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POSTERS: Population biology and genetics

Genetic Diversity of Grapevine leafroll-associated virus 3 in Washington State vineyards
Arunabha Mitra - Washington State University - Prosser. Sridhar Jarugula- Washington State University - Prosser, Rayapati Naidu- Washington State University, Emily Jordan- Chiawana High School, Bhanu Donda- SunBurst Plant Disease Clinic Inc.

Grapevine leafroll disease (GLD) continues to be a significant constraint to sustainability of the Washington State wine industry. Among the four grapevine leafroll-associated viruses (GLRaVs) documented in Washington vineyards, GLRaV-3 (genus Ampelovirus, family Closteroviridae) is the most insidious and widespread. A project was initiated to examine GLRaV-3 genetic diversity in vineyards to understand its epidemiology for implementing control strategies. A total of 1,260 samples were collected from red and white wine grape (Vitis vinifera) cultivars showing and/or suspected for GLD symptoms from thirteen vineyards. Samples were also collected from juice grape (V. labrusca) cultivars. Samples were tested for GLRaV-3 by RT-PCR using primers specific to a portion of the virus-encoded heat shock protein 70 homologue (Hsp70h) gene. The approximately 580 base pair amplicons generated from the Hsp70h gene were cloned and sequenced, and the derived virus sequences were aligned with corresponding sequences of GLRaV-3 isolates reported from different grapevine-growing regions worldwide. A global phylogenetic analysis of the Hsp70h sequences revealed the presence of five distinct variant groups differing from one another by 10-20% at the nucleotide level. GLRaV-3 isolates belonging to variant group I were found to be the most predominant. These results provide insights into the genetic makeup of GLRaV-3 for improved diagnosis of the virus and GLD management.