Cryostorage of the threatened and endemic Moehringia jankae griseb. ex Janka through droplet-vitrification and encapsulation-dehydration

Abstract The threatened and European-endemic species Moehringia jankae Griseb. ex Janka (Caryophyllaceae) exhibits a critically restricted natural distribution confined solely to the Western Black Sea region. Facing intense adaptive challenges imposed by progressive climate change and increasing anthropogenic disturbances, we assert that cryopreservation constitutes the only feasible and sustainable long-term ex situ conservation strategy for this species. Consequently, the present investigation optimized droplet-vitrification and encapsulation-dehydration methodologies designed to ensure the secure preservation of M. jankae , concurrently upholding robust regrowth rates of explants post-liquid nitrogen immersion. Our findings demonstrate maximal regrowth efficiencies: 83% via droplet-vitrification following a 24-hour osmoprotection in 0.5 M sucrose, succeeded by 15 min of PVS2 dehydration; and 85% through encapsulation-dehydration after a 24-hour osmoprotection in 0.75 M sucrose, and 23% moisture content of alginate beads. These biotechnological approaches demonstrate significant utility for the effective ex situ conservation of additional rare or endangered plant species, thereby securing the long-term protection of global biodiversity. To the best of our knowledge, this study represents the first comprehensive documentation of M. jankae cryopreservation, thereby establishing critical cryopreservation protocols (droplet vitrification and encapsulation-dehydration) essential for the ex situ conservation of this unique species.