Advances in Protecting the Premier United States Grape Foundation Collection
Maher Al Rwahnih,* Teresa Erickson, Kristen
Farrar, Minsook Hwang, and Vicki Klaassen
*Foundation Plant Services, Department of Plant Pathology,
University of California, Davis, 455 Hopkins Rd., Davis, CA,
95616 (malrwahnih@ucdavis.edu)
Foundation Plant Services (FPS) is the primary source for certified, virus-tested, and true-to-variety grapevine plant material distributed to nurseries under the California Department of Agriculture’s Grapevine Registration and Certification (R&C) Program, which provides most grapevines planted in the United States. FPS has successfully maintained collections of grapes in open foundation vineyards on the UC Davis campus for >70 years. However, the Russell Ranch Foundation Vineyard (RRV) recently became infected with grapevine red blotch virus (GRBV), an economically significant insect-vectored grapevine virus that was introduced into RRV from outside sources. Due to the importance of this grape collection and the potential threat of insect-vectored viruses, FPS and the grape industry have determined the best course of action is to protect the core collection of grapevine selections in a foundation greenhouse to exclude both known and unknown vectors. With the tremendous support of the California grape industry, FPS has secured funding to initiate construction of the first of two greenhouses on-site at FPS in 2022. FPS plans to construct a second greenhouse adjacent to Greenhouse 1 in the future. The core grapevine collection will be re-registered and elevated to the RRV standards (Protocol 2010). All selections will be tested by high throughput sequencing (HTS)/polymerase chain reaction (PCR) using our rigorous, recently revised testing protocol, confirmed for trueness-to-type and, if needed, treated with microshoot tip therapy for virus elimination. The revised USDA-APHIS-PPQ- and CDFA-approved diagnostic testing protocol replaces biological indexing with a combination of HTS and PCR testing for release of plant material. These methods used in combination result in more accurate test results than biological indexing, which will ensure that grapevine selections maintained in the FPS Foundation Greenhouse are the highest-quality source of virus-tested grapevine stock for nurseries in CDFA’s Grapevine R&C Program.
Funding Support: California grape industry sources and Foundation Plant Services
