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United States Department of Agriculture

Agricultural Research Service

What are GMO'S?
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Frequently in the news there is discussion regarding the use of GMO's in crops and foods. The term "genetically modified organism" (GMO) was originally used by the molecular biology scientific community to denote a living organism that had been genetically modified by inserting a gene from an unrelated species. Incorporation of genes from an unrelated species does not occur in nature through sexual reproduction and thus, various types of sophisticated technologies are used to accomplish this. These types of plants are generally called "transgenics". Transgenic technology has been used in over 40 species of plants including corn, cotton, tomatoes, potatoes, soybeans, tobacco, rice, cranberries, papayas, raspberries, chrysanthemums, gladioli, petunias, poplars, spruce, and walnuts. In crop plants, the technology has generally been used to incorporate insect resistance or herbicide tolerance. More recently, transgenic rice strains having high vitamin A or high iron content have been developed. In the future, transgenic plants may be used as "bioreactors" to produce large quantities of inexpensive pharmaceuticals, polymers, industrial enzymes, as well as modified oils, starches, and proteins.

 

How Are Genetically Modified Organisms Different From
The End-Products of Conventional Breeding?

Organisms that are highly related can usually intermate through sexual reproduction. Most conventional breeding efforts are focused on making crosses amongst highly related strains of a species and then selecting among the offspring. This same sort of crossing takes place in nature. The difference between what occurs in nature and in a breeding program, is that the breeder selects which two strains to intermate through crossing. Such conventional breeding methods have been used as long man has tried to domesticate plants and animals.

The more unrelated two organisms are, the less likely that sexual reproduction would successfully result in viable offspring. Several decades ago breeding methods were developed that allow for closely related species or even somewhat distantly related species to be successfully mated. This allowed for the transfer of useful genes from related species into crop plants that may not have normally survived in nature because it would be such an extremely rare event. With these methods, breeders had access to a wider range of genes that occurred in nature to improve crop plants. Tremendous success has been demonstrated in crops by using these genes for building resistance to insects and diseases and for tolerance to abiotic stresses.

Biotechnology methods have now been developed that allow researchers to completely by-pass sexual reproduction and directly insert a gene into a cell that will be the basis of a new plant. Thus, new combinations of genes can be created in a genetically modified organism that would never be found in nature. The recently developed "Golden Rice" is an example of a GMO that has enhanced Vitamin A content due to the incorporation of genes from a microbe and from daffodils into rice. Regular white milled rice has insignificant levels of Vitamin A. Thus, Vitamin A enhanced rice may improve the diet of people in third world countries that rely upon rice as their main food source.


Last Modified: 2/23/2005