The nucleotide sequence and genome organization of Plasmopara halstedii virus.
The nucleotide sequence and genome organization of Plasmopara halstedii virus.
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DOI：
10.1186/1743-422x-8-123
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发表时间：
2011-03-17
期刊：
影响因子：
4.8
通讯作者：
Spring O
中科院分区：
文献类型：
--
作者：
Heller-Dohmen M;Göpfert JC;Pfannstiel J;Spring O
只有很少的卵菌病毒被详细研究过。在向日葵霜霉病病原菌halsteplplasmopara卵菌的不同分离株中发现了等长病毒粒子。然而，缺乏完整的核苷酸序列和基因组组织数据。对不同的halstedii分离株的病毒RNA进行核苷酸测序和病毒基因组分析。采用自上而下MALDI-TOF法测定病毒外壳蛋白n端序列。建立了两个单链RNA片段（RNA1和RNA2）的完整核苷酸序列。RNA1由2793个核苷酸（nt）和一个2745 nt的单开放阅读框（ORF1）组成。ORF1由一个18 nt的5‘非翻译区（5’ UTR）和一个30 nt的3‘非翻译区（3’ UTR）组成。ORF1含有RNA依赖性RNA聚合酶（RdRp）的基序，与大孢子疫霉病毒A （SmV A）和noddaviridae科病毒的RdRp相似。RNA2由1526 nt的3' poly(A)通道和1128 nt的第二ORF （ORF2）组成，ORF2编码单个病毒外壳蛋白（CP），由164 nt的5' UTR和234 nt的3' UTR组成。自上而下MALDI-TOF分析揭示了CP的n端序列，该n端序列代表ORF2内的一个区域，表明CP在体内发生了蛋白水解过程。该病毒的CP与SmV A和tombusvirus科病毒的CP相似。利用RNA1（约1.9 kb）和RNA2（约1.4 kb）片段分析不同分离株病毒粒子核苷酸序列的差异。无论宿主的病原类型、地理来源和对杀菌剂甲螨灵的敏感性如何，病毒序列变异均在0.3%以下。结果表明，在不同的halstedii分离株中存在单一和新的病毒类型。不显著的病毒序列变异表明，该病毒不能解释哈尔氏卵菌致病性的差异。
Only very few viruses of Oomycetes have been studied in detail. Isometric virions were found in different isolates of the oomycete Plasmopara halstedii, the downy mildew pathogen of sunflower. However, complete nucleotide sequences and data on the genome organization were lacking. Viral RNA of different P. halstedii isolates was subjected to nucleotide sequencing and analysis of the viral genome. The N-terminal sequence of the viral coat protein was determined using Top-Down MALDI-TOF analysis. The complete nucleotide sequences of both single-stranded RNA segments (RNA1 and RNA2) were established. RNA1 consisted of 2793 nucleotides (nt) exclusive its 3' poly(A) tract and a single open-reading frame (ORF1) of 2745 nt. ORF1 was framed by a 5' untranslated region (5' UTR) of 18 nt and a 3' untranslated region (3' UTR) of 30 nt. ORF1 contained motifs of RNA-dependent RNA polymerases (RdRp) and showed similarities to RdRp of Scleropthora macrospora virus A (SmV A) and viruses within the Nodaviridae family. RNA2 consisted of 1526 nt exclusive its 3' poly(A) tract and a second ORF (ORF2) of 1128 nt. ORF2 coded for the single viral coat protein (CP) and was framed by a 5' UTR of 164 nt and a 3' UTR of 234 nt. The deduced amino acid sequence of ORF2 was verified by nano-LC-ESI-MS/MS experiments. Top-Down MALDI-TOF analysis revealed the N-terminal sequence of the CP. The N-terminal sequence represented a region within ORF2 suggesting a proteolytic processing of the CP in vivo. The CP showed similarities to CP of SmV A and viruses within the Tombusviridae family. Fragments of RNA1 (ca. 1.9 kb) and RNA2 (ca. 1.4 kb) were used to analyze the nucleotide sequence variation of virions in different P. halstedii isolates. Viral sequence variation was 0.3% or less regardless of their host's pathotypes, the geographical origin and the sensitivity towards the fungicide metalaxyl. The results showed the presence of a single and new virus type in different P. halstedii isolates. Insignificant viral sequence variation indicated that the virus did not account for differences in pathogenicity of the oomycete P. halstedii.