Cryopreservation of Potato Shoot Tips Using PVS3 Droplet-Vitrification

Efficient cryopreservation protocols ensuring high regrowth of shoot tips after rewarming are crucial for the secure long-term conservation of the more than 60,000 globally maintained potato accessions. At Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), over 2,150 accessions have been securely cryopreserved over the last 30 years. To ensure high regrowth potential and genetic stability after rewarming, the cryopreservation method was changed from dimethyl sulfoxide (DMSO) droplet freezing to plant vitrification solution 3 (PVS3) droplet vitrification and further improved and refined through key modifications. The last modifications included the adoption of microtubers for in vitro plant propagation, the preculture of in vitro plantlets and excised shoot tips in the dark, the direct cooling of PVS3-treated shoot tips and the rewarming using lower sugar concentration. As a result of these substantial improvements, the average regrowth potential of the complete secure cryo-collection has increased to 70%. However, further modifications and experiments will be conducted in future studies to ensure secure long-term conservation of the world's most important noncereal food crop.