DETECTION AND ELIMINATION OF VIRUSES IN USDA HOP (HUMULUS LUPULUS) GERMPLASM COLLECTION
The United States Department of Agriculture (USDA), Agricultural Research Service (ARS) maintains a collection of Humulus germplasm at its National Clonal Germplasm Repository (NCGR) in Corvallis, Oregon, for the conservation and improvement of hop genetic resources. About 268 clonal accessions and seedlings are maintained as potted plants in a screen house. A core subset of 84 genotypes is also maintained in vitro under cold storage. Clonal accessions were tested by ELISA for Apple mosaic ilarvirus (ApMV), Arabis mosaic nepovirus (ArMV), Hop latent carlavirus (HpLV), American hop latent carlavirus (AHLV), Hop mosaic carlavirus (HpMV), and Prunus necrotic ringspot ilarvirus (PNRV). Ninety-eight hop clones out of 200 were found to be virus infected. HpMV was the virus most commonly detected (67% of infected plants), followed by HpLV (51%), AHLV (50%), and ApMV (28%). ArMV and PNRV were not detected. More than 60% of infected accessions contained 2 or more viruses, and more than 25% contained 3 or more. Cultivars Wye Target, Vojvodina, Shinsuwase, Cascade and USDA 21119 were infected with all 4 viruses. Alternating temperature heat-therapy and apical meristem culture were used to eliminate viruses from infected plants. Infected plants were grown for 2 weeks at temperatures alternating between 38°C and 30°C every 4 hours. Apical meristems 0.5mm or smaller were dissected and grown in vitro until large enough to transfer to soil in the glasshouse. Following a natural dormant period, plants were retested by ELISA. Of 182 plants regenerated from heat treated meristems, none tested positive in subsequent virus assays. Presently, the NCGR maintains 125 unique hop genotypes that have tested negative for all of these hop viruses.
Postman, J.D., DeNoma, J.S. and Reed, B.M. (2005). DETECTION AND ELIMINATION OF VIRUSES IN USDA HOP (HUMULUS LUPULUS) GERMPLASM COLLECTION. Acta Hortic. 668, 143-148
Humulus lupulus, virus detection, virus elimination, virus therapy, hop germplasm, apple mosaic, arabis mosaic, hop latent, American hop latent, hop mosaic, Prunus necrotic ringspot.