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为了解太子参蚕豆萎蔫病毒2(Broad bean wilt virus 2,BBWV2)的遗传多样性及分子进化关系,本研究对5个不同地理来源的6份太子参病叶样品进行了BBWV2外壳蛋白(coat protein,CP)基因的RT-PCR扩增和克隆。序列分析结果表明,所得13条太子参BBWV2 CP基因序列均为1 345 bp,其核苷酸序列同一性在81.0%~99.0%之间,氨基酸序列同一性在93.5%~99.3%之间;核苷酸多样性为0.084 00;存在280个核苷酸多态性位点,其中232个为地域特异性位点;总变异数为278个,其中同义突变29个,异义突变249个。不同地理来源的太子参BBWV2分离物之间遗传分化程度较高,基因交流不频繁,遗传漂变可能导致分离物间明显的遗传分化。在系统进化树中,太子参分离物的聚类呈现出明显的地域特异性,江苏、贵州、湖南、福建分离物均聚类在I-a亚组,而山东分离物聚类在II-c亚组,遗传距离较远。研究表明,太子参BBW V2存在很高的遗传变异,基因突变是其产生遗传多样性的主要驱动力,而地理因素与其具有较高的核苷酸多样性密切相关。
In order to understand the genetic diversity and phylogenetic relationship of Broad bean wilt virus 2 (BBWV2), six coat protein samples from five geographic origins including coat protein , CP) gene by RT-PCR amplification and cloning. The results of sequence analysis showed that the sequences of 13 genes of BBWV2 CP gene were all 1 345 bp. The nucleotide sequence identities of BBWV2 CP gene ranged from 81.0% to 99.0%, and the identity of amino acid sequence ranged from 93.5% to 99.3% The nucleotide diversity was 0.08400. There were 280 nucleotide polymorphisms, of which 232 were site-specific. The total number of variation was 278, including 29 synonymous mutations and 249 synonymous mutations. Genetic differentiation of heterophilous BBWV2 isolates from different geographical origins is high, with less frequent gene exchange. Genetic drift may lead to obvious genetic differentiation among isolates. In the phylogenetic tree, the cluster of Pseudostellaria heterophylla isolates showed obvious regional specificity. Jiangsu, Guizhou, Hunan and Fujian isolates clustered in Ia subgroup while Shandong isolates clustered in II-c subgroup , Genetic distance. Studies have shown that there is a high genetic variation in P. ginseng BBW V2. Gene mutation is the main driving force for its genetic diversity, while geographical factors are closely related to its high nucleotide diversity.