Format: ORAL

Jennifer K. Rowntree1, Neil Bell2, Jonathan Kendon3, Izadora Kervin1, Dave Lamacraft4, Silvia Pressel5

1 University of Plymouth, Plymouth, UK 2 Royal Botanic Garden Edinburgh, Edinburgh UK 3 Royal Botanic Gardens, Kew, Richmond, UK 4 Plantlife International, Salisbury, UK 5 Natural History Museum, London, UK

Between 2000-2016 a collection of UK threatened bryophytes was established at the Royal Botanic Gardens, Kew as part of the UKs conservation commitments. The majority of accessions were initiated from leafy gametophore material with dried and encapsulated protonemal material subsequently cryopreserved for long-term storage. Regeneration success rates after removing material from short-term cryo-storage were high, with all species able to regrow and 100% regeneration success for 50% of the species tested. However, viability after long-term storage remained unknown. In 2020 and 2021, after at least 14 years in the deep freeze, two species of ongoing conservation interest (Ditrichum cornubicumandOrthodontium gracile) were removed from the collection. Both successfully regenerated and were re-established into tissue culture, where they have been growing in protonemal form and producing leafy gametophores. Experiments are underway at the University of Plymouth to test weaning methodologies to enable growth in more natural environments. The impacts of long-term cryopreservation and the feasibility of using such material for reintroductions will be presented and discussed. The Kew collection contains over 20 species and the successful regeneration of two mosses is a hopeful sign that cryopreservation could be a useful tool for long term storage of bryophytes. This work forms part of a programme to develop standard methods for the reintroduction of bryophytes from cryopreserved collections and the removal and regeneration of additional species is planned.