Cryobanking of Korean allium germplasm collections: results from a 10 year experience

This paper reviews a 10-year experience in establishing a cryopreserved Allium germplasm collection at the genebank of the National Agrobiodiversity Center, Republic of Korea. A systematic approach to Allium cryopreservation included: 1. revealing the most critical factors that affected regeneration after cryostorage; 2. understanding the mechanisms of cryoprotection by analyzing the thermal behavior of explants and cryoprotectant solutions using DSC and influx/efflux of cryoprotectants using HPLC; 3. assessing genetic stability of regenerants; and 4. revealing the efficiency of cryotherapy. Bulbil primordia, i.e. asexual bulbs formed on unripe inflorescences, proved to be the most suitable material for conservation of bolting varieties due to high post-cryopreservation regrowth and lower microbial infection level, followed by apical shoot apices from single bulbs and cloves. A total of 1,158 accessions of garlic as well as some Allium species have been cryopreserved during 2005-2010 using the droplet-vitrification technique with a mean regeneration percentage of 65.9 percent after cryostorage. These results open the door for large-scale implementation of cryostorage and for simplifying international exchange for clonal Allium germplasm.