg·g-1),而各UV-B辐射增强处理均降低了类胡萝卜素和类黄酮含量。各生理指标相关分析结果表明:红松针叶内可溶性蛋白含量与自由基、MDA含量间存在极显著的正相关关系(P<0.01);·OH含量与类胡萝卜素、类黄酮含量间存在极显著的负相关关系(P<0.01)。研究证实UV-B辐射增强通过产生大量的自由基对红松幼苗的生理代谢产生影响,而红松幼苗通过提高抗氧化酶(CAT,APX,SOD)的活性和蛋白质的含量来抵抗UV-B辐射引起的损伤,但其防御机制并不能有效地缓解这个伤害。

The 3-year-old pot-cultured Pinus koraiensis seedlings were used in this experiment.The seedings were treated with the following treatments;CK（Control）,T1 treatment（3.25 μW·cm-2 UV-B radiation）,T2 treatment（6.51 μW·cm-2 UV-B radiation） and T3 treatment（9.76 μW·cm-2 UV-B radiation）.Effects of UV-B radiation on the concentration of free radical,the degree of lipid peroxidation and antioxidant system in needles of P.koraiensis were determined after 40 days of UV-B treatment.The results showed that the elevated UV-B radiation significantly increased concentrations of hydroxyl radical（·OH）,hydrogen peroxide radicals（H2O2） and malondialdehyde（MDA）（P 0.05）.The concentrations of H2O2（149.05 mmol·g-1） and MDA（12.56 μmol·g-1） were maximal under T3 treatment.The elevated UV-B radiation induced the activities of catalase（CAT）,ascorbate peroxide（APX）,and superoxide dismutase（SOD）,but significantly decreased the activity of peroxidase（POD）（P 0.05）.Concentration of soluble protein was increased with exposure to UV-B radiation（CK treatment was 0.17 mg·g-1,while T3 treatment was 0.26 mg·g-1）.Carotenoid and flavonoid were decreased significantly by all UV-B radiations treatments.Simultaneously,the results of correlation analysis showed that the concentration of soluble protein had significant positive correlations with the concentrations of free radical and MDA（P 0.01）,and the concentration of hydroxyl radical had significant negative correlations with the concentrations of carotenoid and flavonoid（P 0.01）.This study demonstrated that the supplemental UV-B radiation increased the concentration of free radical and affected the physiological metabolism in needles of P.koraiensis seedlings.Simultaneously,P.koraiensis was able to increase the activities of CAT,APX,SOD and the concentration of soluble protein against oxidative stress injury caused by supplemental UV-B radiation,but the defense mechanism was not efficient enough to prevent the UV-B induced damage.