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Ex situ conservation of bryophytes at the Royal Botanic Gardens, Kew.

 


Jenny Rowntree
Royal Botanic Gardens,
Kew,
Richmond,
Surrey TW9 3AB.

BACKGROUND

Conservation activities can involve in situ and ex situ components. Put simply, in situ conservation is the preservation of species within their natural habitats and ex situ conservation the preservation of species outside of that habitat. Historically, ex situ techniques have been widely and successfully used to conserve plants of commercial value, but have been under-used in the conservation of wild plants.

The importance and use of ex situ techniques in conservation has increased over the past decade, with the establishment of large projects such as the Millennium Seed Bank in the U.K. The increased use of ex situ techniques in conservation is thanks, in part, to their recognition in the Convention on Biodiversity (CBD), which was signed and ratified by the U.K. in the early 1990s. More recently, the Global Strategy for Plant Conservation contains specific targets for the ex situ conservation of threatened species.

Typical ex situ techniques might involve the creation of living collections (either in soil or tissue culture), or long-term storage collections (e.g. seed or spore banks, or in liquid nitrogen as a bank of cryopreserved material).

A project for the ex situ conservation of endangered U.K. bryophytes was launched in August 2000, at the Royal Botanic Gardens, Kew with the appointment of a dedicated bryophyte conservation officer. The initial project ran for three years and concentrated on the development of standard methods for the collection, sterilisation, tissue culture and cryopreservation of bryophytic material. Funding for the work was extended for a further three years in December 2003 and the current emphasis of the work is to expand the living and cryopreserved bryophyte collections. Methods for the introduction of specific species into their natural environments are also under development.

The project is a collaboration between the Royal Botanic Gardens , Kew and the UK statutory conservation agencies (English Nature, Scottish Natural Heritage, Countryside Council for Wales ). There is an emphasis on developing ex situ techniques as a complement to, and not a replacement for, in situ conservation efforts.

COLLECTION OF MATERIAL

Collection of material for the project is only undertaken by authorised individuals and after consultation with the appropriate conservation agency and/or biodiversity action plan lead partners. Three protocols have been produced and circulated for the collection of a) desiccation tolerant mosses, b) desiccation intolerant mosses and leafy liverworts and c) thalloid liverworts and hornworts. The protocols emphasise the importance of limiting detrimental effects to the in situ populations and collecting representative genetic samples. Where possible the collection of sporophytes is preferred, but protocols have also been developed for the sterilisation and production of protonema from gametophores, thalli and gemmae alone.

INITIATION INTO CULTURE

Bryophytes from the ex situ collection growing in Petri dishes in axenic culture.

Bryophytes are grown in axenic culture (without fungal, algal and bacterial contaminants) in the ex situ collection. Although artificial, axenic culture provides a more uniform and secure method of maintaining plants in a tissue culture collection. Axenic culture is also an advantage if plants are to be stored long-term in liquid nitrogen (cryopreserved) as they can be readily overwhelmed by contaminants during recovery. In addition, material guaranteed contaminant-free is easier to transport across international borders, and has advantages over non-axenic material for use in some genetic analyses.

Sterilisation protocols have been developed for a) sporophytes, b) leafy gametophores, c) gemmae and d) thallus tissue using the sterilising agent Sodium dichloroisocyanurate and without the addition of detergents.

CRYOPRESERVATION

For long-term storage the bryophytes are cryopreserved in liquid nitrogen

The ex situ project aims to provide long-term basal storage of rare bryophyte material for use in future conservation programmes. Material that is continually sub-cultured (as is necessary to maintain a tissue culture collection) is likely to become adapted to growing in culture conditions over time and thereby lose genetic diversity. This is particularly problematic for material retained for conservation purposes where reintroduction is a possible long-term objective. Cryopreservation is the storage of living material at -196 oC in liquid nitrogen and has been used successfully for the long-term storage of many different plants. Cryopreserved material is held in a state of suspended animation and therefore does not become adapted to growing in culture. A standard protocol has been developed for the cryopreservation and recovery of protonemal material and protocols are under development for leafy gametophores.

FUTURE WORK

The ex situ collection is continually expanding (see Table for current species held) to incorporate more rare bryophyte species. Material is systematically being cryopreserved and the development of cryopreservation methods is ongoing. Trials are also underway to investigate methods for the introduction of bryophytic material from the collection into a more natural environment.

Moss protonema weaned onto a rock substratum.

Species

(Blockeel & Long, 1998)

Status

World Red List

(IUCN, 2000)

European Red List

(ECCB, 1995)

British Red List

(Church et al., 2001)

Aplodon wormskjoldii (Hornem.) Kindb.

Axenic

Cryo

 

 

Critically Endangered

Bartramia stricta Brid.

Axenic

Cryo

 

 

Critically Endangered

Cyclodictyon laetevirens Mitt.

Axenic

Cryo

 

Rare

Endangered

Ditrichum cornubicum Paton

Axenic

Cryo

Critically Endangered

Endangered

Endangered

Ditrichum plumbicola Crundw.

Axenic

Cryo

 

Vulnerable

Near threatened

Jamesoniella undulifolia (Nees) Müll. Frib.

Non-Axenic

Vulnerable

Endangered

Endangered

Leptodontium gemmascens (Mitt. Ex Hunt) Braithw.

Axenic

Cryo

 

Rare

Vulnerable

Micromitrium tenerum (Bruch & Schimp.) Crosby

Axenic

Cryo

 

Vulnerable

Critically Endangered

Orthodontium gracile Schwägr. ex Bruch, Schimp. & W. Gümbel

Axenic

Cryo

 

Endangered

Vulnerable

Orthotrichum obtusifolium Brid.

Non-Axenic

 

 

Endangered

Orthotrichum pallens Bruch ex Brid.

Axenic

Cryo

 

 

Endangered

Rhynchostegium rotundifolium ( Brid.) Bruch, Schimp. & W. Gümbel

Axenic

 

 

Critically Endangered

Seligeria carnicolica (Breidl. & Beck) Nyholm

Axenic

 

 

Critically Endangered

Tortula cernua (Huebener) Lindb.

Axenic

 

 

Endangered

Weissia multicapsularis (Sm.) Mitt.

Axenic

Cryo

 

Endangered

Endangered

Weissia rostellata (Brid.) Lindb

Axenic

Cryo

 

Rare

Near threatened

Zygodon forsteri (Dicks.) Mitt.

Axenic

 

Vulnerable

Endangered

Zygodon gracilis Wilson

Axenic

 

Vulnerable

Endangered

BIBLIOGRAPHY

BLOCKEEL, T. L. & D. G. LONG. (1998) A check-list and census catalogue of British and Irish bryophytes. Cardiff, U.K.: British Bryological Society.

CHURCH, J. M., N. G. HODGETTS, C. D. PRESTON & N. F. STEWART.(2001) British red data books - mosses and liverworts. JNCC, Peterborough.

ECCB.(1995) Red data book of European bryophytes. European Committee for the Conservation of Bryophytes, Trondheim.

IUCN.(2000)The 2000 IUCN World Red List of Bryophytes. IUCN SSC bryophyte specialist group.

 

 
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