胜红蓟上一种与双生病毒伴随的重组β卫星分子的鉴定

Identification of a recombinant geminivirus-associated betasatellite from Ageratum conyzoides

双生病毒是一类在全球范围内危害严重的单链环状DNA病毒。本研究从2017年采自云南的胜红蓟样品中(YN2017)获得了一条菜豆金色花叶病毒属病毒和一条β卫星的全基因组序列。该双生病毒的全长序列与烟草曲茎病毒的相似性最高,为99.60%,确定为烟草曲茎病毒的分离物。YN2017β卫星与中国胜红蓟黄脉β卫星的同源性最高,为90.8%。进一步分析发现,该β卫星的卫星保守区域(SCR)至富含腺嘌呤区(A-rich区)之间约1 kb的序列与中国胜红蓟黄脉β卫星相应序列的相似性高达97.2%;其包含的A-rich区上游与SCR之间约300 bp的序列与中国胜红蓟黄脉β卫星相应序列的相似性仅为70.2%,而与烟草曲茎β卫星相应序列的相似性最高,为97.3%。重组分析发现,所分离的β卫星是由中国胜红蓟黄脉β卫星和烟草曲茎β卫星重组产生。这是首次在中国发现由不同的β卫星重组产生的β卫星分子。

Geminiviruses are a group of single-stranded DNA viruses that cause severe losses to many crops worldwide.In this study,we determined the complete nucleotide sequences of a begomovirus and a betasatellite from an Ageratum conyzoides plant(YN2017)showing yellow vein and leaf curling symptoms in Yunnan.The begomovirus shared 99.60%sequence identity with Tobacco curly shoot virus(TbCSV)and thus was identified as an isolate of TbCSV.The YN2017 betasatellite shared the highest sequence identity(90.8%)with Ageratum yellow vein China betasatellite(AYVCNB).Further analysis of the betasatellite sequences showed that the sequences from the satellite conserved region(SCR)to the A-rich region shared 97.2%identity with the homologous sequences of AYVCNB,while the sequences between the SCR and the upstream A-rich region only shared 70.2%identity with that of AYVCNB.Instead,these sequences were more closely related(97.3%sequence identity)to the coordinated sequences of TbCSB.Recombination detection analysis showed that the betasatellite might result from the recombination of AYVCNB and TbCSB.This is the first report of a recombinant betasatellite that has arisen from betasatellites recombination in China.