2007 Annual Report 1a.Objectives (from AD-416) Determine effects of leaf roll disease in several Vitis vinifera L. cultivars on the following plant responses that are related to vineyard productivity and fruit quality: vegetative growth; fruit set; rates of net carbon exchange; fruit maturation; fruit quality at harvest; vine cold hardiness. 1b.Approach (from AD-416) Suspected virus-free and virus-infected vines from commercial vineyards will be selected. The virus-free Foundation Block at WSU-Prosser will be used to provide certified, virus-free vines as controls or benchmarks for the vines from commercial sites. Vegetative growth will be assessed from bud break until leaf senescence. Fruit productivity will be measured by several variables: number of clusters per vine and per shoot, percent fruit set, and berry weight. On fully expanded leaves of sentinel shoots, net photosynthesis and transpiration will be measured by infrared gas analysis. Berry samples will be collected to track ripening and fruit quality between véraison and harvest, using industry-standard indicator variables: berry weight, color, soluble solids, pH, and titratable acidity. Documents SCA with WSU. Formerly 5358-21000-025-11S (12/03). 3.Progress Report This report serves to document research conducted under a grant agreement between ARS and Washington State University. Additional details of research can be found in the report for the parent project 5358-21000-034-00D, Production Systems to Promote Yield and Quality of Grapes in the Pacific Northwest. Dr. Eastwell and collaborators conducted the following research towards the agreements objectives: Initial sequence determination of the RSPaV genome from our virus source, the table grape cultivar Volgo don, is approximately 80% complete and is on-going. This sequence information led to the production of the coat protein gene product used, in turn, to elicit the production of monoclonal antibodies. The availability of a serological assay for RSPaV will greatly enhance the ability of grape foundation and certification programs to monitor the occurrence of this virus. The production of antibodies is near completion, but validation of the assay to detect virus from diverse isolates remains. Extensive testing of grapevines was performed in an effort to determine baseline phytosanitary status of grapevines. This is the first time that the viroid status of grapevines has been examined in the Northwest. The data obtained from this process was a necessary prerequisite to selection of plant material used in this study. As a result of this indexing procedure, sources of ‘Okanagan Riesling’ and ‘Durif’ were identified that are free of all known viruses and GYSVd-1. Plants from these source vines were propagated from dormant cuttings and are the foundation of the pot culture trials to look at pathogen effects on horticultural traits. Additional propagated vines will be used in greenhouse studies to examine molecular interactions of the viruses and viroid. Bench-grafted vines of ‘Okanagan Riesling’ and ‘Durif’ on virus- and viroid-free rootstock ‘3309C’ were produced in preparation for the pot culture experiments. Grafted and self-rooted vines will be compared for characteristics of vine performance in the presence or absence of RSPaV. Vines to be used as the source of inoculum of each of the pathogens has been identified and propagated. Chip-budding from these vines onto virus-free test plants will be used to reliably create the requisite combinations of viruses and viroid in test plants. Establishment of the pot-grown vines outdoors will be completed during late summer of 2007. Inoculations of grapevines in these trials will be completed at that time by chip budding with material from identified single sources of infectious agents. A quantitative reverse transcription polymerase chain reaction (qRT-PCR) assay will be developed for RSPaV, GYSVd-1, and GLRaV-3. Currently, an end-point or nonquantitative RT-PCR based system is used in our program. Soule, M.J., Eastwell, K.C., & Rayapati, N.A. (2006). First report of Grapevine leafroll-associated virus-3 in American Vitis grapevines in Washington State. Plant Disease. 90:1461. ADODR Statement: The ADODR met with the cooperating PI and project personnel at meetings during the year and discussed results through phone calls, e-mail, and in person.