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Freezing Ascension's rare ferns for the future

Ed Jones
25 August 2011
Blog team: 
Ed Jones has just spent a year working with Kew's Conservation Biotechnology team investigating different methods of conserving several of the threatened ferns unique to Ascension Island in the South Atlantic.

Hi! I started my 12 month sandwich placement almost a year ago now, having studied the first two years of my BSc in Biology at York University, returning there this October to complete my degree.  My placement has been based in Kew's Conservation Biotechnology (CB) team.

Ed Jones holding a culture jar of Anogramma ascensionis

Since 1974 the CB team has developed plant tissue culture techniques for over 3000 different plant species.  The main objective of my project has been the development of a protocol for the cryopreservation of four endangered Ascension Island ferns. The word 'cryopreservation' comes from the Greek word 'cryos' meaning 'icy cold', and thus cryopreservation means freezing living material to keep it safe. We cryopreserve our plants in liquid nitrogen at -196°C! Ascension is one of the UK's Overseas Territories (UKOTs) that was used by sailors in the 18th and 19th centuries as a staging post during long voyages. It lost much of its native vegetation as trees were felled for ship repairs and as land was cleared to grow crops. 

Why cryopreserve?

There are many reasons why we want to do this. In the CB lab we have about 300 species growing in glass jars on specially selected media containing nutrients. By keeping these plants, many of which are near extinction or critically endangered, they can be preserved for future generations to enjoy and benefit from. When the conditions are right, they can be reintroduced into the wild.


Jars of plants growing on culture media


Hundreds of tiny plant cuttings are stored in Dewars of liquid nitrogen

A whole species can be stored by taking tiny cuttings of plants, which are then transferred to Dewars filled with liquid nitrogen. Thus, plants in liquid nitrogen take up a lot less space than the same number in jars. The CB team has already successfully cryopreserved about 100 species, and has room for many more.  Being relatively inexpensive, liquid nitrogen storage can be used to reduce many costs:

  • Staff time is saved since plants no longer need to be transferred when they grow too large for their jars.
  • Plant food costs are eliminated since you don’t need to feed a plant when it is frozen.
  • Energy savings, since no artificial lighting or air conditioning is required.

Equally important is the maintenance of genetic fidelity. Many plants have been grown continuously for many months or even years in our growth room; over time there is a risk of changes in their genetic make-up due to variation in culture. Plant material can be stored in liquid nitrogen as soon as it is received; thus the risk of variation is greatly reduced.

So, what plants have I been working on?

About 2 years ago, Anogramma ascensionis was rediscovered after being thought to be extinct for about 50 years! A small section of frond was sent over from Ascension Island. With this, my predecessor, Katie Baker, managed to culture A. ascensionis spores, and built up an admirable stock of plants. I have been using material from these stocks to develop a species-specific cryopreservation protocol. This has been in addition to experiments with three other fern species, also from Ascension Island.

Freezing a plant!

Developing a protocol for cryopreservation is very species specific; one technique may result in high survival for one species, but no survival for another species. This means a lot of trial and error (and crossing your fingers!) is required as you begin to work out what works best.


Tests confirm that plantlets survive the freezing and thawing processes and grow normally


All in all it has been a great year! The team in the CB have given me a great grounding in science. I have had extensive training and, throughout my project, there have always been friendly faces to help when required.  At University, it was stressed to make sure everything in an experiment is planned extensively and recorded in great detail; my placement at Kew has emphasised this in a real-life work environment. Kew is a great place to learn. Not only are you surrounded by fascinating experienced people, but there are also an array of lunchtime seminars and evening lectures, on a diverse range of topics, that are presented by leaders-in-their-field. These have given me further direction as to where I want to go after graduating in a year's time. The project has been extremely rewarding, and knowing that you are helping to conserve plants for future generations to enjoy is a great motivator. After graduation I hope to continue with the botanical research that I have begun in Kew.

Lastly, there are many perks to working at Kew Gardens, an obvious one being the beautiful setting. However, being a lover of sweet things, I should mention that the apple and cinnamon muffin and the carrot cake in Kew’s restaurants have made this year that bit tastier!

- Ed -


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6 September 2011
How wonderful that your are preserving the rare ferns. Quite a few are involved in Pteridophytic research all over the world and conservation biology is again a very, very rare field in Pteridophytes. Hearty wishes and expecting salient achievements

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