GMOs, or genetically modified organisms, have created a lot of controversy and worry as their number has increased in our food supply, and as our ability to manipulate genes has grown. Understanding how GMOs are made can aid you in understanding their importance, whether they are safe, and how to make decisions about including them in your diet.
What Are GMOs?
All plants and animals have a genetic code made up of their DNA. Encoded within the DNA are the traits and features of the plant or animal. When the scientists studying the DNA of a plant or animal isolates the DNA code for a favorable trait, they can then splice that section of DNA into a different plant or animal. If this works correctly, the resulting plant or animal will have gained the trait that the DNA code controlled. This is genetic engineering.
Genetic Manipulation before GMOs
While the technology to isolate and splice specific genes and DNA is relatively new and DNA was only discovered in the 1950s, genetic manipulation of our food supply has been going on for far longer. The ancient way manipulating genes was known as crossbreeding and selective breeding. All the vegetables that we commonly eat today are a result of selective breeding.
When our ancestors shifted from hunter-gathering to farming, they took the edible plants that they used to gather and began to cultivate them. They would crossbreed and selectively breed the plants that had the most desirable traits, such as sweeter taste, larger fruit, or greater yield. As time went on, this process became specialized and as a result several new vegetables came from one common ancestor.
Take the cabbage as an example. The family of cruciferous vegetables which includes cabbage, cauliflower, Brussels sprouts, broccoli, kale, and many other similar leafy green vegetables are all from the same species. Through thousands of years of crossbreeding and selective breeding, the different vegetables that we know and eat have been developed.
Prior to the 19th century, the mechanism to explain how crossbreeding and selective breeding worked was unknown. The 19th-century scientist and friar Gregor Mendel performed several experiments with hereditary traits in pea plants and discovered that there are dominant and recessive traits, spelling out what is now known as the laws of Mendelian inheritance. This led to a further boom in crossbreeding and selective breeding.
Reasons for Genetic Modification
Before looking at the specifics of how GMOs are made, it can be helpful to understand why we do it. There are a multitude of reasons to genetically modify plants and animals.
Get More Food
As with most of the genetic manipulation in previous generations, one of the main reasons to genetically modify any edible plant is to increase the yield or size. Increased yield means that the same amount of space and water or fertilizer investment returns greater amounts of food.
Get More Nutrition
Another reason for genetic modification is to increase the nutrient quality of the food. Adding necessary nutrients to staple foods can decrease malnutrition. Golden rice is a good example of this. Rice is one of the most important staple foods in the world, but it does not contain vitamin A. Vitamin A deficiencies kill an estimated 650,000 children under the age of five each year. Golden Rice has been genetically modified to produce vitamin A, giving it its golden color.
Make Research Easier
Beyond food use, one of the primary purposes of GMOs is to help researchers. Animals or plants can be genetically modified to be more susceptible to a certain disease being studied. This allows researchers to better study the effects of the drug being tested as well as the effects of the disease.
There is also a possibility that GMOs can be used to help control diseases. Mosquitoes carry a variety of dangerous diseases, such as West Nile virus and malaria. There have been some efforts to use genetically modified mosquitoes to reduce the total mosquito population. By genetically modifying male mosquitoes to be sterile and releasing them during the breeding season, mosquito numbers could be reduced, as fewer female mosquitoes would be impregnated and give birth.
One of the most controversial types of genetic modification is the addition of traits that make the plants resistance to pests or just generally more robust. One of the reasons world hunger is less of a problem today than we thought it would be in the 1940s is genetically modified dwarf wheat. This kind of wheat is capable of growing in more climates than ordinary wheat and produces a far greater yield. Plants that are hardier and more resistant to pests are much more difficult to control, however. The fear among many opponents of GMOs is that genetically modified plants will spread and push out native plants and harm the environment.
Invasive species are a problem worldwide already. Ecosystems are delicately balanced, and the introduction of a new plant or animal into them can have disastrous effects. There are a multitude of examples of this, but the more extreme come from ecosystems that have been isolated. Australia has the most isolated ecosystem in the world, except for Antarctica, and the introduction of mice and rabbits has destroyed the delicate balance.
As the continent had no natural predators for mice or rabbits, these rodents bred in great numbers, devastating the native flora and fauna. Plagues of mice sprang up, and millions of mice ravaged the farmland of Australia almost every four years. Despite the efforts to control the rabbit population, plagues of rabbits are not unheard of either. If GMOs become invasive, there is a fear that they could have a similar effect on ecosystem wherever they exist.
How GMOs Are Made
GMOs are made in a four-step process that begins with researchers determining a desirable characteristic in a plant or animal that they want to include in another. Next, they have to isolate the genetic code that corresponds with that desirable characteristic. The third part of the process is to remove that piece of the DNA and finally the insert that into seeds or eggs to create and then grow a genetically engineered organism.
Identifying the Trait of Interest
The first step in how GMOs are made requires researcher to find the appropriate trait to give to a new organism. The best place to find these are in nature, and the researcher has to use critical thinking along with a bit of luck to discover it. The trait of interest will differ depending on the purpose of the genetic modification. If the researchers are trying to create a crop that will grow better in a certain area, they will likely look at naturally occurring crops that thrive in that area to give the new plant the same heartiness. For crops such as golden rice, the researchers looked for other plants that were high in vitamin A.
Isolating the Trait of Interest
After finding the trait of interest, the next step is to isolate it. This is the most difficult part of how GMOs are made because the genetic makeup of even the simplest plant is incredibly complex. Researchers can map the entire genetic code of the plant, but as this is so complex it takes a lot of time and research to do it.
Other ways to isolate the trait of interest is to compare the sample’s genome with that of other members of the same species that do not have the trait. Isolating the differences can help researchers find the right genes that control the trait of interest. A final method is to hunt for the trait of interest by knocking out part of the genome of the sample plant. If the resulting plant loses the trait of interest, they have isolated the area of the genetic code where it resides.
Insert the Genetic Code with the Trait of Interest
The third step in how GMOs are made is the insertion of the genes that contain the trait of interest. This is commonly done with plants by using what are known as gene guns. Plants can often be cultivated and modified through grafting, where parts of a plant are joined to another plant. This is a common method of cultivating fruits and nuts such as apples, avocados, walnuts, and pears. Famously, in the 1800s, an insect infestation of French wine grapes was solved by grafting the French grape vines onto North American rootstocks that were resistant to the infestation.
A gene gun shoots small metal pellets that are been coated with the DNA that includes the trait of interest. This ball is shot into the plants, and as the plant continues to grow, it grafts that DNA into it. More recent methods include the use of genetically modified bacteria. Bacteria that naturally invades the seeds of plants can be modified to insert the DNA including the trait of interest instead of the DNA that would allow the bacteria to propagate itself. This uses DNA’s natural behavior for a different purpose.
Growing the Plant Containing the GMO
The easiest step and how GMOs are made is growing the GMO plant. Most GMO plants grow in the same manner as the non-genetically modified versions, but care needs to be taken to ensure that the GMO plants do not join the natural ecosystem if they could be disruptive. As the plant grows, it is tested and researched further to determine the success of the genetic modification.
GMOs are a hot topic, and as the technology that allows their creation becomes easier to use, they will increasingly be a part of our world going forward. The above introduction as to how GMOs are made should provide you with the basics that you need to understand GMOs and their place in our world.