8 The findings of this study were significant in that the factors responsible for spore germination by pressure were not identical to those responsible for spore superdormancy or nutrient germination. More interestingly, superdormant spores germinated normally at 150 MPa, which was surprising to the authors because spore germination induced at this level of pressure requires activation of the nutrient germinant receptors, and spore germination induced by this level of pressure is increased by prior heat activation. According to these authors, this result was expected since spore germination at this level of pressure does not require activation of nutrient germinant receptors. cereus that were not exposed to heat activation germinated normally, or similar to the rest of the spore population, at a pressure of 500 MPa. In a study by Wei et al., 8 superdormant spores of B. 46–48,51 Therefore it would be expected that superdormant spores, which have a decreased number of germinant receptors, would germinate poorly with low or moderate pressures. Since spore germination with moderate pressures is triggered by activation of nutrient receptors, spores with an increased number of germinant receptors will be more easily inactivated by moderate pressures. Hoover, in The Diverse Faces of Bacillus cereus, 2016 Superdormant Spores We conclude that comparative biology studies are urgently needed on the world's most threatened taxa so that conservation action can progress beyond species listing.Ĭryopreservation Orchids Storage characteristics Threatened species ex situ conservation.Sarah M. Moreover, we estimate that 60% of the listed species may require cryopreservation for long-term storage.

We found that whilst germination information is available for 28 species (23% of PSESP), storage characteristics are only known for 8% of PSESP (10 species). But what is known about the seed and spore biology (storage and germination) of at-risk species? We have used China's PSESP (the first group listing) as a case study to understand the gaps in knowledge on propagule biology of threatened plant species. Seed and spore germination in nature is a critical step in species regeneration and thus in situ conservation. Spore storage could provide a simple and economical method for fern ex situ conservation. Storing seeds is one of the main means of ex situ conservation for flowering plants.

Implementing conservation action for such listed species is urgent. In China, these most-at-risk species are described as 'plant species with extremely small populations' (PSESP). Of these, a significant number exist as populations of few individuals, with limited distribution ranges and under enormous pressure due to habitat destruction. Approximately one fifth of the world's plants are at risk of extinction.

Spore biology