Abstract This study presents the first reproducible vitrification-based cryopreservation protocol for shoot tips of sycamore maple ( Acer pseudoplatanus L.), a tree of high ecological and economic significance in Central Europe. By safeguarding genetically verified material, including rare wood traits, this work supports the integration of the species into long-term ex situ conservation programmes. We investigated the influence of explant size, hardening duration, daytime temperature during hardening, and pre-culture across four genotypes. The protocol involved 4 wk of cold hardening under short-day conditions, a pre-culture at low temperature, vitrification with a plant vitrification solution, storage in liquid nitrogen, rapid rewarming, and gradual recovery under controlled light. Explant size proved decisive: shoot tips of 1–2 mm in length regrew at substantially higher rates and developed more vigorous shoots than larger explants. Four weeks of hardening with daytime temperatures between 3 and 7°C followed by pre-culture at 5°C produced the most reliable outcomes. The most responsive genotype reached regrowth in up to 90% of the explants, and for the remaining three genotypes, 50–64% regrowth was achieved. Post-cryopreservation, multiplication factors were comparable to non-cryopreserved control. Hyperhydricity occurred in a genotype-dependent manner but remained low overall. Thus, the protocol enables cryopreservation of sycamore maple genotypes, ensuring both survival and propagation potential.
Karfik et al. (2026) studied this question.