PERSPECTIVE: The role of encapsulation in the development of plant cryopreservation techniques

Over the past 35 years, encapsulation technologies have played an important role in the development and diversification of cryopreservation techniques for cells and organized structures from numerous plant species. Encapsulation with calcium alginate was initially developed as a technological approach for the production of synthetic seeds. However, the coating of biological material with a hydrogel matrix subsequently promoted new applications that provided additional benefits to in vitro multiplication and preservation techniques. Alginate coatings can be complemented with growth regulators, antioxidants, and nanoparticles. These compounds have helped mitigate the toxic effects of cryoprotectants by regulating their penetration rate and have enabled the implementation of drastic desiccation treatments that would have otherwise been lethal. Furthermore, encapsulation facilitates the simultaneous handling of large quantities of samples, simplifying the ongoing handling required. Cryopreservation protocols based on encapsulation include Encapsulation-Dehydration, Encapsulation-Vitrification, V- and D-cryoplate methods. The objective of this review is to provide information on the impact of encapsulation of plant material on the advancement of cryogenic procedures and, consequently, on the understanding of tolerance of plant tissues to cryopreservation. In view of the advantages of encapsulation, it is considered that it will facilitate the long-term conservation of a greater number of plant species.