C02倍增对渗透胁迫下小麦叶片抗氧化酶类及细胞程序性死亡的影响

经渗透胁迫后 ,CO2 倍增条件下小麦叶片的SOD、POX和CAT的活性均显著高于对照 ,上升或稳定时期较长 ;在渗透胁迫后期MDA含量和电解质泄露率增加较慢 ,显著低于对照 ;H2 O2 含量一直高于对照但进行PEG胁迫后增长较慢。CO2 倍增条件下 ,小麦细胞出现DNA梯的时间较晚而且持续的时间较长 ,DNA梯出现时抗氧化酶和H2 O2 处于相对稳定状态。结果表明在渗透胁迫下CO2 倍增使小麦的抗氧化能力增强从而减轻了对细胞膜和DNA的损伤 ,并且干旱条件下小麦的细胞程序性死亡可能是由于细胞内氧化过强所致

Effects of Doubled CO2 Concentration on Antioxidant Enzymes and Programmed Cell Death of Wheat Leaves Under Osmotic Stress

The effects of doubled CO2 concentration (700 μmol/mol ) on antioxidant enzymes and programmed cell death in wheat under osmotic stress were studied. The results are as follows: The activities of SOD, POX, and CAT in wheat leaves under doubled CO2 were markedly higher than those of control while theincreasing period and steady period were longer (Fig.1). The H2O2 content of the leaves growing under high CO2 concentration was higher than the control and after PEG6000 treatment, the increase of MDA, electrolyte leakage and H2O2 increased slightly than in the control (Figs.2,3). The DNA ladders were observed from three to five days after PEG treatment in control and from four to seven days in control (Fig.4). During the time when DNA ladders appeared, the activities of SOD, POX and CAT and the MDA and H2O2 contents were all nearly steady. The results indicated that prorammed cell death was enhanced by active oxygen and alleviated by antioxidant enzymes and elevated CO2 could enhance the functioning of the antioxidant system to increase the tolerance to osmotic stress.