Understanding the code of life

We all might have wondered one day… What makes you, you?

Well, it is DNA!

But what is DNA?

DNA is short for deoxyribonucleic acid, which is a pivot component of most forms of life, except for some viruses.

As you can see in the figure, the DNA molecule is composed of a phosphate group, a pentose, and a base. The base can be an adenine (A), guanine (G), cytosine (C), or thymine (T), which is the only thing that changes in DNA.

DNA carries genetic instructions for an organism’s traits. The difference between bases and their positions leads to significant changes in traits, like how high a tree is, or the color of a flower, for example.

DNA in food – does it matter?

DNA is found in all foods derived from living organisms, and it can be used to identify food components, track contaminants, and even assess the impact of diet on our DNA. Actually, when we eat something like a plant or meat, our body breaks down its genetic material and uses its components to build our own genes and proteins.

Scientists had found a way of manipulating the DNA of our food so agriculture could overcome some barriers it has been facing along the way. Those barriers are often related to yield, diseases, climate conditions, weed management, and forage pests. Scientists have built on the knowledge gained by farmers over centuries as farmers have cross-bred different varieties to try and overcome these production challenges.

The advantages of genetically modified food can include enhanced production, lower prices, and improved food safety. Additionally, the new generation of modified food has other direct benefits to consumers, like improved nutrition.

Going back in time

At first, humans would hunt and forage for food, but about 10,000 years ago, they started domesticating plants and animals for food. This phenomenon happened all over the world. The first crops domesticated by humans were wheat, barley, lentils, peas, rice, and potatoes. Besides been domesticated for food, crops have also been domesticated for clothing, such as cotton. Animals were also domesticated not only for milk and meat, but also their hides were used for clothing, building tent shelters, and storage. The first animals domesticated were likely the goat, sheep, and chicken in different parts of the world.

While domesticating plants and animals, early civilizations would select individuals with desired traits and breed them. Since then, we have been molding animals and plants, and those may look different from their wild counterparts. Ever since domestication started, humans changed their nomadic way of living to sedentary communities, when the density of population started to rise.

Natural selection and mutation

In the 19^th century, Charles Darwin and Alfred Russel Wallace started studying what would become the theory of evolution. One of the main bases of evolution is natural selection. From observations published in the book Origin of Species by Charles Darwin, natural selection is not about the survival of the strongest, but the fittest. Those who are more adapted to the environment will have a greater chance of survival and, therefore, of leaving offspring and keeping their genes in the population. There is also another important drive in evolution, which is mutation. Mutation is a natural phenomenon, caused by errors during DNA replication for cell division. This can end up giving the organism a deleterious characteristic (in this case, the individual with the mutation will die), a neutral characteristic (there is no advantage or disadvantage for this individual, so it will live like the others), or even a positive characteristic (here, the individual with the mutation will thrive in the population, leaving more offspring and spreading its mutated genetic code – look at the brown beetle example in the figure).

Methods of plant modification

Artificial selection is where the pressure is a human choice. We choose plant or animal individuals with the best features and then breed them so their offspring may have all the desired features. One example is the wild mustard, which has been used to select different features, creating different crops such as cauliflower, broccoli, cabbage, kohlrabi, and kale.

Humans would do that without even knowing about the existence of DNA. But since the discovery of DNA in the late 1860s, humans have been developing techniques to understand and manipulate it, especially when it was related to food production. With the advent of agriculture, human settlements started growing, and the population increased, which then needed even more food to support the number of people.

Although humans have been using selective breeding (artificial selection) for thousands of years, it is a very slow and random process, only working between varieties of the same species (check the next blogs of this series for more information). In the 1980s, scientists began using transgenic breeding, a technique that has been employed to this day. In transgenic breeding, a gene is inserted from one species into another, regardless of whether they are related (check the next blogs of this series for more information).

There are also other methods of plant modification. Mutagenic breeding can be faster than conventional breeding. Since mutations occur naturally and randomly in nature, mutagenic breeding induces mutations using radiation or chemicals, until a positive mutation is identified and selected (check the next blogs of this series for more information).

Interference RNA is used to silence a gene. For example, the production of a specific protein in a plant is suppressed and that will no longer be produced (check the next blogs of this series for more information).

Finally, gene editing is the newest technology available for plant modification (check the next blogs of this series for more information). Gene editing holds the power to increase food production by being a simple method with many applications. Those applications include abiotic stresses like drought, cold, oxidative stress, heat, salt, UV exposure, and heavy metals; biotic stresses such as viruses, nematodes, bacteria, pests, fungi, and parasitic plants; and enhance crop yield and quality with increased photosynthetic efficiency, improving taste, texture, and shelf life, supporting biofortification, and regulating hormone production. Gene editing regulation is still in progress in some countries, but in many countries it is already considered as non-genetically modified (see blog on gene editing regulation), while others still regulate them as genetically modified. Global adoption and compatible regulations of genetically modified crops is essential for a more secure and sustainable future.