侵染白术的大豆花叶病毒的全基因序列测定及分析

大豆花叶病毒(soybean mosaic virus,SMV)是影响大豆产量与质量的重要病原体,且自然寄主范围窄。本研究对疑似感病白术叶片进行非序列依赖性扩增(sequence-independent amplification,SIA)检测,结果表明,感病白术为SMV侵染,并命名为SMV-Am。为明确其基因组结构特征及系统进化关系,本研究利用双链RNA(double-stranded RNA,dsRNA)提取、RT-PCR及RACE技术对其进行全基因组扩增,并进行生物信息学分析。结果表明,SMV-Am基因组全长9 587 nt,具有显著的马铃薯Y病毒属(Potyvirus)基因组结构特征;核苷酸与氨基酸序列相似性分析表明,SMV-Am与来自中国的SMV-Liaoning分离物相似性最高,核苷酸与氨基酸序列相似性分别为96.57%和98.86%;系统进化分析也显示与SMV-Liaoning分离物亲缘关系最近;对SMV-Am蛋白序列进一步分析发现,存在与功能位点相关的氨基酸突变,经I-TASSER和PyMOL软件进行蛋白建模分析,发现SMV-Am的P1、HC-Pro、P3、6K2、NIa-Pro、NIb蛋白结构均发生不同程度的变化,且P1蛋白最明显;重组分析结果显示,在SMV-Am基因组的6 560~8 950 nt位置存在重组事件,其主要亲本和次要亲本分别为SMV-XFQ012(GenBank登录号:KP710875.1)和SMV-pCB301-SC15(GenBank登录号:MH919386.1)。这是SMV侵染白术的首次报道,研究结果有望为防范SMV病害在白术上爆发流行以及防治提供科学依据。

Identification and Analysis of Complete Genomic Sequences of Soybean Mosaic Virus Isolates from Atractylodes macrocephala Koidz

Soybean mosaic virus (SMV) is a critical pathogen that reduces the soybean yield and seed quality worldwide,and SMV has a restricted natural host range. In this study, we used sequence-independent amplification (SIA) methods to identify the viruses that may cause the Atractylodes macrocephala Koidz disease. Results revealed that there is SMV in diseased Atractylodes macrocephala leaves, and we named this isolate as SMV-Am. To further characterize the genomic structural and phylogenetic relationships of SMV-Am, genomic dsRNA was extracted, and the genomic sequence was amplified by RT-PCR and RACE. The results of bioinformatics analysis showed that the genomic RNA of SMV-Am is 9587 nucleotides in length, which conforms to the typical characteristics of Potyvirus. According to the sequence alignment of complete nucleotide sequences, SMV-Am showed the highest level of nucleotide homology and amino acid sequences to SMV-Liaoning, 96.57% and 98.86%, respectively. In addition, phylogenetic analysis based on the nucleotide sequences of other SMV isolates of SMV-Am revealed that SMV-Am was most closely related toSMV-Liaoning. Then, the SMV-Am protein was further analyzed by I-TASSER and PyMOL software, revealing that the key amino acid mutations led to the structural changes of P1, HC-Pro, P3, 6K2, NIa-pro and NIb proteins, with P1 the most obvious. Finally, recombination has been detected at the position of 6560-8950 nucleotides, the main parent is the isolate SMV-XFQ012 (accession number KP710875.1), and the secondary parent is isolate SMV-pCB301-SC15 (accession number MH919386.1). This study is the first report of SMV in Atractylodes macrocephala Koidz, and these results are expected to provide a scientific basis for the prevention and control of SMV infection on Atractylodes macrocephala Koidz.