Grapevine red blotch virus: Absence in Swiss Vineyards and Analysis of Potential Detrimental Effect on Viticultural Performance

Abstract

Grapevine red blotch virus (GRBV) is a recently described virus that infects grapevine. Little information is available on the possible occurrence and distribution outside North America. Therefore, we surveyed commercial vineyards from the three major grape-growing regions in Switzerland to determine the presence or absence of GRBV. In total, 3,062 vines were analyzed by polymerase chain reaction. None of the vines tested positive for GRBV, suggesting the absence of GRBV from Swiss vineyards. We also investigated whether GRBV was present in 653 grapevine accessions in the Agroscope grapevine virus collection at Nyon, including dominantly Swiss (457) but also international accessions. Only six referential accessions were infected by GRBV, all originating from the United States, whereas all others from 10 European and 8 non-European origins tested negative. High-throughput sequencing analysis of Zinfandel A2V13, in the collection since 1985, confirmed close similarity of GRBV isolate Z_A2V13 to American isolates according to genomes deposited in GenBank. Because the Zinfandel A2V13 reference was also maintained grafted on the leafroll virus indicator Vitis vinifera ‘Gamay’, we evaluated the effect of GRBV on viticultural performance over a 3-year period. Our results showed clear detrimental effects of GRBV on grapevine physiology (vine vigor, leaf chlorophyll content, and gas exchange) and fruit quality. These findings underscore the importance of implementation of GRBV testing worldwide in certification and quarantine programs to prevent the dissemination of this virus.

Absolute Quantification of Grapevine Red Blotch Virus in Grapevine Leaf and Petiole Tissues by Proteomics

“…Furthermore, we could confirm the presence of the GRSPaV by way of its 28 kDa coat protein in GRBV-free and infected plants at similar expression levels, confirming RT-PCR results produced at Agroscope ( Reynard et al, 2018a ).…”

“…We could identify the V1 and V2 GRBV proteins in petioles of GRBV-infected plants but not in the leaves. V1 and V2 were the only GRBV proteins identified from the six possible open-reading frames of the GRBV genome as deposited in the NCBI GenBank database with accession number MF276895 ( Reynard et al, 2018a ). We achieved sequence coverages of 75.0% for the V1 (amino acid range of 33–324) and 53.8% for V2 (range 60–165) by combining the shotgun and in-gel results (Figure 6 ).…”

“…Carbamidomethylation on cysteine was set as a fixed modification, methionine oxidation and protein N-terminal acetylation as variable modifications. The fragment spectra were interpreted with the Andromeda search engine against a forward and reversed protein sequence database containing all Vitis vinifera entries deposited at UniprotKB (version 2016_08), including other species with a V. vinifera association, and supplemented with the potential open-reading frames from GRBV (accession MF276895) and GRSPaV as sequenced at Agroscope ( Reynard et al, 2018a ), totaling in 65,423 proteins. Peptide spectrum matches and protein identifications were accepted at a 1% false discovery rate (FDR) and requiring at least two unique or razor peptides per protein group identification.…”

“…A very recent study discovered a reprogramming of the post-transcriptional machinery and abnormal transcription factor expression causing the attenuation of the normal berry ripening process ( Blanco-Ulate et al, 2017 ). GRBV is widespread in North America ( Krenz et al, 2014 ) while Europe seems to be GRBV free ( Reynard et al, 2018a ). There is evidence that wild grape is a carrier of GRBV and that it is transmitted by a treehopper Spissistilus festinus ( Bahder et al, 2016 ; Perry et al, 2016 ).…”

Water Deficits Do Not Improve Fruit Quality in Grapevine Red Blotch Virus-Infected Grapevines (Vitis vinifera L.)

“…There was no response of any of the vegetative growth variables to virus status in either year, with only a small effect of irrigation treatment on pruning mass in 2018-likely due to the larger differences in vine water status that year. Recently, Martıńez-Lüscher et al (2019) showed no GRBD effect on vine pruning mass in Cabernet Sauvignon, while Reynard et al (2018) reported pruning mass reductions of 33-35% in Gamay. Considering that leaf gas exchange was not reduced in GRBV+ vines preveraison in this study and in Martıńez-Lüscher et al (2019), and that most shoot elongation and canopy development occurs during this time (Matthews et al, 1987), it seems unlikely that GRBV infection would negatively impact vegetative growth unless there were other confounding biotic or abiotic factors.…”