Changes of the anti-oxidative enzyme systems and reactive oxygen species (ROS) of Hibiscus tili-aceus, Thespesia populnea , Hernandia nymphii folia , Clerodendrurn inerme and Pluchea indica at divergent habitats ( intertidal and inland) were surveyed. The results showed that O2 production rate was typically higher at inland in leaves of H. Tiliaceus and C. Inerme than at intertidal populations , and an abrupt rise of H2O2 content occurred in the leaves of H. Nymphii folia at inland. Therefore, the activities of su-peroxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (POD) and glutathione reductase (GR) increased in the leaves of H. Tiliaceus, C. Inerme and H. Nymphii folia at inland, but with different patterns, T. Populnea rapidly triggered antioxidant defense at intertidal, H2O2 level declined correspondingly. P. Indica up-regulated antioxidant enzymes in ASC-GSH cycle, SOD, POD, GR, to scavenge active oxygen species, therefore, P. Indica maintained higher capacity to detoxify O2- production rate at inland. The strategies of antioxidant defense ware different among mangrove associate species at divergent habitats. In conclusion, activity of the anti-oxidative enzyme systems of mangrove associate species at inland was typically higher than at intertidal populations (especially POD, GR). Indicating that the selection pressure form environmental stress resulted in the responses of habitat adaptability of mangrove associate species. Mangrove associate leaves up-regulated antioxidant enzymes under various environmental stresses (high temperature, radiation and drough) at inland, thus limited environmental stresses induced lipid peroxide and membrane permeability, which contributed integrity maintenance and tolerance of mangrove associates.%选取5种半红树植物,研究了其在不同生境(潮间带和陆生)抗氧化防御系统的变化.结果表明,陆生的黄槿、许树O-2 产生速率和莲叶桐H2O2含量均显著的高于其潮间带居群,从而使这3种半红树叶片中抗氧化酶类(SOD、APX、CAT、POD和GR)活性均高于其潮间带居群.而处于潮间带杨叶肖槿、阔苞菊(除SOD外)的SOD、APX、CAT活性显著高于其陆生居群,此时,H2O2含量要显著低于其陆生居群,而陆生的阔苞菊居群SOD、POD、GR活性高于其潮间带居群,因此,O-2产生的速率显著低于其潮间带居群.不同树种对不同生境有着不同抗氧化防御策略,总的趋势是,陆生的半红树抗氧化酶活性均要高于其潮间带居群,尤其是POD、GR活性在5种半红树中均显著高于其潮间带居群,暗示环境胁迫造成的选择压力导致半红树植物适应性的反应.高温、高光照、干旱是对陆生半红树的逆境胁迫,因此,上调抗氧化酶活性,以降低逆境对半红树的膜脂过氧化,减少电解质外渗,最终提高了半红树的抗逆性.
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