以采自广东、广西、海南、云南、四川、贵州等6个地区共300份感染柑橘黄龙病菌的DNA样本作为试验材料，通过PCR技术对黄龙病菌携带的3种类型原噬菌体基因进行特异扩增、测序，利用相关生物信息学软件进行遗传多样性分析。结果共鉴定出8种原噬菌体组合;携带单一原噬菌体类型的黄龙病菌株为6个地理种群的优势菌株，占比53。3％，其中以Type 2型为主;3类原噬菌体基因位点中A+T含量均高于G+C，表现出AT偏好特点;重组分析结果显示黄龙病菌间无重组信号，表明未发生重组事件;基因流Nm值均大于1，说明黄龙病菌在各种群中基因交流频繁;中性检验结果显示Tajima'sD、Fu and Li's D、Fuand Li'sF值均小于0，表明黄龙病菌种群存在过历史扩张。
Genetic Diversity Analysis of Candidatus Liberibacter Asiaticus Based on Different Types of Prophage
To explore the geographical distribution and genetic variability of Candidatus Liberibacter asiaticus(CLas)harboring diverse prophage types in China,300 CLas DNA samples extracted from leaf petioles of CLas infected citrus were collected from six provinces:Guangdong,Guangxi,Hainan,Yunnan,Sichuan and Guizhou.And surveyed for Type 1,Type 2 and Type 3 prophages by specific PCR,then sequenced,and subjected to genetic diversity analysis employing relevant bioinformatics software.The results showed that the presence of eight distinct prophage combinations among the six geographically diverse populations.Notably,the prevalence of CLas strains carrying a single prophage type was dominant,accounting for 53.3％of the samples,with Type 2 prophage being the most prevalent.Analysis of the three prophage gene loci demonstrated a higher content of A+T relative to G+C,indicating an AT preference.Recombination analysis indicated an absence of recombination signals,suggesting the absence of recombination events.The Nm value of gene flow is exceeded 1,indicating frequent gene exchange among different CLas groups.The results of the neutral test,characterized by Taj ima's D,Fu and Li's D,Fuand Li's F values,all being less than 0,indicated a historical expansion within the CLas population.
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