PEG渗透胁迫下玉米幼苗叶片保护酶活性昼夜变化

Diurnal Variation of Cell Defense Enzyme Activity in Leaves of Maize Seedling under Polyethylene Glycol-6000 Stress

[目的]了解逆境条件对植物体内保护酶活性昼夜变化的影响。[方法]用不同浓度聚乙二醇(PEG-6000)溶液研究渗透胁迫下玉米幼苗叶片电解质外渗率、丙二醛(MDA)含量和超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)的昼夜变化情况。[结果]一昼夜胁迫中,保护酶活性的变化不仅受PEG浓度和胁迫时间的影响,而且受光照的影响。随着光照时间和胁迫时间的延长,叶片电解质外渗率和MDA含量增加、SOD活性持续降低、POD和CAT活性的变化率则呈先增加后降低趋势;光照结束后,随着黑暗时间的延长,电解质外渗率和保护酶活性先接近对照水平,然后发生较大波动。[结论]玉米幼苗叶片的保护酶活性变化不仅受PEG浓度、胁迫时间的影响,而且受光照的影响。

[Objective]The research aimed to study the influence of stress on the diurnal variation of cell defense enzyme activity in plants.[Method]Effects of osmotic stress on the diurnal variation of electrolyte leakage and change in activities of the main antioxidant enzymes,inchuding superoxide dismutase（SOD）,peroxidase（POD） and catalase（CAT）,in leaves of maize seedlings were investigated with different concentrations of polyethylene glycol（PEG-6000） treatment.[Result]The results showed that the activity of protective enzymes not only be impacted by the PEG concentration and stress time,but also by light in one round the clock.As the illumination time and stress time prolong,electrolyte leakage and MDA content increased,SOD activity decreased,the activity of POD and CAT increased first and then decreased;As the prolong of darkness after light,electrolyte leakage and protective enzymes activity closed to the control level first and after that varied rather highly.It indicated that light exacerbated the balance of oxygen free radical damage,while darkness conduced its recovery;however,as the stress time prolong,plant hurted sharply,even leading to irreversible damage in the balance of oxygen free radical eventually.[Conclusion]The changes of cell defense enzyme activity in leaves of maize seedling were influenced by density of PEG,time of stress and illumination.