Cryobiotechnologies: Tools for expanding long-term ex situ conservation to all plant species

In the face of habitat loss and a changing climate, there is a growing need for increased efforts to conserve plant biodiversity. The genetic diversity of many crops is well represented in ex situ seed banks and the number of seed collections of wild species is growing. However, approaches beyond conventional seed banking are needed for some species. Cryobiotechnology, including cryopreservation (i.e. ultra-cold temperature) and the in vitro technologies that support it, offers the potential for conserving these species, securing germplasm for future restoration of species that are declining in the wild. Cryopreservation has been demonstrated as a safe and effective method for conserving desiccation tolerant short-lived seeds, zygotic embryos, dormant buds, spores, pollen, shoot tips, somatic embryos, gametophytes, and algae, with a growing number of studies indicating that viability can be maintained over at least 2–3 decades, including a recent study in this laboratory. Instituting the use of long-term cryopreservation on a broad scale, supported by in vitro technologies, is of immediate importance to stem the loss of species diversity, and this can be accomplished by building on the expertise and infrastructure that has developed over the past 30 years. Here we review the application of cryobiotechnologies to a variety of plant tissues in order to highlight their potential and to call for a global effort to broaden ex situ conservation beyond conventional seed banking. •There is a need for methods beyond seed banking for ex situ plant conservation.•Cryobiotechnology offers options for long-term storage of a variety of plant tissues.•Survival in liquid nitrogen over 2–3 decades has been shown for many plant tissues.•Investment into its widespread use is needed to prevent future species loss.