In vitro culture, cryopreservation, and field reintroduction of the endangered Mingan thistle

Current plant conservation efforts are hindered by, for example, poor seed germination, low viability, and insufficient propagation and preservation technologies. To address these problems, we devised an approach to plant conservation that integrates conservation, preservation, and restoration (CPR), which uses advanced in vitro techniques. We applied our method to the endangered plant species, Mingan thistle (Cirsium minganense Vict). We used micropropagation, embryo rescue, and cryopreservation, which together allowed germplasm banking, habitat restoration, and species recovery. Overcoming the natural dormancy and low viability of C. minganense seeds, embryo rescue achieved a remarkable 100% germination rate, highlighting its potential to bypass germination barriers. Optimal micropropagation protocols enhanced shoot proliferation and rooting and yielded vigorous plantlets with a nearly 100% survival during acclimatization. Cryopreservation protocols for in-vitro-grown shoot tips and seeds successfully preserved genetic diversity, which furthered immediate restoration efforts and long-term germplasm storage. Reintroductions of micropropagated and cryopreserved plants in the Mingan Archipelago National Park Reserve, Quebec, Canada, had high survival rates (average 90% after 2 years of transplant) and prolific flowering. Our results emphasize the importance of combining seed-based and in vitro propagation techniques to create genetically diverse and resilient plant populations and the value of cryobanking for ensuring germplasm availability under changing environmental conditions. The CPR strategy offers a scalable framework for conserving endangered plant species, safeguarding genetic diversity, and restoring ecosystems to support long-term biodiversity resilience.