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| Steffen Dietzel, courtesy of Wikimedia Commons |
The Random House dictionary definition:
[A]n organism or microorganism whose genetic material has been altered by means of genetic engineering.
Merriam Webster doesn't have a definition of GMO, but defines genetic engineering:
[T]he group of applied techniques of genetics and biotechnology used to cut up and join together genetic material and especially DNA from one or more species of organism and to introduce the result into an organism in order to change one or more of its characteristics. (Take a deep breath after that one.)
The World Health Organization's contribution:
Genetically modified organisms (GMOs) can be defined as organisms in which the genetic material (DNA) has been altered in a way that does not occur naturally. The technology is often called "modern biotechnology" or "gene technology", sometimes also "recombinant DNA technology" or "genetic engineering". It allows selected individual genes to be transferred from one organism into another, also between non-related species.
The European Union's legal definition:
An organism is "genetically modified", if its genetic material has been changed in a way that does not occur under natural conditions through cross-breeding or natural recombination.1
Finally, the US Food and Drug Administration's regulatory definition:
In the case of foods, genetically engineered plant foods are produced from crops whose genetic makeup has been altered through a process called recombinant DNA, or gene splicing, to give the plant desired traits. Genetically engineered foods are also known as biotech, bioengineered, and genetically modified, although "genetically modified" can also refer to foods from plants altered through methods such as conventional breeding.
So there you go -- clear as mud. However, the general consensus is that genetically modified organisms are plants (or animals) altered by individual-gene splicing methods which have been developed in the last 30 years. The term "GMO" generally refers to organisms deliberately modified by viruses, bacteria, "gene gun", injection, electrical shock, or chemical poration, to carry a specific set of new genes that they didn't have before. It doesn't usually include mutation (by radiation or chemicals), so-called "wide crosses" where distant cousins are bred together, various hybrids, or cloning plants from a single cell or growing point.
Even before the advent of real gene splicing, we were messing with our food to a serious degree. Many people point to corn, which was bred up from a grassy weed, as an example of how we've always manipulated food plants.2 What I think of, however, are the more recent developments of ruby red grapefruit and seedless watermelons. "Star Ruby", the first of the seedless red grapefruits, was the result of treating grapefruit seeds with radiation.3 Seedless watermelon plants are hybrids, made by crossing a regular watermelon with one which has been treated with a chemical to double its chromosomes; the child of that cross has three of each chromosome, which short-circuits its seed production.4 It would have taken hundreds or thousands of years to breed these plants by traditional methods, though it is theoretically possible. Both mutations and doubled chromosomes happen in nature.
GMOs, by contrast, couldn't be made using old-world methods at all. One of the definitions of species is whether two individuals can successfully breed; a plant (corn) and a bacterium (Bacillus thuringiensis) are too far apart to cross. We have enough trouble breeding together cousins like wheat and rye, and only succeeded with the aid of the chemical colchicine.5 So a crop like Bt corn, which has genes from Bacillus thuringiensis inserted into it to repel pests, could only come out of the modern methods I mentioned above.
Now that we have some idea of the result, the next step is to look at those methods. That will be the next post.
[This article is part of the series on GMOs. Jump to the first post for an overview and index.]
