How do we transport plant species with desiccation-sensitive germplasm in space?

Many useful plant species with potential for plant-based bioregenerative life support systems produce extremophile seeds with tolerance to multiple stressors, including desiccation, which allows for their transport through space in a dried state. However, other valuable species produce desiccation-sensitive seeds or are propagated clonally, and life sciences research in space has not yet addressed the challenge of alternative transport methods in microgravity for such material. Although liquid nitrogen storage is used on Earth for desiccation-sensitive germplasm, it poses atmospheric leakage problems to crewed spacecraft and therefore liquid nitrogen-free cryogenic freezing could be an alternative. Another promising approach is slow growth tissue culture, with subculture intervals extended to months or years through the precise control of the culture environment. Whilst the design of innovative systems for the transport of species with desiccation-sensitive germplasm will be demanding, the prospect still remains for their successful growth beyond Earth.