Improvement to the D Cryo-plate Protocol Applied to Practical Cryopreservation of In Vitro Grown Potato Shoot Tips

We modified the D cryo-plate protocol by paper mounting to the cryo-plate with alginate gel and shoot tips, and cryopreserved shoot tips of 13 potato genotypes (potato genetic resources in Mexico) using the revised and optimized D cryo-plate protocol. There were no significant differences in regrowth of cryopreserved shoot tips by addition of the paper mounting step to the base D cryo-plate protocol, besides a reduction in dropping shoot tips in steps during the whole procedure. Some steps of revised D cryo-plate protocol were optimized or reconfirmed, and the effect of optimizations such as cold-hardening, loading solution treatment, and post-rewarming treatment on the regeneration of shoot tips was studied. This optimized protocol was successfully applied to 'B-71-240-2' and 12 additional potato genotypes, resulting in 70.0%-93.3% regrowth with an average of 82.8% and stable storage for 1 year. When introducing new cryopreservation techniques, modification and optimization of the method are required to adjust to each laboratory's circumstances. This optimized D cryo-plate method will facilitate cryobanking of potato and other plant genetic resources in Mexico for long-term preservation in a genebank.