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甘蔗花叶病毒(Sugarcane mosaic virus,SCMV)是引起我国玉米矮花叶病的主要病毒。本文从山东泰安采集到2个表现矮花叶症状玉米样品的分离物(命名为DWK1和DWK2),通过RT-PCR扩增全基因组片段并测定了其序列(GenBank登录号分别为KU171814和KU171815)。序列分析结果表明,DWK1和DWK2基因组全长分别为9 575和9 576个核苷酸(nucleotides,nt),开放阅读框均为9 192 nt,编码3 063个氨基酸的多聚蛋白。DWK1和DWK2的全基因组核苷酸一致率为81.7%,DWK1与山西分离物SX(AY569692)的核苷酸一致率最高,为90.9%;DWK2与河北分离物BD8(JN021933)核苷酸一致率最高,达99.4%。二者在系统进化树中分别被聚类到Ⅰ组和Ⅳ组。重组分析发现,DWK1是HN(AF494510)、Guangdong(AJ310105)和BD8 3个分离物的重组体。选择压力分析表明,SCMV 11个蛋白的dN/dS值都小于1,均处于负选择,但在P1、P3和CP中存在正选择位点。本研究结果可为甘蔗花叶病毒株系的监测及防控提供理论指导。
Sugarcane mosaic virus (SCMV) is the major virus that causes maize dwarf mosaic disease in China. In this paper, two isolates (named as DWK1 and DWK2) were collected from Taian, Shandong Province, China. The whole genome fragments were amplified by RT-PCR and their sequences were determined (GenBank accession numbers KU171814 and KU171815, respectively) . Sequence analysis showed that the full length of DWK1 and DWK2 genomes were 9 575 and 9 576 nucleotides, respectively. The open reading frame was 9 192 nt and encoded a protein of 3 063 amino acids. The nucleotide identical rate of DWK1 and DWK2 was 81.7%, and that of DWK1 and Shanxi isolate SX (AY569692) was 90.9%, and that of DWK2 and Hebei isolate BD8 (JN021933) Highest, up to 99.4%. The two were clustered into Ⅰ and Ⅳ groups respectively in the phylogenetic tree. Recombinant analysis found that DWK1 is a recombinant of HN (AF494510), Guangdong (AJ310105) and BD8 three isolates. Selective pressure analysis showed that all 11 SCMV proteins had negative dN / dS values of less than 1, and negative selection, but positive selection sites were found in P1, P3 and CP. The results of this study may provide theoretical guidance for the monitoring and control of sugarcane mosaic virus strains.