高苇++王勇++张春祥

摘 要：本研究探讨侵染黄瓜的多主棒孢菌孢子悬液和粗毒素提取液对黄瓜主要防御酶系活性的影响，从生理生化水平揭示多主棒孢菌毒素在病原致病过程中的作用机理。在室内条件下测定多主棒孢菌孢子及其粗毒素悬液作用后，黄瓜植株体内防御酶系过氧化物酶（POD）、多酚氧化酶（PPO）和超氧化物歧化酶（SOD）的活性变化。结果表明：多主棒孢菌孢子和毒素悬液处理黄瓜叶片后，黄瓜植株体内POD酶和PPO酶活性呈现先增加后降低的趋势，粗毒素悬液作用下酶活力在24 h时可达到最大值；而在孢子悬浮液作用下酶活力在48 h时达到峰值，随后显著降低，120 h后低于未处理的对照。在病原菌初期诱导作用下，SOD酶活性逐渐升高在72 h时达到最大；毒素接种黄瓜叶片后，SOD酶活性在48 h达到峰值，达到峰值后2个处理的SOD酶活性显著降低但均高于对照。本研究证明多主棒孢菌粗毒素对黄瓜寄主防御酶活性与其病原真菌孢子的作用具有一定相似性，酶活性峰值增加比率相近，前者比后者增加峰出现早，毒素诱导作用后防御酶活性最终高于未接种处理，黄瓜对其侵染的抵抗力得以维持，而在孢子悬液的作用下寄主的抵抗力随着其侵染的扩展而降低。

关键词： 多主棒孢菌；粗毒素；防御酶系；活性

中图分类号： S642.2 文献标识码： A DOI 编码：10.3969/j.issn.1006-6500.2016.08.002

Abstract： The aim of this study is to explore the effects of spores and crude toxins of Corgnespora cassiicola on the activity of defensive enzymes of cucumber. It was revealed that the pathogenic mechanism of crude toxin of Corgnespora cassiicola in physiology and biochemistry level. The effects of spores and crude toxins of Corgnespora cassiicola on the activity of defensive enzymes （POD， PPO and SOD） of cucumber were detected under laboratory conditions. The resulted showed that the activity of POD and PPO enzymes first increased and then decreased. The activity of enzymes reached the maximum within 24 h under infected crude toxin；the activity of enzymes reached the peak value at 48 h after infecting conidia of Corgnespora cassiicola， then the value declined with increasing hours， and at finally it was lower than the treatment without infected. The activity of SOD enzymes reached the peak value at 72 h with infecting conidia of Corgnespora cassiicola， and at 48 h with infecting crude toxin of this pathogen. After this moment the values of SOD enzymes decreased significantly but still were higher than the value in control. The results of the study demonstrated that Corgnespora cassiicola crude toxin had similar effects on the defense-enzyme activity of cucumber as spores of this pathogen did， and changes of activity induced by crude toxin in cucumber seedlings was closely related to induced by spores. The resistant of cucumber was conducted with the crude toxin of Corgnespora cassiicola， but it was significantly decreased under the infection and extension of the spores of this pathogen.

Key words：Corynespora cassiicola；crude toxin；defensive enzymes； activity

黄瓜棒孢叶斑病，又名黄瓜靶斑病、黄瓜褐斑病，是一种世界性分布的病害，主要危害黄瓜叶片，在叶片上形成大量圆形或不规则的黄褐色病斑，发病严重时能引起黄瓜枯萎、早衰[1]。……