Elimination of PDV from sweet cherry cultivars by in vitro chemotherapy

The aim of the present study was to determine whether chemotherapy with ribavirin can be used to eliminate Prune dwarf virus (PDV) from in vitro grown plants of infected sweet cherry cultivars ‘Tamara’ and ‘Amid’. Initial in vitro cultures were grown in Erlenmeyer flasks with 25 mL of MS medium (Murashige and Skoog, 1962), to which 1.5 mg L^‑1 BAP (6-benzylaminopurine) had been added. All cultures were cultivated in controlled environment chambers at 22±1°C. As soon as enough shoots were developed, individual shoots (5-10 mm in length) were excised from stock collections and transferred to treatment media with ribavirin. Ribavirin was added in concentration of 20 mg L^‑1 after autoclaving to the same MS medium as for multiplication. After a subculture period of 4 weeks, the apical part of the axis (about 3 mm in length comprising the apical meristem plus two-three primordial leaves) was dissected under a laminar flow hood and transferred to a fresh multiplication MS medium with 1.5 mg L^‑1 BAP for regeneration. The chemotherapy technique was able to eliminate PDV in high percentage according to the cultivar, ranging between 100.0 and 96.4% for cultivars ‘Tamara’ and ‘Amid’, respectively. In the course of chemotherapy cycles, ribavirin concentrations of 20 mg L^‑1, ‘Amid’ plants did not display symptoms of phytotoxicity and appeared vigorous and healthy. In contrary, 35% of ‘Tamara’ in vitro plants did not survive the ribavirin treatment. The obtained results demonstrate the effectiveness of the method to eliminate PDV by a combination of in vitro cultures, chemotherapy with ribavirin and subsequent removing of apical meristematic region.