Elimination of Grapevine rupestris stem pitting-associated virus from Vitis vinifera 'Kyoho' by an antiviral agent combined with shoot tip culture

We evaluated the ability of different concentrations of Ribavirin (15 and 25 μg/mL, R15 and R25) to eliminate Grapevine rupestris stem pitting-associated virus (GRSPaV) from in vitro-cultured grapevine plants. Vitis vinifera 'Kyoho' plants infected by GRSPaV were used as the original plant materials. All of the plants survived in the treatment with R15 and R25 for 85 days, but all Ribavirin-treated plants exhibited phytotoxicity symptoms after 25 days. To ensure the accuracy of detection, optimal primer pair combinations (cpF1R2-cpF2R1 and rep1F1R2-rep1F2R1) were used to assess the eradication efficiency of GRSPaV from regenerated grapevine plants with a nested reverse transcription polymerase chain reaction. The results showed that the efficiency of the GRSPaV eradication was associated to virus titer of regenerated plant in different detection period. All surviving regenerated plants were tested for two rounds and the average elimination rates of GRSPaV in the two periods showed more different, 74.8% (113/151) and 52.3% (79/151), respectively. In addition, the efficiency of the GRSPaV eradication also depended on the concentrations and treatment duration of Ribavirin. The average elimination rates for the regenerated R25-treated and R15-treated plants in the second round detection were 54.1 and 50.6%, respectively. Moreover, the elimination rates for the R25-treated plants were 21.4, 37.5, and 77.8% after 45, 65, and 85 days of treatment, respectively. Combination of shoot tip culture with chemotherapy may greatly increase the efficiency of viral eradications.