Cryopreservation strategies for trees: Leveraging organogenesis and somatic embryogenesis for effective conservation

Trees are fundamental to ecosystems, supporting biodiversity, regulating climate, storing carbon and providing vital resources. Several species are under severe threat from deforestation, habitat destruction, urban expansion and climate change, endangering both the species and the ecosystem services they provide. Traditional conservation methods, such as seed genebanks and field genebanks, face challenges like genetic degradation and high maintenance costs. Cryopreservation offers a promising alternative, preserving genetic material at ultra-low temperatures, halting biological processes and minimizing storage space needs. This method is especially effective for species with recalcitrant seeds or difficulty in propagation. Integrating techniques like somatic embryogenesis and organogenesis further enhances cryopreservation. Somatic embryogenesis enables the development of embryos from somatic cells, facilitating the regeneration of trees from cryopreserved tissues. Similarly, organogenesis promotes the development of in vitro cultures for species that are otherwise challenging to conserve, allowing for cryopreservation of in vitro explants. The combination of these techniques not only preserves genetic material but also ensures the regeneration of viable plants, providing a comprehensive approach to tree conservation. This review highlights the critical role of cryopreservation in preserving tree diversity, with a focus on somatic embryogenesis and organogenesis, exploring current practices, challenges and future directions.