Gene Editing: Not as Scary as it Sounds
You have almost certainly heard the terms genetically modified organism (GMO), or gene editing at some point. Maybe you heard it on the news or on social media, or maybe you read it on your food label. Possibly you have heard strong opinions either for or against GMOs from those same sources, or even from your friends and family. But what exactly is gene editing? The definition is straightforward but does not completely answer the question: gene editing is the process of taking any organism (plant, animal, bacteria, fungus, etc.) and changing its genome.
Now you may be wondering what a genome is and how it can be changed. To put it in an analogy, a genome can be compared to a (very large) cookbook. This book would contain thousands of recipes that tell the chef how to make a variety of foods, like how a genome contains thousands of genes that tell the cell how to make a variety of proteins. Now imagine the cookbook (aka genome) for a plant like corn. The genome will tell the plant cells what proteins to make, and those proteins will determine many of the traits that the plant displays: the height of the plant, the number of kernels, how well it can withstand a drought, and much more.
As a plant scientist, I have been personally involved in studying the genes and proteins that determine plant characteristics. I am interested in how well plants can resist diseases, as disease has a major impact on the amount of food farmers are able to produce. The advent of large-scale industrial farming has led to the development of many commercial pesticides that help control plant disease, but often come at a high cost to human health and the environment. I and other researchers want to find more responsible and sustainable methods that can be integrated with non-pesticide management strategies in order to improve food security. As such, research is being conducted into how we can modify the genomes of plants to improve disease resistance and a host of other plant characteristics. But how would one go about modifying a plant genome?
One of the most basic and profound concepts in biology is that the underlying mechanism of genes and proteins is conserved across all known organisms. Going back to our recipe book analogy, this means that the language that the recipes are written in and the ingredients used for the dishes are the same between all cookbooks. Researchers can take an interesting gene from bacteria and put it into corn almost as easily as you could cut out a cornbread recipe from a Missouri cookbook and paste it in a New York cookbook. In fact, since 1995 there has been a commercially available cultivar of corn that contains a gene from a common soil bacterium. This gene tells the plant cells to produce a protein known as Bt that is toxic to insects, limiting crop damage from a moth called the European corn borer1. This process is officially known as genetic modification, which is defined as the insertion of gene from a related (cisgenic) or unrelated (transgenic) organism into. However, in many cases improving a plant can be accomplished by simply deleting one of the many genes in its genome, almost as if you were cutting out a distasteful recipe from your cookbook. This method is even faster and more precise than inserting a gene and is officially known as gene editing. The resulting organism is not a GMO, as no foreign genes remain following processing; the final product could have been generated by years of traditional breeding. A recent example is the “Tomelo” tomato, which was developed by the Sainsbury lab in England and is resistant to powdery mildew (a major disease of tomatoes)2. Unfortunately, the strict regulatory landscape for GMOs in Europe has prevented the Tomelo from being commercialized.
Regulatory bodies have been struggling for years with GMOs and how to implement them. The European Union is notoriously strict, while the US is notoriously less strict. However, even within the US it can be difficult to find agreement between government agencies. The FDA only focuses on whether the trait affects the safety of a plant as a food or drug, whereas the USDA cares about the process behind the genetic modification or gene editing and whether the inserted gene comes from a pest or weed. Controversy within the general public can get heated, with unsubstantiated and sometimes outrageous claims too easily being thrown around on the internet.
Ultimately, no one can make the decision for you whether you are comfortable with the use of gene editing in the plants you eat and use, or in the use of gene editing in other areas like medicine. My goal is to help explain a complicated topic that you may be curious about or unfamiliar with. In my opinion, and in the opinion of every plant scientist I know, both GMOs and gene editing are safe for you and your family. We have friends and family too, and just like you we do not want them to be at risk of harm.
1. Saxena, D., Flores, S., & Stotzky, G. (1999). Transgenic plants: Insecticidal toxin in root exudates from Bt corn. Nature, 402(6761), 480.
2. Nekrasov, V., Wang, C., Win, J., Lanz, C., Weigel, D., and Kamoun, S. (2017). Rapid generation of a transgene-free powdery mildew resistant tomato by genome deletion. Sci. Rep. 7, 482. doi: 10.1038/s41598-017-00578-x.