A seed bank or germplasm bank is a place where suitable conditions are set up to conserve seed specimens of different plant species (wild or cultivated) in such a way as to guarantee the preservation of the genetic diversity of plants.
Plants are threatened too
And it is that, when talking about biodiversity or threatened species, many times the mind goes to the large groups of animals, and we forget that not only the lynx or the grouse are in danger of extinction. More than 20% of the 380,000 known botanical species in the world are threatened for various reasons: due to climatic causes, human pressure and invasive plants or a combination of all of them. In Europe, it is estimated that 50% of endemic species are in danger of extinction.
Seeds can be stored to preserve green biodiversity , and this is the goal of seed banks: to save as many plants as possible for posterity.
How are the seeds preserved?
The seeds of the specimens are kept in conditions of stable humidity, constant low temperature with little light or in the dark and in jars with labels that detail the variety, the place where they were collected and their characteristics.
“Most of the world’s plants produce seeds that can maintain their viability after being dried and frozen,” explains a document from the European network ENSCONET (European Native Seed Conservation Network). “In these cases, after harvesting and a correct classification, the seeds are cleaned and dehydrated to 5% humidity. The seeds are then enclosed in hermetically sealed containers and finally stored either in freezers at -20 ° C or in liquid nitrogen. It is important, before storing the seeds, to identify their origin so that they can be correctly classified. Seeds that cannot stand being dried need specific research to improve their viability and increase their longevity for storage. During storage, germination tests are carried out to guarantee the viability of the seeds and to ensure that the reintroduction of the species will be possible in case of extinction ”.
Are they suitable for all plant species?
Unfortunately, seed banks are not a viable option for all plants in the world. There are some, called recalcitrants, that do not withstand a certain degree of drying and cannot be easily preserved. An example: chestnuts or acorns.
A study published in the journal Nature Plants in 2018 revealed that 36% of endangered plant species cannot be stored in seed banks.
Usefulness of seed banks
As we have already said, one of the reasons for storing seeds of wild species is to guarantee their conservation ex situ , that is, outside their natural environment. Many of them come, for example, from geographical areas in the process of degradation, and the seeds of the plant species in the area are saved before they disappear from the place. In the future, and if the right conditions are met, these seeds could be used for reintroduction processes.
In addition to preserving genetic diversity, many seeds are stored so that they can be used in future research work. Seed banks are usually guarded by public institutions, and their material, like that of botanical gardens or natural history museums , is available for researchers who wish, after justifying their projects, to use it in their studies. .
Some of these banks have registered more than 1 billion seeds, including varieties of wild wheat whose cultivation is no longer profitable, but which, if they prove resistant to the parasites, could be ‘resurrected’ for planting in the future.
Seed banks in the world
Today there are about 1,500 around the planet, among which is the Svalbard Global Seed Vault ( see top image of the article ), on an island in northern Norway. Also called ‘The Seed Vault’, it was inaugurated in 2008 and the storage area is located one hundred meters under the mountain, under layers of rock between forty and sixty meters thick.
One of the reasons for locating this large genebank here is that the mountain in question contains a thick layer of permafrost, which guarantees a stable temperature of between -3 and -4 ° C. The seed storage area has an additional cooling system, to bring the seed storage temperature to minus 18 ° C and ensure that it remains constant. Climate change, which is causing permafrost to disappear around the world, also jeopardizes the suitability of the Svalbard seed bank.
Another of the benchmark banks in the world is the Millennium Seed Bank, in Wakehurst, south of London in England and, if we go to our country, we can cite as an example the Plant Germplasm Bank of the Polytechnic University of Madrid , which It preserves seeds of endemic and threatened species from the Iberian Peninsula, the Balearic Islands and the Macaronesian region, and of species from the Brassicaceae family (the cabbage family).
