摘要： 对抗、感霜霉病两类黄瓜品种的萌动种子、子叶、不同叶位真叶及定位叶片感染霜霉病菌后叶内超氧化物岐化酶（SOD）、多酚氧化酶（PPO）和过氧化物酶（POD）活性的测定结果表明：抗病品种比感病品种萌动种子中的SOD活性高54.15%、PPO活性高62.14%;子叶中的SOD活性高35.51%，PPO活性高40.10%，POD活性高74.47%;不同叶位真叶内，除SOD活性为感病品种高于抗病品种131.52%外，PPO、POD活性仍分别高于感病品种12.93%和28.76%;定位叶片接种感染霜霉菌后，随接种时间的延续，PPO活性降低，而POD活性增加，SOD活性呈先降后升趋势，但前两种酶活性始终是抗病品种高于感病品种，与抗病性呈正相关，SOD活性始终是感病品种高于抗病品种，与抗病性呈负相关。

关键词: 黄瓜组织, 酶活性, 霜霉病, 抗性

Abstract: The activities of superoxide dismutase(SOD), peroxidase(POD) and polyphenol oxidase(PPO) in germinated seeds, cotyledons, true leaves on different nodes and the leaves inoculated with Pseudoperronospora(Berk. et Curt.) Rostov. of cucumber varieties with different resistance to downy mildew of cucumber were measured. The results showed that SOD activity in germinated seeds and cotyledons of resistant varieties were 54.15% and 35.51% higher than that of the susceptible varieties. SOD activity in true leaves on different nodes of resistant varieties was 131. 51% higher than that of the susceptible varieties. Activities of polyphenol oxidase in germinated seeds, cotyledons and true leaves on different leaf nodes of resistant varieties were 62. 14%, 60. 00%, and 12. 93% (mean of 3 leaf nodes) higher than that of the susceptible varieties respectively. Activities of prooxidase in cotyledon and true leaves on different nodes of resistant varieties were 74. 47% and 28. 76% higher than that of the susceptible varieties respectively. When the leaves on the second node was inoculated with Pseudoperonosis (Berk. et Curt.) Rostov, the activity of polyphenol oxidase decreased with increase of the time after inoculation (i. e. increase of disease index). However, activities of two enzymes in resistant varieties were higher than those of the susceptible varieties all time,activity of SOD was going down firstly and then rising, but that of the resistant varieties was always higher than that of the susceptible varieties.It was concluded that there was a negative correlation between the activity of SOD and resistance to downy mildew of cucumber, and there were positive correlations between the activities of polyphenol oxidase and prooxidase and the resistance to downy mildew of cucumber.

Key words: Cucumber tissue, Enzyme activity, Pseudoperonospora cubensis, Resistance

中图分类号: 

• S642.01