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POSTERS: Population biology and genetics

The Incidence of Grapevine Viruses in Four Texas Blanc du Bois Vineyards
David Appel - Texas A&M University. Frances Pontasch- Texas A&M University, Maher Al Rwahnih- University of California-Davis, Sheila McBride- Texas A&M University, Olufemi Alabi- Texas AgriLife Research and Extension Center

Winegrape production in Texas continues to increase to support a ten-fold increase in wine production over the past two decades. Viruses are one of the most serious threats to grape quality throughout the world’s major winegrape regions. Blanc du Bois (BdB), a white grape American hybrid bred for Pierce’s Disease resistance, comprises the 5th most planted winegrape variety in Texas. Because of an unexplained curling and deformation of BdB foliage, a systematic sampling of four Blanc du Bois vineyard blocks in the Texas gulf coast region was conducted in May 2018. An average of 50 vines per block were sampled, pooled and subsequently processed for high-throughput sequencing (HTS) to determine the virome and potential role in symptom development, vine health and grape quality. Grapevine leafroll-associated virus 3 was the most prevalent virus ranging from 0% to 63% incidence in the four vineyards. The next most prevalent virus was Grapevine red blotch virus, found only in one vineyard at 71% incidence. Other notable viruses of lesser incidence were Grapevine fleck virus, Grapevine virus B, Grapevine virus E, and grapevine virus M (GVM). GVM has only been recently described as a new Vitivirus species. These results have confirmed the presence of a complex virome in Texas vineyards. Further studies are underway to gain a better understanding of their impact.