Gene bank

The term gene bank refers to any system by which the genetic composition of some population is identified and stored. Many different kinds of gene banks have been established for many different purposes. Perhaps the most numerous gene banks are those that consist of plant seeds, known as germ banks.

The primary purpose for establishing a gene bank is to preserve examples of threatened or endangered species . Each year, untold numbers of plant and animal species become extinct because of natural processes and more commonly, as the result of human activities. Once those species become extinct, their gene pools are lost forever.

Scientists want to retain those gene pools for a number of reasons. For example, agriculture has been undergoing a dramatic revolution in many parts of the world over the past half century. Scientists have been making available to farmers plants that grow larger, yield more fruit, are more disease-resistant, and have other desirable characteristics. These plants have been produced by agricultural research in the United States and other nations. Such plants are very attractive to farmers, and they are also important to governments as a way of meeting the food needs of growing populations, especially in Third World countries.

When farmers switch to these new plants, however, they often abandon older, more traditional crops that may then become extinct. Although the traditional plants may be less productive, they have other desirable characteristics. They may, for example, be able to survive droughts or other extreme environmental conditions that new plants cannot.

Placing seeds from traditional plants in a gene bank allows them to be preserved. At some later time, scientists may want to study these plants further and perhaps identify the genes that are responsible for various desirable properties of the plants. The U.S. Department of Agriculture (USDA) has long maintained a seed bank of plants native to the United States. About 200,000 varieties of seeds are stored at the USDA's Station at Fort Collins, Colorado, and another 100,000 varieties are kept at other locations around the country.

Efforts are now underway to establish gene banks for animals, too. Such banks consist of small colonies of the animals themselves. Animal gene banks are desirable as a way of maintaining species whose natural population is very low. Sometimes the purpose of the bank is simply to maintain the species to prevent its becoming extinct. In other cases, species are being preserved because they were once used as farm animals although they have since been replaced by more productive modern hybrid species. The Fayoumi chicken native to Egypt, for example, has now been abandoned by farmers in favor of imported species. The Fayoumi, without some form of protection, is likely to become extinct. Nonetheless, it may well have some characteristics (genes) that are worth preserving.

In recent years, another type of gene bank has become possible. In this kind of gene bank, the actual base sequence of important genes in the human body will be determined, collected, and catalogued. This effort, begun in 1990, is a part of the Human Genome Project effort to map all human genes.

See also Agricultural revolution; Extinction; Genetic engineering; Population growth

[David E. Newton ]

RESOURCES

PERIODICALS

Anderson, C. "Genetic Resources: A Gene Library That Goes 'Moo'." Nature 355 (January 30, 1992): 382.

Crawford, M. "USDA Bows to Rifkin Call for Review of Seed Bank." Science 230 (December 6, 1985): 1146–1147.

Roberts, L. "DOE to Map Expressed Genes." Science 250 (November 16, 1990): 913.

gene bank An establishment in which both somatic and hereditary genetic material (see GERM PLASM) are conserved. It stores, in a viable form, material from plants that are in danger of extinction in the wild and cultivars that are not currently in popular use. The stored genetic information can be called upon when required. For example, a crop may be needed that possesses a quality (e.g. tolerance to adverse climatic conditions) which cannot be found in currently exploited cultivars but was present in more antiquated varieties. The normal method of storage is to reduce the water content of seed material to around 4 per cent and keep it at 0°C. (Pollen material may also be used but its longevity is considerably less.) Stored this way, the material often remains viable for 10–20 years. When the desiccating process proves fatal, as is the case with tropical genera producing recalcitrant seeds, where possible the material is maintained by growth. This may require considerable space, but in some cases the problem can be resolved using tissue-culture methods. All stored stock is periodically checked by germination.

gene bank An establishment in which both somatic and hereditary genetic material are conserved. It stores, in a viable form, material from plants that are in danger of extinction in the wild and cultivars which are not currently in popular use. The stored genetic information can be called upon when required. For example, a crop may be needed that possesses a quality (e.g. tolerance to adverse climatic conditions) which cannot be found in currently exploited cultivars but was present in more antiquated varieties. The normal method of storage is to reduce the water content of seed material to around 4 per cent and keep it at 0°C (pollen material may also be used but its longevity is considerably less). Stored this way, the material often remains viable for 10–20 years. When the desiccating process proves fatal, as is the case with tropical genera producing recalcitrant seeds, where possible the material is maintained by growth. This may require considerable space, but in some cases the problem can be resolved using tissue-culture methods. All stored stock is periodically checked by germination. See also seed bank.

gene bank Genetic material kept for future possible use. Material stored includes cultures of bacteria and moulds; seeds, spores, and tubers; frozen sperm, eggs, and embryos; and even live plants and animals. The material can be used in plant and animal breeding, genetic engineering, and in medicine. Live specimens are used for restocking natural habitats in which species are in danger of extinction.

gene bank See gene library.