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First Report of Grapevine virus T in Grapevine in Germany

Ruiz-García, A. B., Okic, A., Nourinejhad Zarghani, S., Olmos, A., Wetzel, T.
Plant disease 2018 v.102 no.8 pp. 1675
Arabis mosaic virus, Foveavirus, Hop stunt viroid, Vitis, coat proteins, computer software, cultivars, genes, high-throughput nucleotide sequencing, leaves, mixed infection, nucleotide sequences, nucleotides, plasmids, reverse transcriptase polymerase chain reaction, small interfering RNA, vineyards, viruses, Germany
Grapevine virus T (GVT) is a putative new member of the genus Foveavirus, family Betaflexiviridae, recently found to infect grapevine (Jo et al. 2017). In 2012, grapevine leaves from a Pinot Gris cultivar from the Rhineland-Palatinate area in Germany showing fanleaf-like symptoms were collected and analyzed by high-throughput sequencing of siRNAs using TrueSeq Illumina technology on a HiSeq 1000 system. Data analysis was performed using Geneious software and showed the presence of Arabis mosaic virus, grapevine rupestris stem pitting associated virus, and hop stunt viroid. Considering the great and continuous updating of the available viral sequences, a new analysis of the data mentioned above was performed in 2017. The BlastN and BlastX analysis of the 3,004 contigs assembled de novo by the Geneious software revealed the presence of 65 contigs between 47 and 227 nucleotides long related to GVT, with a nucleotide identity ranging between 81.5 and 93.8%. Mapping of the 7,485,280 Illumina reads using GVT isolate Cho (GenBank accession no. NC_035203) allowed the recovery of 94.6% of the viral sequence, scattered along the genome. To confirm the presence of GVT in German vineyards, primers were designed to specifically amplify by reverse-transcription polymerase chain reaction a fragment of 968 bp encompassing the coat protein (CP) gene, GVT-CP-F 5′-GTGAAAGGGGTGTGGTCCTC-3′ and GVT-CP-R 5′-CAGCGAACATTTGCCCTGTC-3′. A 968-bp fragment was successfully amplified, cloned into the plasmid pJET1.2, and sequenced (GenBank accession no. MG825613) from one of a total of 60 samples randomly collected from different grapevine-growing areas in Rhineland-Palatinate. BlastN analysis of the German isolate revealed 86% nucleotide sequence identity to the corresponding region of the GVT isolate Cho. To our knowledge, this is the first report of GVT in Germany. The incidence and relevance of GVT in German vineyards remain to be determined, because it was found in the latter case on an asymptomatic Riesling cultivar, while being found at first as a mixed infection on a symptomatic Pinot Gris cultivar.