A practical framework for the cryopreservation of palm species

Palms ( Arecaceae ) contribute remarkable economic and environmental values to human life. However, many elite and commercial palm species are becoming critically endangered and demand immediate action to preserve their genetic resources. Cryopreservation has established itself as the definitive in vitro conservation method for recalcitrant-seeded species, such as those within the Arecaceae . Progress in this area has moved steadily forward over the last three decades with the development of various techniques for different explants and palm genotypes and for molecular testing methods to ensure genetic fidelity is maintained in the regenerants. There remains a key challenge to properly identify the components that will enable the long-term conservation of palms using cryopreservation. This review methodically analyzes the state-of-the-art cryopreservation techniques developed for palms and places them within a practical framework. This framework encompasses four underlying components, namely the tissue culture approaches required, the recalcitrant nature of the palm seed, the cryobiology and cryogenic techniques required, and fidelity assessment after cryopreservation. Through a critical analysis of this framework, further optimization of palm cryopreservation protocols and more fundamental studies on the physiological and molecular changes in cryopreserved palm tissues are recommended. The present review helps to showcase a multi-decade global attempt to preserve these mostly recalcitrant species through ex situ collections. From a conservationist’s perspective, this review hopes to stimulate awareness for further concerted efforts in the conservation of rare and endangered plant families. Meanwhile, from a managerial perspective, this work serves to inform decision-makers of the global research effort underway to improve key components of the cryopreservation program for palm species and to encourage funding bodies to appropriately allocate resources to these much-needed research areas.