Meristem Tip Culturing For The Elimination Of Grapevine Viruses

The new grapevine importation and quarantine facility at FPMS has begun accepting orders this winter. When the next step is the construction is complete, grapevine virus elimination services can be added to the program. The most important technical problem which limits the importation of winegrape clones and rootstocks is the difficulty with which grapevine viruses are eliminated using the old heat therapy techniques. These techniques are slow and inefficient. A number of laboratories worldwide have reported that meristem tip culturing is an effective technique for eliminating grapevine viruses. We have developed those -feke&e techniques in our laboratories and are evaluating their effectiveness. This approach should result in streamlining of procedures for the elimination of grapevine viruses from valuable grape propagating materials. As a result of these streamlined procedures, the length of time required for entry of infected materials should be substantially reduced. In turn, this should provide greater accessibility to foreign materials which include European wine clones, improved rootstocks which are needed for many reasons including their potential phylloxera resistance and other products of worldwide grapevine breeding programs. Furthermore, these techniques should further the efficient therapy for virus elimination of important California field selections suspected or proven to be infected with grapevine latent viruses. With the increased funding available during the 1992-1993 research year it was possible to hire a technician trained in tissue culture research on other crops for this project. This has allowed us to recapture the momentum which was lost in the 1991-1992 cycle when only part-time student help was available for the work. Many of the objectives of this project have been accomplished. In the cases where the work is complete or nearly complete, I have attached the scientific papers which document the research. Some of these manuscripts are not completed in which case the prospects for finishing the projects is discussed in the corresponding appendix. The technique of shoot tip culture seems to be sucsessful. Treated explants will be monitored to insure that virus does not reappear. Additional future work will focus on improving survival rates and efficiency.