Establishment of meristem culture for virus-free and genetically stable production of the endangered plant Hosta capitata

Hosta species endemic to Korea are currently suffering from infection with Hosta virus X (HVX), and it has been difficult to produce virus-free plants when using infected plants as a source of material for in vitro and vegetative propagation in continuous production processes. Genetic variation in in vitro-regenerated plants has also been detected in some Hosta cultivars. Therefore, we aimed to develop an in vitro propagation method for the production of virus-free and genetically stable plants. First, we collected Hosta capitata showing symptoms of viral infection and confirmed the presence of an HVX virus gene using reverse transcription (RT)–PCR, followed by optimization of the sterilization of in vivo bulbs. Meristems derived from sterilized bulbs were cultured in media containing different concentrations of 1-naphthaleneacetic acid (NAA) with either benzyl aminopurine (BA) or thidiazuron (TDZ). The combination of 0.1 mg/l NAA and 3.0 mg/l BA generated the highest number of shoots per explant, and these shoots had a higher fresh weight. The addition of nano-silver (NAg) particles to the regeneration medium distinctly stimulated plant growth. According to the results of RAPD analysis, the meristem-derived plants were genetically stable compared with donor plants grown in a greenhouse, and absence of the HVX gene was also observed, indicating freedom from HVX infection. Therefore, they would be highly valuable for use in the landscape industry. We expect that the method proposed in this study will also prove helpful for generating virus-free, genetically stable plants in the commercial production of other Hosta species.