【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PwPPO引物，PCR扩增得PwPPO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PwPPO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PwPPO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PwPPO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】PwPPO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 frag-ment of periwinkle PPO ( PwPPO) was obtained using PCR technique .Primers were designed according to the sequence similarity of PPO genes from different species .Expression and enzyme activities of PwP-PO 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 expres-sions of PwPPO 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 PwP-PO 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 PwPPO is proportional to PPO activity, and is related closely to the resistance ability of host periwinkle against Ca.L.asiaticus invasion.
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