Endangered plants are protected in freezers


An important and possibly irreplaceable part of Ireland's heritage rests in two freezers at the Trinity College Botanic Gardens near Palmerston Park, Dublin. Wire racks hold hundreds of vacuum-sealed foil packs, each of which contains a quantity of seed.

This plant material, maintained at a chilly minus 18s0] Celsius and dessicated to just 7 per cent of its normal moisture content, could become the resource that saves many of our most endangered plants from extinction. The 165 seed collections, some of which contain up to 30,000 seeds, represent 59 of the 138 plant species classified in The Irish Red Data Book as either threatened, rare or possibly extinct.

"This is really a fallback," explained Dr Steve Waldren, curator and administrator of the Trinity Botanic Gardens. If a plant species in the wild was pushed to its limits through habitat decline the Gene Bank could serve as a "buffer against population collapse".

The Bank got under way in 1994 with a £35,000 grant from the Heritage Council. "It is really a collaboration between ourselves, the Irish Genetic Resources Conservation Trust and National Parks and Wildlife," Dr Waldren said. The newly-established trust wanted to begin a project and the partners agreed to co-operate. Running a gene bank demands much more than simply going out and collecting a few seeds. No collection has fewer than 1,000 seeds - a practical minimum, Dr Waldren said. The idea was to retrieve a "representative sample of the wild population. It must represent a picture of the genetic variation." This means collectors must bring back seeds from widely separated samples or distinct "populations" to allow as much variation as possible.

Variation is the key to genetic stability. Too small a population of any species, plant or animal, threatens its very existence because there will be too little variety to maintain a healthy stock.

Maintaining the seeds requires proper control of temperature and seed moisture content. Seeds are dehydrated slowly by storing them adjacent to silicate dessicants and moisture content is determined by weight. Once sealed in air-tight foil packs, the seeds are kept in the freezers.

Most seeds held in this way could remain viable for well over a century and up to 300 years for some varieties. The initial funding has now run out but the project continues. "Trinity College is paying the electricity but there is a need to continue maintaining the collection."

With more funding the group could broaden its collection to include additional threatened plants but also to accumulate "landrace" varieties. These are ancient or primitive varieties that traditionally would have evolved in a well-defined area with little genetic mixing, for example native grain varieties grown on the Aran Islands.

It would also be desirable to foster "complementary conservation", maintaining a seed bank for endangered species but also growing matching wild collections in nature reserves and national parks.