First Report of Grapevine leafroll-associated virus-9 in Washington State Vineyards

Area of Science:

• Plant Pathology
• Virology
• Viticulture

Background:

• Grapevine leafroll disease (GLD) significantly impacts wine grape production.
• Nine Grapevine leafroll-associated viruses (GLRaVs) are known to cause GLD.
• GLRaV-1, -2, and -3 were previously identified in Washington State grapevines.

Purpose of the Study:

• To investigate the presence of other GLRaVs in Washington grapevines exhibiting GLD symptoms.
• To specifically detect and confirm Grapevine leafroll-associated virus-9 (GLRaV-9) in symptomatic grapevines.

Main Methods:

• Leaf samples were collected from symptomatic red-berried grapevine cultivars across 19 vineyards.
• Reverse transcription-polymerase chain reaction (RT-PCR) was employed using primers specific for the GLRaV-9 HSP-70h gene.
• Positive RT-PCR products were confirmed through sequencing of cloned amplicons from the HSP-70h and coat protein (CP) genes.

Main Results:

• GLRaV-9 was detected in 14 samples from 5 cultivars (Cabernet Sauvignon, Merlot, Pinot Noir, Mourvedre, and Lagrein).
• Sequencing confirmed high nucleotide (94-100%) and amino acid (96-100%) identity with known GLRaV-9 sequences.
• This study provides the first evidence of GLRaV-9 occurrence in Washington State vineyards.

Conclusions:

• GLRaV-9 is present in Washington State wine grape cultivars, expanding its known distribution.
• The findings indicate a wide distribution of GLRaV-9 across various Vitis vinifera cultivars.
• Further research is needed to determine the economic impact of GLRaV-9 on wine grape production.