Effect of chemical and heat therapy on virus concentrations in <i>in vitro</i> potato plantlets

Abstract

Potato (Solanum tuberosum) plantlets were established in vitro to evaluate the effectiveness of chemicals and heat therapy for antiviral activity. Ribavirin was shown to be the most active chemical. Further studies were performed in which plantlets established from nodal cuttings were exposed to an alternating 4-h cycle of 35–31 °C and ribavirin (20 mg/L) therapy for 4 weeks, and then tested quantitatively for virus titer by the enzyme-linked immunosorbent assay. Plantlets were further propagated via nodal cuttings at room temperature without exposure to ribavirin. Virus assays were performed and virus-free plantlets were grown out as mature plants for a final virus assay. Ribavirin alone or in combination with heat therapy was effective in reducing potato virus M, S, and X titers (between 10- and 60-fold). Virus-free plants were obtained from both treatments. For potato viruses Y and leafroll, about a fourfold reduction in titer was observed after the ribavirin–heat treatments. When multiple viruses were present, quantitative (10- to 20-fold) reductions in potato viruses M, S, X, and leafroll were observed and resulted in plants free of potato viruses M, S, and X. This protocol enables the investigator to quantitatively monitor the impact of a single variable on the virus–host interaction. We have also been able to demonstrate that virus elimination can be obtained without a requisite meristem-tip excision step.