When is a GMO not a GMO?

Everything we eat has been genetically modified but no one would call crops from common crossbreeding GMOs. No, Genetically Modified Organisms occur when DNA from one species is inserted another. So-called transgenic crops, such as corn and soybeans, are resistant to the herbicide Roundup. Use of the technology has led to public distrust of GMOs.

crossbreeding

But other technologies modify genetics yet they are not defined as GMOs. With the arrival of the precision gene-editing tool called CRISPR, definitions become more than just semantic says Scientific American (March, 2016). If the foods produced by CRISPR are not defined as GMOs, then public acceptance will be greater.

Let’s look at some current technologies that are not defined as GMOs. The oldest is conventional crossbreeding, widely regarded as “natural.” If we want a blight-resistant plant that produces desirable fruit, a wild relative of the plant that is blight-resistant can be cross-pollinated with one that produces desirable fruit. However, this process is not precise –it transfers not only the desirable trait but also large segments of chromosomes. Along with the desirable chromosomes can be undesirable ones; a process called “linkage drag.”

Modern wheat is one of those. Nina Fedoroff, a plant biologist and former president of the American Association for the Advancement of Science, refers to domesticated versions of bread wheat created by traditional breeding as “genetic monstrosities.”

Then there is Mutagenesis, not considered as creating GMOs by the U.S. Department of Agriculture. Developed in the 1920s, it involves the use of x-rays, gamma rays or chemicals to induce mutations in plants. The mutants are ten examined for desirable traits. It’s a shot in the dark.

A more precise shotgun approach was refined in the 1980s. Cisgenesis involves using a DNA particle gun to literally shoot genes with the desirable trait into a plant cell. Cisgenesis can also be accomplished by using bacteria to carry the desirable genes into the plant cell. It’s more efficient than conventional crossbreeding because there is less linkage drag. Whether or not the product is a GMO is determined on a case-by-case basis.

Gene-spliced plants are not considered GMOs. In this method, undesirable traits are turned off by introducing RNA into genes which interferes with the gene. Some approved foods using this method are non-browning potatoes and apples.

CRISPR is totally new and the jury is out on whether they produce GMOs or not. The precision and low-cost of CRISPR confound the problem. As I described in an earlier column, CRISPR is like a search and replace function in a word processor in which all instances of a spelling error can be found and replaced.  Or it can be used to find and simply delete the error.

Supporters of CRISPR argue that when the technology is used to delete but not insert genes, then the results should not be called GMOs: as when an undesirable trait is deleted and not replaced with anything.

Critics of CRISPR say that any tinkering with genes using any technology, other than “natural” methods, should be enough to label the products as GMOs.

Clearly, public acceptance relies on accurate definitions.

 

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