水分胁迫对玉米叶片活性氧清除酶类活性的影响

Effects of Water Stress on the Activities of Active Oxygen Exterminating Enzymes of Maize Leaves

用培养于不同浓度聚乙二醇溶液中的玉米幼苗叶片切段研究了水分胁迫对叶片内活性氧清除酶类活性的影响，结果表明，水分胁迫引起叶绿素和蛋白质含量的迅速下降及脯氨酸水平的增加；过氧化氢酶（ＣＡＴ）活性开始时随胁迫时间而增强，而后下降，进一步加强胁迫时过氧化氢酶（ＣＡＴ）受抑程度取决于胁迫强度；水分胁迫引起叶片中超氧化物歧化酶（ＳＯＤ）活性迅速增强；轻度水分胁迫时叶片内抗坏血酸过氧化物酶（ＡＰＯＸ）活性增强，但重度胁迫时却下降；在所有水分胁迫条件下，谷胱甘肽还原酶（ＧＲ）活性均增强。重度水分胁迫下脂质过氧化作用增强，但轻度胁迫下几乎无此变化。这些不同参数的变化取决于水分胁迫强度。ＳＯＤ和ＧＲ活性随水分胁迫加剧而增强可能是由于逆境蛋白合成加强所致。过氧化氢（Ｈ２Ｏ２）降解系统效能的下降可能是水分胁迫下叶片中发生氧化伤害的原因。

Water stress caused a forter decline in the chlorophyll and protein contents and increase in the level of proline relative to the controls. Catalase activities initially increased with time and then declined in the control leaf segments and imposition of water stress prevented the incease to different degrees depending upon the degree of stress.Water stress also caused a rapid increase in the activity of superoxide dismutase (SOD).Ascorbate peroxidase (APOX) aetivity increase (GR) activity increased under all degrees of water stress studied as compared to the control. Lipid peroxidation was enhanced under severe water stress conditions but not under light water stress.The changes in the different items in this study are dependent upon the degrees of water stress.The increases in the activities of SOD and GR in response to water stress are probably due to the adverse circumstance synthesis of enzymatic proteins. Decline in the efficacy of the H2O2 decomposing system is probably responsible for oxidative damage occurring in water stressed leaves.