南瓜蚜传黄化病毒基因组遗传多样性分析

Analysis of genomic genetic diversity of cucurbit aphid-borne yellows virus

【目的】研究南瓜蚜传黄化病毒(Cucurbit aphid-borne yellows virus,CABYV)的分子特征、遗传结构和进化机制,对于明确该病毒病在田间发生的流行规律和制定长期可持续的防控策略具有重要意义。【方法】从新疆阿克苏市随机采集了疑似感染CABYV的120份甜瓜叶片,采用RT-PCR方法进行病毒检测,序列采用MEGA 7.0构建系统发育树,使用DnaSP v5.10分析不同序列之间的遗传多样性,采用RDP v.4.31软件分析CABYV序列可能发生的重组事件。【结果】经RT-PCR验证,38个样品为CABYV阳性,检出率为31.67%。从这些阳性样品中分离、测序、克隆得到了一个新的CABYV-2分离物。该分离物基因组长度为5497 bp,编码6个开放阅读框。与NCBI数据库中的来自不同国家的23个CABYV分离物相比,CABYV-2与KR231942.1的同源性最高,与JF939812.1的同源性最低。进化树分析结果表明,24个分离物由于地理因素的不同被分为2个分支,其中CABYV-2与KR231942.1聚在一起,属于分支1。遗传多样性与中性检验结果说明CABYV存在高度变异且种群不断扩展。重组分析结果表明,有EU636992.1和KR231949.1两个重组事件,重组加剧了CABYV的变异。【结论】CABYV在我国分布广泛且种群不断扩展,成为瓜类植物生产的限制因素。CABYV新疆阿克苏市分离株与韩国分离株KR231942.1亲缘关系最近,与来自欧洲国家的分离株亲缘关系最远,分支1和分支2分离株之间存在较大的遗传差异,CABYV在不同宿主间的重组加剧了CABYV的变异,重组和负选择可能是影响CABYV遗传变异的重要原因。

[Objective]The present paper aimed to study the molecular characteristics,genetic structure and evolutionary mechanism of cucurbit aphid-borne yellows virus(CABYV),in order to clarify the epidemic pattern of the virus in the field and formulate long-term sustainable prevention and control strategies which is of great significance.[Method]120 melon leaves suspected to be infected with CABYV were randomly collected from Aksu city,Xinjiang.RT-PCR was used to detect the virus.MEGA 7.0 was used to construct phylogenetic tree,DnaSP v5.10 was used to analyze the genetic diversity among different sequences,and RDP v.4.31 software was used to analyze the possible recombination events of CABYV sequence.[Result]As verified by RT-PCR,38 samples were CABYV positive,and the detection rate was 31.67%.A new CABYV-2 was isolated,sequenced and cloned from these positive samples.The length of the genome was 5497 bp,encoding six open reading frames.Compared with 23 CABYV strains isolated from different countries in NCBI database,CABYV-2 had the highest homology with KR231942.1 and the lowest homology with JF939812.1.The results of evolutionary tree analysis showed that 24 isolates were divided into two branchesdue to different geographical factors,including CABYV-2 and KR231942.1 come together and belong to branch 1.The results of genetic diversity and neutral test showed that CABYV was highly variable and population was expanding.The results of recombination analysis showed that there were two recombination events,EU636992.1 and KR231949.1,which exacerbated the variation of CABYV.[Conclusion]CABYV was isolated from Aksu,Xinjiang and KR231942.1 from Korea had the closest genetic relationship and the farthest genetic relationship with isolates from European countries.There were great genetic differences between branch 1 and branch 2 i-solates.The recombination of cabyv among different hosts intensifies the variation of CABYV recombination and negative selection may be important reasons affecting the genetic variation of CABYV.