What are GMOs (Genetically Modified Organisms)?

A genetically modified organism or GMO is any life form—a plant, animal, or microbe—that has had its DNA changed. When people hear this term, alarm bells often ring in their head as it fills with thoughts of science fiction monsters. However, GMOs are all around us.

We’ve genetically modified bacteria to secrete life-saving insulin, while cheese and vaccines are also products of genetic engineering. When it comes to most of these applications, we don’t bat an eye, but when it comes to our food, specifically the plants we eat, people have some serious objections. The debate swings between: GMOs could either save humanity or be the reason for global food insecurity.

We grow GM crops on nearly 185 million hectares in 26 countries, including 19 developing countries. That’s roughly 12% of the global cropland. We regularly produce GM soybean, corn, cotton, alfalfa, canola, apples, papaya, potatoes, summer squash, sugar beets, and pineapple.

But what does it mean for a plant to be a GMO? In some ways, “genetically modified” is a misnomer, and also quite vague, revealing little about what genetics have been modified. All the food you eat today, be it rice, corn or watermelons, are not what they were when humans first started farming 10,000 years ago.

Corn, or maize, originated from the weed-like Teosinte, whereas watermelons used to be white and unappetizing. We have our modern crops because earlier humans manipulated plant genetics. We simply grew seeds from plants that had a desirable trait, such as more kernels, or it grew quicker or was sweeter.

Plant breeders around the world still follow a similar process, but now they’re equipped with knowledge about DNA and plant genetics. This is why we have so many different varieties of vegetables. This is called artificial selection, but there are a few limitations to this approach.

First of all, breeders can only transfer genes between closely related species. Thus, if the required trait is not present in the same or a closely related species, it cannot be introduced. Second, in traditional breeding, there is no control over how many genes from the donor plant will be introduced, leading to undesirable traits.

Third, traditional breeding takes a very long time. The breeders must cross the varieties, grow them out, harvest seeds, and repeat the cycle multiple times. This can take years, especially for species such as apples or conifers, which take many years to bear fruit.

Then, around the mid-20th century, new technologies arrived with which we could make more precise changes in the DNA of any organism. This was the birth of genetic engineering. With genetic engineering, you can move a specific gene from one organism to another, even if they belong to different species.

A gene is a functional unit of heredity. This means that we inherit genes from our parents and our kids inherit our genes. Genes contain instructions for the proteins and enzymes that make sure we are able to carry out all our functions, such as breathing, eating, digesting and so on.

When we transfer a gene within the same species, it is called cisgenics. However, with genetic engineering, you can also take a gene from a human, for example, and insert it into a bacteria. This is how bacteria can produce insulin.

This type of interspecies gene transfer is called transgenics. And GM crops are transgenics. Now, creating a GM crop is a long process that can take several years, but it can be summarized into four broad steps.

First, we need to identify what trait to add into the recipient plant and the gene that gives an organism that desired trait. Second, we need to make copies of the gene from the organism that has the desired trait. Third, we insert that gene into the DNA of the recipient plant.

Fourth, we grow GM plants. To explain this process in a bit more detail, let’s take the specific example of Bt corn, one of the world’s most widely grown GM crops. If you want to skip the technical bits, you can jump ahead to the time stamp on the screen.

Insect pests are a huge concern for farmers. They eat crops and significantly lower yields. Insecticides kill the insects, but have harmful side effects for both humans and the environment.

But what if you didn’t have to use pesticides and could still prevent pests from harming your crop? Scientists on the lookout for a solution found one in a bacteria called Bacillus thuringiensis (Bt). The bacteria produces a protein that’s toxic to insects.

Farmers often spray the bacteria on fields as an organic pesticide, but it isn’t very effective. Now, what if a corn plant could produce the Bt protein on its own? From the bacteria, you could isolate the particular gene that is a blueprint for making the protein.

Then, you would make copies of the Bt gene and insert it into the plant’s DNA. To insert a foreign gene into the plant, you’ll need a vehicle, so to speak, with a special entry pass that can carry the gene into the plant. This vehicle is called a vector.

The most commonly used vector is a bacterium called Agrobacterium tumefaciens. The bacterium is commonly found in soil and it causes a disease called crown gall disease in plants. It does this by inserting a piece of its DNA into the plant’s cells!

It essentially makes a GMO for its own uses. This bacterium has a piece of DNA known as a Ti plasmid. The bacteria sends this Ti plasmid into the plant cells by making a tunnel into the plant's cells.

Within this plasmid is a small portion called T-DNA. This T-DNA will insert itself into the plant cell’s DNA and become a part of the plant’s DNA. Scientists can modify this Ti plasmid.

They use enzymes, the molecular versions of scissors and glue, to redesign the T-DNA to add the Bt gene. Additionally, you could also use a ‘gene gun’ to insert the piece of DNA into the plant cell. When using a gene gun, heavy metal particles are coated with the gene of interest and bombarded on the cell using mechanical force.

This process is less specific than the Agrobacterium method. In the former approach, you introduce the vector into Agrobacterium using a gentle electrical pulse. Agrobacterium will infect corn embryo cells.

The corn cells are grown under tissue culture conditions to form a blob of corn cells, called a callus. These calli are dipped in the Agrobacterium solution to allow the bacteria to infect the cells. After a few weeks, you transfer the surviving corn calli to a new medium with specific hormones that ensure that the calli will regenerate into tiny plants with roots and shoots.

When these tiny plants are strong enough, they are transferred to soil in pots and grown in a greenhouse. However, you’re not done yet! — These newly transformed plants will need to undergo rigorous testing to ensure that the transgene has been inserted in the right place, that it’s doing what it is supposed to do, and that there are no unexpected or undesirable effects in the plant.

It is only after several years of safety data have been collected that scientists can approach regulatory agencies, such as the EPA, USDA, FDA, and APHIS in the USA, to get approval for commercial release. Part of getting regulation is proving that the modified crop won’t cause any allergic reactions, and that it is nutritionally similar to a traditional crop. — The media often labels GM crops as frankenfood, but the technology comes from a bacteria that performs such genetic manipulation in nature all the time.

Breeders typically only introduce 2-3 genes through Agrobacterium-mediated genetic engineering. They are also able to track the exact location in the genome where the new gene is introduced. This makes genetic engineering more precise and quicker than traditional breeding.

So far, we’ve modified papaya to be immune against the virus that infects papaya. We’ve engineered cash crops such as corn, soybeans and cotton to produce a bacterial toxin that can kill insect pests, which means less pesticide use. And we’ve engineered other cash crops to not die from herbicides, so they only kill weeds.

Most GM crops are used to feed animals in the meat and dairy industry, or used in packaged and ultra-processed foods like cereal or chips, or in the case of GM cotton, in the textile industry. GM food crops that are commercially available have been tested and shown to be nutritionally identical to traditionally bred varieties, except when the introduced trait is a nutrition trait, as in the case of golden rice, which produces higher levels of a precursor of vitamin A. GM crops have been around for almost 30 years with no credible adverse effects shown in humans or animals.

That said, concerns about GM crops are related to health, the environment, and largely center on social and economic factors. How much control will the companies that develop and sell these crops have on our food? Those are questions that go beyond GM crops into the state of agriculture today and its potential future to feed a world, especially considering the climate change crisis.

Check out the description below for a list of resources on GM crops and the ongoing debate surrounding this hot button issue.