1a.Objectives (from AD-416)
Conduct genetic diversity studies among economically important grapevine viruses documented in the Pacific Northwest region.
1b.Approach (from AD-416)
It is imperative that molecular diversity studies be completed for the major viruses in the PNW region to improve our understanding of the spectrum of their variability for the development of improved diagnostic tools in order to be able to detect all the strains of a given virus and prevent their spread in PNW vineyards. Towards this goal, we will initially focus molecular diversity studies on GLRaV-2, GVA, GVB, GRSPaV, GFLV and ToRSV. We will extend these studies to other GLRaVs during the course of this project, if there is an indication of molecular variability among these viruses. Documents grant with Washington State University.
The perennial nature of grapevines, lack of selection pressure due to their clonal propagation and multiple infections over the years can result in building up of a mixture of several viruses and their sequence variants within a single infected grapevine. Analyzing the spectrum of viruses and their variants from different grapevine cultivars will improve our understanding of the sanitary status of vineyards and provide information for the development of better diagnostic tools and sound management practices that will lead to reduced spread and economic impact of several debilitating viruses and their variants. Using molecular biology approaches, we have documented the presence of genetically distinct variants of Grapevine leafroll-associated virus 2 (GLRaV-2), Grapevine rupestris stem pitting-associated virus (GRSPaV) and Grapevine fanleaf virus (GFLV) in the Pacific Northwest (PNW) as a consequence of introduction and subsequent dissemination of infected grapevine cuttings. A detailed assessment of the molecular diversity of field isolates of GLRaV-2, GRSPaV and GFLV in the region provided a foundation for evaluating their role in the epidemiology of grapevine leafroll, rugose wood and fanleaf diseases, respectively, and developing strategies to contain their spread. From a practical point of view, the knowledge and resources generated in this study will offer improved capacity for the detection and discrimination of a broad range of virus variants that might escape antibody detection in clean plant programs. The project outputs have been incorporated in ‘clean’ plant programs and disseminated to various stakeholders through extension and outreach programs for increased awareness of viruses and their impacts on sustainability of the wine grape industry in the region.
Methods of ADODR monitoring included meetings, site visits, phone calls and e-mail.