Preservation of the genome of Acer cappadocicum Gled. in cryopreservation

Background and objectives: Protecting genetic and ecosystem diversity is essential for breeding programs and the development of new cultivars. The preservation of biodiversity in the Hyrcanian forests, often regarded as a living fossil, is particularly crucial. Cryopreservation, which involves storing biological samples in tanks filled with liquid nitrogen (LN), is the most effective long-term preservation method for plant genetic resources. It serves as an alternative to seed or in vitro banks and can be applied to both vegetatively and generatively propagated crops. Extremely low temperatures stabilize cells in their current state, allowing for long-term storage. This method incurs significantly lower costs compared to classical preservation techniques, while also offering extended sample protection. Various parts of the plant—including seeds, organs, callus, differentiated cells, meristem, and pollen—can be stored using cryopreservation. This technique protects samples from pests and diseases while requiring minimal energy and space for storage. Additionally, it allows for the replication of samples at low cost and with minimal facilities under any environmental conditions. Cryopreservation enables the collection and storage of plant species from diverse climates in one location under uniform conditions. This study aims to evaluate the feasibility of storing Acer cappadocicum Gled. seeds under cryopreservation conditions.
Methodology: To store A. cappadocicum seeds in LN, they undergo various treatments to prevent the crystallization of free water and rupture of the plasma membrane at cryopreservation temperatures. The seeds were subjected to chemical treatments—30% glycerol and a vitrification solution—along with a physical treatment to reduce seed moisture using a desiccator containing silica gel. These treatments aimed to enhance tolerance to drought and cryogenic processes. After 24 hours in liquid nitrogen, the treated seeds, along with control seeds, were thawed immediately at 42 degrees Celsius. To break dormancy, all seeds—including treated seeds, control seeds that had been cryopreserved, and control seeds that had not been exposed to liquid nitrogen—were planted in moist sand at a temperature of four degrees Celsius. Germination began after three months, followed by assessments of viability and germination rates. Each treatment included three replications with 25 seeds per replication. Data analysis was conducted using one-way ANOVA within a completely randomized design, with means compared using Duncan's multiple range test.
Results: Among the cryopreservation treatments applied to the seeds, physical dehydration yielded the highest germination percentage (26%) and seed vigor index compared to other treatments. Conversely, treatments with 30% glycerol and vitrification reduced germination rates for A. cappadocicum, suggesting sensitivity to these cryopreservatives that may harm the seed embryo. A significant difference was observed in root length and root-to-stem ratio among treatments; however, no significant differences were found in seedling length or stem length at the five percent level.
Conclusion: In this research, seeds from three accessions of A. cappadocicum collected from different regions (Sari, Dehmian, and Kelich Kola) in Mazandaran province of Iran underwent physical dehydration treatment before being stored in LN tanks at the Research Institute of Forests and Rangelands in Tehran, Iran. This technology provides a viable method for conserving and protecting this species under critical conditions.