Metabolomic Effects and Genetic Diversity of Tobacco Ringspot Virus in Grapevines

Amber Loptien

doi:10.7273/000006327

Grapevine (Vitis vinifera) is an economically important crop grown worldwide to produce grapes that are used for a myriad of edible and marketable products. V. vinifera grapevines are susceptible to a wide range of biotic and abiotic stress factors that affect vine health and reduce fruit yield and quality. Among the many biotic stress factors affecting vineyards, grapevine fanleaf degeneration/decline caused by nematode-transmitted viruses, or nepoviruses, is one of the economically devastating viral diseases in grapevine-growing regions worldwide. Among the nepoviruses, Tobacco ringspot virus (TRSV, genus Nepovirus, family Secoviridae) is emerging as a significant constraint to vineyard health and production in Washington State vineyards. In this study, experiments were conducted for a better understanding of the impacts of TRSV in a wine grape cultivar (Vitis vinifera cv. Tempranillo). In the first part of the study, a High-Performance Liquid Chromatography (HPLC)-based approach was used to compare metabolomic profiles between virus-infected and healthy grapevines. Relative concentration of metabolite compounds (amino acids, carbohydrates, lipids, cofactors, nucleotides, peptides, hormones, secondary metabolites, and unnamed compounds) from berry and leaf samples collected at two phenological stages (pre- and post-veraison) were compared between symptomatic, TRSV-positive vines and non-symptomatic vines that tested negative for the virus. In the second part of the study, leaf samples were collected from TRSV-infected vinifera cultivars in a commercial vineyard and total RNA isolated from these samples was subjected to next-generation sequencing. Near complete sequences of RNA1 and RNA2 genomic segments were obtained from samples collected from 18 symptomatic vines from 6 viniferous cultivars (Syrah, Grenache, Tempranillo, Cabernet Franc, Cabernet Sauvignon, and Merlot). Nucleotide and amino acid sequences of the complete polyprotein open reading frame encoded individually by RNA1 and RNA2 segments were used to examine sequence identities among the 18 isolates from grapevines. Phylogenetic relationships of grapevine-infecting TRSV sequences available in GenBank to gain further insights into their evolutionary relationships. Overall results of this study will lead to a better understanding of metabolomic impacts and genetic diversity of TRSV in grapevines.

Metabolomic Effects and Genetic Diversity of Tobacco Ringspot Virus in Grapevines

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