文献中多采用生物体内实验方法来研究污染物对植物酶的诱导作用，但体内实验操作相对繁琐，耗时长，亟需采用一种快速、简便的体外实验方法来研究多环芳烃（ PAHs）等对植物酶的影响。采用植物体外实验方法，以三叶草（ Trifolium repens）为供试植物，研究了三叶草茎叶中多酚氧化酶（ PPO）对二环PAHs苊和四环PAHs芘的体外诱导响应。结果表明，ρ（苊）为0～39．68 mg·L－1时，三叶草茎叶PPO活性随苊污染浓度增大而升高，表现为诱导效应；ρ（芘）为0～0．16 mg·L－1时，PPO活性随芘污染浓度增大呈先升高后降低趋势，表现为先诱导后抑制效应。三叶草茎叶PPO对苊和芘的体外污染的敏感性响应顺序为苊＜＜芘，与其自身毒性顺序一致。采用体外实验方法可快速、有效、简单地评价PAHs对植物PPO的诱导效应。%The knowledge of impacts of polycyclic aromatic hydrocarbons ( PAHs) on enzyme activities in plant will be of great significance to risk assessment of PAH contamination. However, little information is hitherto available in literature on in vitro experiment to study PAH⁃influenced enzyme activity in plant. Impacts of PAHs on phenol oxidase ( PPO) activity in shoots of clover ( Trifolium repens) were investigated in vitro. Acenaphthene and pyrene were used to represent PAHs. PPO activity in clover shoots was enhanced steadily with rising acenaphthene concentration from 0 to 39.68 mg·L-1 , indi⁃cating an inductive effect of acenaphthene on PPO activity. In contrast, PPO activity increased first and decreased thereaft⁃er with increasing pyrenecon centration from 0 to 0.16 mg·L-1 , suggesting an inductive effect in the early phase and an inhibition effect in the late phase. It was observed that PPO in clover shoots was more sensitive to acenaphthene stress than to pyrene stress, which is consistent with the trend of acenaphthene being higher than pyrene in toxicity. All the results of this work indicate that in vitro experiment may be a fast, simple and effective means to evaluate impacts of PAHs on PPO activity in plants.
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