Cryobiotechnology of Korean Orchid Biodiversity: A Case Study Using Cymbidium kanran

Abstract

Orchids are exceptionally vulnerable to climatic changes and destruction of natural habitats. Many orchid species become extinct at both national and global levels, and their conservation is a matter of critical importance. In vitro and cryobiotechnology approaches are effectively used to establish medium-term and long-term collections of threatened orchid species. In this study, the feasibility of droplet vitrification and preculture desiccation methods for cryopreservation of the Korean orchid Cymbidium kanran was tested using sections, lateral buds and apical tips excised from in vitro grown rhizomes. Preculture with 0.5–1.0 mg/l ABA for 10–21 days followed by treatment in a liquid medium with gradually increasing sucrose concentration enhanced tolerance of rhizome sections and buds to both vitrification solutions and desiccation. Droplet vitrification of rhizome buds and sections using PVS2, PVS3 or alternative vitrification solution A3 was not feasible under conditions tested in the study. High regrowth (86– 90%) of rhizome sections after cryopreservation was achieved following the combination of ABA-and-sucrose preculture with desiccation over silica-gel to water content below 34%. This study opens the door for the development and optimization of cryopreservation methods for endangered terrestrial Asian orchids that are usually difficult to propagate and conserve ex situ.