红树叶片衰老过程中活性氧和保护酶活性的变化

测定了红树植物木榄(Bruguiera gymnorrhiza)和秋茄(Kandelia candel)幼叶、成熟叶和老叶间活性氧和三种细胞保护酶活性的变化。结果表明，在叶片衰老过程中，丙二醛和H2O2含量显著提高，超氧化物自由基产生速率加快，表明红树叶片衰老中膜脂过氧化作用增强，并且与H2O2和超氧化物自由基含量的上升相关。在3种细胞保护酶中，超氧化物歧化酶(SOD)活性逐渐降低，过氧化物酶(POD)活性显著提高，过氧化氢酶(CAT)活性在叶片成熟过程中增高，随着衰老而急剧降低，细胞保护酶酶活的变化直接影响了叶片衰老过程中活性氧代谢的平衡。

Changes to activated oxygen and protective enzyme acticity in mangrove plant leaf during senescence

Changes of membrane lipid peroxidation,superoxide free anion generation rate,hydrogen peroxide(H 2 O 2 )content,and activity of some protective enzymes such as superoxide dismutase(SOD),peroxidase(POD),catalase(CAT)were measured in mangrove plant Kandelia candel and Bruguiera gymnorrhiza leaf during senescence.When the leaf grew from the tender stage to the senescence stage,malondialdehyde(MDA)and H 2 O 2 content increased evidently,superoxide free anion generation rate was also gradually raised,showing that membrane lipid peroxidation was enhanced during the leaf growth course,furthermore that itwas related to the raise of H 2 O 2 and superoxide free anion in the leaf.Among these three protective enzymes,SOD activity gradually decreased,while POD activity increased remarkably during growth course.CAT activity increased as the leaf matured,dropping sharply during senescence.Protective enzyme activity in the leaf had an immediate influence on the balance of activated oxygen metabolism.