Investigating Cryotherapy as a Novel Approach to Virus Elimination in Orchids

Abstract

High quality orchids are important for Hawaii’s floriculture industry and a barrier to their production is viral infection, primarily from Cymbidium mosaic virus (CymMV) and Odontoglossum ringspot virus (ORSV). Prevention and elimination techniques, including virus screening, thermotherapy, and chemotherapy, exist as solutions. Each approach offers varying levels of success; it is easier to eliminate CymMV than ORSV due to differential movement in orchids. Cryotherapy is a new approach to virus elimination in crops and ornamentals, using liquid nitrogen submergence of explants to burst virus-infected cells while preserving undifferentiated cells with cryo solutions. Vitrification and Droplet-vitrification methods were assessed to determine explant regeneration success. From this a modified Droplet-vitrification protocol was created for cryotherapy studies involving Dendrobium and Miltassia (CymMVinfected) and Oncidium (ORSV-infected). ORSV was not eliminated in the two regenerated explants following the protocol presented here. CymMV-infected explants failed to regenerate and could not be assessed for virus elimination.