柑橘衰退病毒侵染对寄主植物同工酶及酸性病程相关蛋白表达的影响

Effect of Citrus tristeza virus on the expression of isozymes and sour pathogenesis-related proteins in citrus plants

以柑橘衰退病毒(Citrus tristeza virus,CTV)不同致病力株系接种寄主植物,比较分析了寄主植物体内过氧化物酶(peroxidase,POD)和多酚氧化酶(polyphenol oxidase,PPO)活性变化特点。结果表明,该病毒侵染对这2种酶活性的影响因寄主品种和CTV株系而异,CTV强毒和弱毒株系侵染均导致墨西哥莱檬植株中POD活性明显降低;在甜橙上,CTV强毒株系接种植株中POD活性则显著性提高,而弱毒株系接种对POD的活性无明显影响;在对该病毒具有较高抗性的枳壳中,接种CTV不同株系对POD活性均无明显影响。而在接种强毒株系N25的墨西哥莱檬中PPO活性有所增强,在枳壳上则表现为接种植株的PPO活性降低,在甜橙上PPO活性无明显的变化。POD、PPO和酯酶(esterase,EST)同工酶酶谱分析的结果显示,CTV弱毒株系接种枳壳后诱导产生了2条新的EST同工酶谱带,而在其他CTV接种植株上均未诱导表达新的POD、PPO及EST酶谱。酸性病程相关蛋白分析结果显示,CTV强毒株系在甜橙上诱导产生有6条明显的酸性病程相关蛋白条带。

Citrus tristeza virus （CTV） is one of the most severe pathogens of citrus. In this study,the activities of the peroxi-dase （POD） and polyphenol oxidase （PPO） in citrus leaves infected by CTV mild and severe strains were examined,which will provide some useful information on the biochemical changes in hosts during the interaction between the virus and host plants. Results showed that the effect of CTV infection on activities of these enzymes was depended on the combinations of citrus species and CTV strains. The activity of POD was decreased in leaves of Mexican lime （Citrus aurantifolia）infected by both CTV serve and mild strains,increased in leaves of sweet orange （C. sinensis） infected by CTV severe strains. However,in Poncirus trifoliate,it was not affected by any analyzed CTV strains. Meanwhile,the PPO activity was increased in leaves of Mexican lime infected by a CTV severe strain N25 and decreased in CTV-infected Poncirus trifoliata and not affected in sweet orange. The isozyme spectra of POD,PPO and esterase （EST）were also analyzed in CTV-infected sweet orange and Poncirus trifoliate. Two isozyme bands of EST were induced by a CTV mild strain in Poncirus trifoliata and no induced isozyme spectrum was detected in other inoculated citrus plants. The sour pathogenesis-related proteins （PRs） were extracted from leaves of sweet orange and P. trifoliate inoculated with CTV severe strain N25 and mild strain N4. It was found that the infection of CTV strain N25 induced expression of 6 sour PRs.