小菜蛾取食后上海青的保护酶活力变化

上海青遭受小菜蛾取食为害后，0.5小时内叶片的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)、多酚氧化酶(PPO)和总酚含量发生变化。就一天内的变化趋势而言，受害叶片的SOD、CAT、POD、PPO活力和总酚含量总体上比正常叶片低，但在15：00时，正常叶片的SOD、CAT和POD活力最低时，受害叶片的三种酶活力却明显上升，在11：00时，正常叶片PPO活力为最低值时，受害叶片的PPO活力达最高，这可能是过度胁迫造成的，正常叶片的PPO活力与总酚量负相关，但受害叶片不呈现这种关系，此外，受害植株的未受害叶的保护酶活力也不同程度地发生变化，可见上海青对小菜蛾的取食胁迫后保护酶的反应是系统性的。

The change of activities of protective enzymes in Chinese cabbage infested by diamondback moth, Plutella xylostella

The activities of SOD, CAT, POD,PPO and the content of phenol in the leaves of Chinese cabbage, Brassica chinensis, changed 0.5h after cabbage leaves infested by the larvae of diamondback moth (DBM), Plutella xylostella. The trend of the activity of SOD, CAT, POD, PPO and the quantity of phenol in damaged leaves within a day declined in comparison with the normal leaves. But the activity of SOD, CAT and POD increased obviously at 15:00 and PPO at 11:00 when the enzymatic activity of normal leaves was the lowest in a day, as might be caused by excessive stress. The content of total phenol and the activity of PPO were negatively correlated in normal leaves, but it was not the same case in damaged leaves. The enzyme activity of undamaged leaves in cabbage infested by DBM varied accordingly too. The results indicated that the physiological stress reaction of Chinese cabbage was systematical to insect feeding.