Seedbank
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The preservation of plant germplasm in seedbanks, (or genebanks), is one of the techniques of ex-situ conservation of plant species.
Seeds have a natural dormancy feature, which allows for their suspended preservation for long periods of time with little damage, provided the conditions are favorable. Banking dormant seeds enables to keep genetically representative samples of rare and endangered plant species as a kind of "genetic insurance".
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Role of seedbanking in conservation
Genetic diversity among plant species has a significant impact on human life. For example, many of our medical products have come from plants. It is not known which other plants could later on prove beneficial. The preservation of diversity is therefore important to human life. Many think plants must survive in order for their benefits to be discovered.
In-situ conservation of plant species is usually thought to be the ultimate conservation strategy. However, its implementation is not always possible. For example, it can not be used to prevent extinction of endangered or rare species whose habitats are disappearing. Such situation is better dealt through (or with) ex-situ conservation.
Seeds storing
Storing germplasm in seedbanks is both inexpensive and space efficient. It allows preservation of large populations with little genetic erosion. Seedbanks also offer good sources of plant material for biological research, and avoid disturbance or damage of natural populations.
Two types of seeds may be considered.
- The orthodox seeds are those that can be dried at low humidity and stored at low temperatures. These orthodox seeds can remain viable for many years and are rather easily stored in seedbanks.
- The recalcitrant seeds do not tolerate low humidity and temperature, and thus are not good candidates for seedbanking conservation.
Preparation for storage are different for each species and has to be assessed before any conservation planning. Roughly, the different processes imply first collection of the seeds, then drying to a moisture content of less than 6%. The seeds are then stored at low temperature (below -18°C). As seeds tend to lose germinative power over time, monitoring of viability and regeneration processes must be done frequently.
Seedbanks in the world
According to the FAO, there are about 6 millions plants stored through seed storing in about 1300 genebanks. This amount represents a small fraction of the diversity, and many important regions have not been bioprospected yet.
Some of the challenges facing conservation through this technique are :
- varieties stored tend to adapt to the storage conditions, and they have to be regularly replanted to stay viable. Besides, only a limited number of specimens are stored and it is impossible to store recalcitrant seeds. Finally, most of the seeds stored are field plants. Only 15% of all seedbanked plants are wild species or weed species.
- there is a need for improvement of cataloguing and data management. The documentation should include identity of the plant stored, location of the sampling, number of seeds stored and viability state. Other information, such as farming systems in which the crops were grown -or rotations they formed- should also be available to future farmers. More globally, there is a need for global documentation, that could be shared between all the genebanks; research facilities, and farmers across the world
- the human and financial cost of facilities running are sometimes too expensive for some collections. In particular, collections in the South and Eastern Europe are underfunded and poorly staffed.
- there is a need for storage of developing countries food seeds. Seedbanks and funders are confronted to the issue of creating collections without being accused of biopiracy, through providing a free resource for seed companies in rich countries.
It is widely believed the protection of plant diversity is essential for food security in particular. There are some international agreements recommanding the establishment of regional diversity conservation projects, such as Agenda 21. In the spirit of the Convention on Biological Diversity, conservation through seedbanking need to further favor information and technology transfert, as well as benefit sharing. Also, foundation of a Global Conservation Trust might help to develop or maintain some of the world most important collections.
However, some also believe inappropriate to depend on national or international projects to look after biodiversity. These latter support the development of networks of seed savers and plant breeders to look after biodiversity through the creation of living seed banks.
See also
- conservation
- biodiversity
- sustainability
- List of Conservation topics
- International Treaty on Plant Genetic Resources for Food and Agriculture
- agroecology
External links
- loss of biodiversity (http://www.primalseeds.org/bioloss.htm)
- Millennium Seed Bank Project (http://www.kew.org/msbp/)
- www.grain.org