长春花感染黄龙病菌多酚氧化酶基因的表达及活性分析

Gene expression and activity of polyphenol oxidase from Catharanthus roseus infected by Candidatus Liberibacter asiaticus

【目的】分析长春花Catharanthus roseus受黄龙病菌Candidatus Liberibacter asiaticus侵染后多酚氧化酶(PPO)基因的表达及活性变化。【方法】根据不同作物多酚氧化酶基因PPO序列的相似性,筛选出长春花多酚氧化酶基因Pw PPO引物,PCR扩增得Pw PPO基因片段,运用qRT-PCR和生理生化方法分析长春花嫁接黄龙病芽后,不同时间长春花叶、主茎和根中Pw PPO基因的表达量和酶活性变化。【结果】长春花受黄龙病菌侵染后,叶、主茎和根中Pw PPO基因的表达分别在嫁接后30、35和40 d上调表达4.23、12.64和33.80倍,不同组织中Pw PPO基因上调表达的时间和幅度不同。染病长春花的叶、主茎和根中PPO活性分别在嫁接后30、35和45 d为对照的2.87、2.10和1.89倍。【结论】Pw PPO基因表达量与PPO活性成正比,与长春花抵抗黄龙病菌侵染的能力密切相关。

【Objective】To study gene expression and enzyme activities of polyphenol oxidase（ PPO） from periwinkle（ Catharanthus roseus） infected by Candidatus Liberibacter asiaticus.【Method】The gene fragment of periwinkle PPO（ Pw PPO） was obtained using PCR technique. Primers were designed according to the sequence similarity of PPO genes from different species. Expression and enzyme activities of Pw PPO were analyzed in leaves,center stems and roots of C. roseus infected by Ca. L. asiaticus at different days after inoculation using qRT-PCR and physiological and biochemical methods. 【Result】The expressions of Pw PPO were upregulated 4. 23,12. 64 and 33. 80 fold respectively in leaves,center stems and roots at 30,35 and 40 days after inoculation. The time and extent of the upregulated expressions of Pw PPO in different tissues were different. The PPO activities in leaves,center stems and roots of periwinkle infected by Ca. L. asiaticus were 2. 87,2. 10 and 1. 89 times respectively of healthy control at 30,35 and 45 days after inoculation respectively. 【Conclusion】Gene expression level of Pw PPO is proportional to PPO activity,and is related closely to the resistance ability of host periwinkle against Ca. L. asiaticus invasion.