Survey for major viruses in commercial Vitis vinifera wine grapes in Ontario

Abstract

BackgroundIn recent years, the Ontario grape and wine industry has experienced outbreaks of viral diseases across the province. Little is known about the prevalence of viruses and viral diseases in Ontario. Since 2015, we have conducted large-scale surveys for major viruses in commercial wine grapes in order to obtain a comprehensive understanding of the prevalence and severity of viral diseases in Ontario.MethodsA total of 657 composite leaf samples representing 3285 vines collected from 137 vine blocks of 33 vineyards from three appellations: Niagara Peninsula, Lake Erie North Shore and Prince Edward County. These samples covered six major red cultivars and five major white grape cultivars. Using a multiplex RT-PCR format, we tested these samples for 17 viruses including those involved in all major viral diseases of the grapevine, such as five grapevine leafroll-associated viruses (GLRaV-1, 2, 3, 4, 7), grapevine red blotch virus (GRBV), grapevine Pinot gris virus (GPGV), grapevine rupestris stem sitting-associated virus (GRSPaV), grapevine virus A (GVA), grapevine virus B (GVB), grapevine fleck virus (GFkV), arabis mosaic virus (ArMV), tomato ringspot virus (ToRSV), trapevine fanleaf virus (GFLV), among others.ResultsFourteen of the 17 viruses were detected from these samples and the predominant viruses are GRSPaV, GLRaV-3, GFkV, GPGV and GRBaV with an incidence of 84.0, 47.9, 21.8, 21.6 and 18.3%, respectively. As expected, mixed infections with multiple viruses are common. 95.6% of the samples included in the survey were infected with at least one virus; 67% of the samples with 2–4 viruses and 4.7% of the samples with 5–6 viruses. The major grape cultivars all tested positive for these major viruses. The results also suggested that the use of infected planting material may have been one of the chief factors responsible for the recent outbreaks of viral diseases across the province.ConclusionsThis is the first such comprehensive survey for grapevine viruses in Ontario and one of the most extensive surveys ever conducted in Canada. The recent outbreaks of viral diseases in Ontario vineyards were likely caused by GLRaV-3, GRBV and GPGV. Findings from this survey provides a baseline for the grape and wine industry in developing strategies for managing grapevine viral diseases in Ontario vineyards.

Characterization of grapevine leafroll-associated virus 3 genetic variants and application towards RT-qPCR assay design

“…The FPST assay yielded C T values ranging from 17.4 to 30 (mean of 21.2) from GLRaV-3-positive samples, with an high efficiency (110.91%), as calculated from the standard curve. In the few cases (18 samples) where high C T values (35.5 to 39.5) were detected (S5 Table), samples were re-tested by the FPST assay and end-point RT-PCR (for details about this assay see [29]), and confirmed to be negative. We hypothesize that this amplification was caused by cross-contamination.…”

A Diverse Virome of Leafroll-Infected Grapevine Unveiled by dsRNA Sequencing

“…Recently, Poojari et al conducted studies on the incidence of GLR and GRBV in BC [ 16 , 17 ] and surveyed for GLR, GFL, GRBV, Grapevine pinot gris virus (GPG) in NS vineyards in V. vinifera and Vitis interspecific hybrids [ 13 ]. In addition, GLR-3 and GRBV were observed in ON vineyards by Xiao et al [ 18 ] in a study aiming at improving methods to detect viruses for use in diagnostics. However, such studies have not been done in QC since 1996 [ 15 ], although concerns were raised by viticulturists as the industry expanded by more than 300% from 2003 to 2018, i.e., from 225 ha to 718 ha [ 19 , 20 ].…”

Somatic embryogenesis as a tool for virus elimination in Croatian indigenous grapevine cultivars

“…In Europe, the most damaging virus strains are listed in the classification of the European and Mediterranean Plant Protection Organization (EPPO 2019). The most widespread are Grapevine leafroll-associated virus 1, 2 and 3 (GLRaV-1, GLRaV-2 and GLRaV-3), Arabis mosaic virus (ArMV), Grapevine fleck virus (GFkV) and Grapevine fanleaf virus (GFLV) (Vončina et al 2017, Xiao et al 2018. According to the propositions of EPPO, certified virus-free vines should be free of these 5 viruses: ArMV, GFLV, GL-RaV-1, GLRaV-3 and GFkV (only rootstocks).…”