Meristem tip culturing for the elimination of grapevine viruses

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 those techniques in our laboratories and are evaluated their effectiveness. This technology 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. This will be the final report on this project. Nearly all 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. My laboratory will be completing the final experiments in the next few months to fill in the last of the data needed for publication. Treated explants will be monitored to insure that virus does not reappear. Additional future work will focus on improving survival rates and efficiency. The technique of shoot tip culture seems to be successful. Foundation Plant Materials Service is now using this technique to perform therapy on both diseased vines from quarantine and on valuable California field selections which are not available as certified stock.