How Do GMO Crops Work?

It’s no secret that talking to anyone about Genetically Modified Organisms (GMOs) these days is a big “no, no,” and this is true pretty much anywhere in the world. In North America, especially, it is an issue which has divided the country. Anyone who attempts to address this topic is (inevitably) called either a conspiracy theorist or a shill for the government and big business. Yet, as Professor Brian Cox recently noted, in science,

With that in mind, one needs to know the science behind GMOs in order to make informed decisions about GMOs (and either critique or endorse them). So without further ado....

The Science Behind GMOs: Bt Crops and Round-up Ready GMOs

Both Bt and Round-up Ready crops are GMOs; however, they do two completely different things. Bt Crops use a protein from the bacterium Bacillus thuringiensis to target the larvae of the order Lepidoptera (in short, Bt crops are modified so that they are deadly to caterpillar larvae that would otherwise eat the crops). Bt crops are preferred by many because the Bt endotoxin is considered safe for humans, other mammals, fish, birds, and the environment due to its selectivity—it does not harm other organisms like broad-spectrum insecticides. On the other hand, many people incorrectly believe that Round-up (also known as Rodeo and Pondmaster) plants contain glyphosate (a general use pesticide).

This is not true. What they contain is a strain from an Agrobacterium called CP4 EPSPS.

The way glyphosate works is that it obstruct the seven step metabolic route in plants, also known as the Shikimate pathway. This pathway is vital to plants and some micro-organisms, as this helps in the synthesizing of aromatic amino acids such as tryptophan, phenylalanine, and tyrosine. In humans and animals, the Shikimate pathway is not found; therefore, we must obtain these amino acids through the food we eat, particularly the phenylalanine and tyrosine amino acids (as animals can synthesize tyrosine from phenylalanine).

Now that you know what glyphosate does to plants, we can talk about the glyphosate ready crops. As stated above, Round-up Ready crops use a particular strain from an Agrobacterium called CP4 EPSPS. Agrobacterium is a bacterium that transfers its DNA to plants using lateral gene transfer (lateral gene transfer is essentially the transfer of DNA between organisms by a method other than traditional reproduction). Extensive tests have been done to see the effects from this bacterium in humans from using Agrobacterium. Studies suggest that Agrobacterium adheres to and reconstructs certain types of human cells (by genetically integrating its T-DNA into the human cell genome); however, the study did not draw any conclusions regarding related biological activity in nature.

It's also important to note that the entire bacterium isn't used, only the strain of the bacteria which produces CP4 EPSPS.

So why is this particular strain so important? Well, it's because this particular strain within the bacterium is—you guessed it—glyphosate resistant. It is this strain that is injected using a gene gun or biolistic particle delivery system into the cell of the plant to make them glyphosate ready. In turn, this lets farmers spray their crops with glyphosate i.e. Round-up, Rodeo, Pondmaster, etc. without having to worry about their crops being targeted by the glyphosate itself.

Things To Remember When Discussing GMOs:

Ultimately, it is essential to all of us that we get as much information as possible on (seemingly) controversial subjects like these. After all, if we just continue to listen to hearsay, never do research, and never engage is debates or discussions, then what purpose does science really serve? Indeed, a true scientist's goal is to form a solid understanding of the science behind certain issues in order to make decisions and form conclusions about said issues.

In the end, the best advice is to research the food you eat. Know where it comes from. Know what scientists say about it, and know where the scientists get their funding. What you don’t want to do is jump on a bandwagon when there is no indication that a sane person (one who knows what they are doing) is driving the car.

The author has not received funding (monetary or otherwise) from any individual, organization, or other body to publish or promote content. The author is not affiliated with, paid by, or otherwise influenced by any of the manufacturers of genetically modified organisms or similar bodies.

This article was originally published by All Science All the Time. Republished with permission from the author.