Gene bank

This article is about preservation of genetic material. For gene banks in Molecular Biology, a collection of DNA from one organism, see Genomic library. For Duke University star and former NBA basketball player, see Gene Banks.

The active gene bank of the International Crops Research Institute for the Semi-Arid Tropics in Patancheru, India.

Gene banks are a type of biorepository that preserves genetic material. For plants, this is done by in vitro storage, freezing cuttings from the plant, or stocking the seeds (e.g. in a seedbank). For animals, this is done by the freezing of sperm and eggs in zoological freezers until further need. With corals, fragments are taken and stored in water tanks under controlled conditions. Genetic material in a 'gene bank' is preserved in a variety of ways, such as freezing at -196 °C in liquid nitrogen, being placed in artificial ecosystems, or put in controlled nutrient media.

In plants, it is possible to thaw the material and propagate it. However, in animals, a living female is required for artificial insemination. While it is often difficult to use frozen animal sperm and eggs, there are many examples of it being done successfully.

In an effort to conserve agricultural biodiversity, gene banks are used to store and conserve the plant genetic resources of major crop plants and their crop wild relatives. There are many gene banks all over the world, with the Svalbard Global Seed Vault being considered the most famous one.

The database of the largest gene banks in the world can be queried via a common website, Genesys. A number of global gene banks are coordinated by the CGIAR Genebank Platform

Types of gene bank

Inside Svalbard Global Seed Vault

Seed bank

Seed banks, also known as seed vaults. are large repositories where seeds of many different species are stored at freezing temperatures. They are used to preserve genetic diversity for the future. The storage temperature depends on how long the seeds are to be kept. Durations of 3–5 years (short term storage), 10-15 years (medium term storage) and 50+ years (long term storage) will typically have storage temperatures of 5 to 10 °C (41 to 50 °F), 0 °C (32 °F) and −18 to −20 °C (0 to −4 °F) respectively. Spores, such as those from pteridophytes can also be stored. However, storage organs, such as the tubers made by root vegetables, cannot be stored. It is also important that when seeds are stored, the moisture content of the seeds and the surrounding medium is kept low, otherwise the seeds will not be viable after long periods in freezing temperatures. The largest seed bank in the world is the Millennium Seed Bank housed at the Wellcome Trust Millennium Building (WTMB), located in the grounds of Wakehurst Place in West Sussex, near London.

Beans stored at a seed vault

In vitro bank

In this technique, buds, protocorm and meristematic cells are preserved through particular light and temperature arrangements in a nutrient medium, which is either a gel or in liquid form. This technique is used to preserve seedless plants and plants that reproduce asexually or that require preservation as clones such as commercial cultivars.

Cryobank

In this technique, a seed or embryo is preserved at very low temperatures. It is usually preserved in liquid nitrogen at −196 °C (−320.8 °F). By freezing the seeds or embryos at this temperature they can stay viable for at least a century. This is helpful for the conservation of species facing extinction. Cryobanks are utilized for the cryoconservation of animal genetic resources. An example of one of the world’s largest animal cryobanks is the frozen zoo made by the San Diego Zoo, in San Diego California. With animal cryobanks freezing embryos is preferred instead of the separate egg and sperm because the embryos are more resistant to the freezing process.

USDA cryopreservation gene bank

Storage of pollen

Pollen is stored through a cryopreservation technique called vitrification. Vitrification in this context is based around the freezing of pollen grains without the formation of ice crystals, which would heavily damage the pollen. The pollen, which is stored in liquid nitrogen, is kept at temperatures of −180 to −196 °C (−292.0 to −320.8 °F). The National Seed Storage Lab in Fort Collins, Colorado currently uses this technique to store pollen. Pollen can also be freeze dried and stored at temperatures of 5 to −18 °C (41 to 0 °F). An important element that must be considered is the levels of moisture in the pollen. If the pollen grains have a low moisture content it helps increase the length of the pollen’s life. Low levels of moisture help the pollen freeze without creating ice or ice crystals, which helps preserve the life span of the pollen while it is being stored. Ideal levels of moisture content to be allowed in the pollen depends on the type of plant. The pollen from different plant species can be divided into two groups. One is Binucleate pollen, which has a thicker exine and the second is Trinucleate pollen, which has a thinner exine. Binucleate pollen has a higher lifespan when frozen at a low moisture level. Trinucleate pollen, however, has a higher lifespan when frozen at a high moisture level. Moisture level in the pollen can be decreased by exposing the pollen to diluted salt solutions, silica gel and dry air or by chemical treatment with vitrification solutions.

Field gene banks

Field gene banks are gene banks based around the management of live specimens, in contrast to a seed bank which is focused on the facilitation of backups of germplasm, typically in the form of seeds. Field gene banks are vulnerable to natural disasters, pests and disease. As such, they are typically used as a method of last resort if a species can not be preserved via normal means, such as if it didn't produce seeds. This method also uses more land, energy and water then other methods. One example of preservation via this method is the preservation of varieties of rice, in which 42,000 varieties of rice are conserved by the National Rice Research Institute in Orissa.

Field gene bank in Malaysia

See also

• Sperm bank
• Ova bank
• Biobank
• Biological database
• Germplasm
• Seed bank
• Plant genetic resources
• Multi-Crop Passport Descriptor (MCPD)

References

• Ellis, R.H., T.D. Hong and E.H. Roberts (1985). Handbook of Seed Technology for Genebanks Vol. II: Compendium of Specific Germination Information and Test Recommendations. IBPGR (now Bioversity International). Rome, Italy. Archived from the original on 11 December 2008.{{cite book}}: CS1 maint: multiple names: authors list (link)
• Engels, Jan; Visser, Bert, eds. (2003). A Guide to Effective Management of Germplasm Collections. CABI, IFPRI, IPGRI, SGRP. Archived from the original on 25 May 2007. 174 p.
• Kameswara, N., J. Hanson, M. E. Dulloo, K. Ghosh, A. Nowell and M. Larinde. (2006). Manual of Seed Handling in Genebanks. Bioversity International, CTA (Technical Center for Agricultural and Rural Cooperation), FAO, ILRI. Archived from the original on 21 January 2008.{{cite book}}: CS1 maint: multiple names: authors list (link) 147 p.
• Koo, B., Pardey, P. G., Wright, B. D.; et al. (2004). Saving Seeds. CABI, IFPRI, IPGRI, SGRP. Archived from the original on 11 December 2008.{{cite book}}: CS1 maint: multiple names: authors list (link)

External links

• AEGIS A European Genebank Integrated System
• The Crop Genebank Knowledge Base
• Genebanks
• Genesys
• DAD-IS: Domestic Animal Diversity Information System