Rumbou Artemis, Candresse Thierry, von Bargen Susanne, Büttner Carmen
Faculty of Life Sciences, Albrecht Daniel Thaer-Institute of Agricultural and Horticultural Sciences, Humboldt-Universität zu Berlin, Berlin, Germany.
UMR 1332 Biologie du Fruit et Pathologie, INRAE, University of Bordeaux, UMR BFP, Villenave-d'Ornon, France.
Front Microbiol. 2021 Jan 8;11:621179. doi: 10.3389/fmicb.2020.621179. eCollection 2020.
While the focus of plant virology has been mainly on horticultural and field crops as well as fruit trees, little information is available on viruses that infect forest trees. Utilization of next-generation sequencing (NGS) methodologies has revealed a significant number of viruses in forest trees and urban parks. In the present study, the full-length genome of a novel has been identified and characterized from sycamore maple () - a tree species of significant importance in urban and forest areas - showing leaf mottle symptoms. RNA-Seq was performed on the Illumina HiSeq2500 system using RNA preparations from a symptomatic and a symptomless maple tree. The sequence assembly and analysis revealed the presence of six genomic RNA segments in the symptomatic sample (RNA1: 7,074 nt-long encoding the viral replicase; RNA2: 2,289 nt-long encoding the glycoprotein precursor; RNA3: 1,525 nt-long encoding the nucleocapsid protein; RNA4: 1,533 nt-long encoding the putative movement protein; RNA5: 1,825 nt-long encoding a hypothetical protein P5; RNA6: 1,179 nt-long encoding a hypothetical protein P6). Two independent NGS sequencing runs from the same symptomatic maple tree detected the same genome segments. For one of these sequencing runs the cDNA library was prepared using a primer targeting the conserved genome terminal region, known to be shared between emaraviruses genome segments. We suggest, therefore, that the six identified genome segments represent the complete genome of a novel emaravirus from maple, which we tentatively name maple mottle-associated virus (MaMaV). Phylogenetic and sequence homology analyses place this virus on the distinct "subgroup a" clade within the genus along with - among others - rose rosette virus, emaravirus 2, and fig mosaic virus. Validation RT-PCR assays performed on symptomatic and non-symptomatic trees suggest that MaMaV may be the symptom-inducing virus in the diseased trees. To our knowledge, this is the first time an is described from maple and is fully genetically characterized. With the discovery of MaMaV, the genus comprising negative-sense single-stranded viruses with very divergent genomes - that were until recently overlooked - has substantially increased counting 22 established and putative members.
虽然植物病毒学的重点主要是园艺作物、大田作物以及果树，但关于感染林木的病毒的信息却很少。利用新一代测序（NGS）方法已在林木和城市公园中发现了大量病毒。在本研究中，从悬铃木（一种在城市和森林地区具有重要意义的树种）中鉴定并表征了一种新型病毒的全长基因组，该悬铃木表现出叶片斑驳症状。使用来自一棵有症状和一棵无症状枫树的RNA制剂，在Illumina HiSeq2500系统上进行了RNA测序。序列组装和分析显示，有症状样本中存在六个基因组RNA片段（RNA1：7074 nt长，编码病毒复制酶；RNA2：2289 nt长，编码糖蛋白前体；RNA3：1525 nt长，编码核衣壳蛋白；RNA4：1533 nt长，编码假定的运动蛋白；RNA5：1825 nt长，编码假定蛋白P5；RNA6：1179 nt长，编码假定蛋白P6）。对同一棵有症状的枫树进行的两次独立NGS测序运行检测到相同的基因组片段。对于其中一次测序运行，使用靶向保守基因组末端区域的引物制备了cDNA文库，已知该区域在纤毛病毒基因组片段之间共享。因此，我们认为所鉴定的六个基因组片段代表了来自枫树的一种新型纤毛病毒的完整基因组，我们暂时将其命名为枫树斑驳相关病毒（MaMaV）。系统发育和序列同源性分析将该病毒与玫瑰丛枝病毒、纤毛病毒2和无花果花叶病毒等一起置于纤毛病毒属内不同的“a亚组”分支上。对有症状和无症状树木进行的验证性RT-PCR分析表明，MaMaV可能是患病树木中引起症状的病毒。据我们所知，这是首次从枫树中描述纤毛病毒并对其进行完全的基因表征。随着MaMaV的发现，包含基因组差异很大的负义单链病毒的纤毛病毒属（直到最近一直被忽视）已大幅增加，包括22个已确定和假定的成员。
