A University of California, Berkeley professor stands at the front of the room, delivering her invited talk about the potential of genetic engineering. Her audience, full of organic farming advocates, listens uneasily. She notices a man get up from his seat and move toward the front of the room. Confused, the speaker pauses mid-sentence as she watches him bend over, reach for the power cord, and unplug the projector. The room darkens and silence falls. So much for listening to the ideas of others.
Many organic advocates claim that genetically engineered crops are harmful to human health, the environment, and the farmers who work with them. Biotechnology advocates fire back that genetically engineered crops are safe, reduce insecticide use, and allow farmers in developing countries to produce enough food to feed themselves and their families.
Now, sides are being chosen about whether the new gene editing technology, CRISPR, is really just “GMO 2.0” or a helpful new tool to speed up the plant breeding process. In July, the European Union’s Court of Justice ruled that crops made with CRISPR will be classified as genetically engineered. In the United States, meanwhile, the regulatory system is drawing distinctions between genetic engineering and specific uses of genome editing.
Joe Cavaretta/AP Photo
I am a plant molecular biologist and appreciate the awesome potential of both CRISPR and genetic engineering technologies. But I don’t believe that pits me against the goals of organic agriculture. In fact, biotechnology can help meet these goals. And while rehashing the arguments about genetic engineering seems counterproductive, genome editing may draw both sides to the table for a healthy conversation. To understand why, it’s worth digging into the differences between genome editing with CRISPR and genetic engineering.
What’s the difference between genetic engineering, CRISPR and mutation breeding?
Opponents argue that CRISPR is a sneaky way to trick the public into eating genetically engineered foods. It is tempting to toss CRISPR and genetic engineering into the same bucket. But even “genetic engineering” and “CRISPR” are too broad to convey what is happening on the genetic level, so let’s look closer.
In one type of genetic engineering, a gene from an unrelated organism can be introduced into a plant’s genome. For example, much of the eggplant grown in Bangladesh incorporates a gene from a common bacterium. This gene makes a protein called Bt that is harmful to insects. By putting that gene inside the eggplant’s DNA, the plant itself becomes lethal to eggplant-eating insects and decreases the need for insecticides. Bt is safe for humans. It’s like how chocolate makes dogs sick, but doesn’t affect us.
Another type of genetic engineering can move a gene from one variety of a plant species into another variety of that same species. For example, researchers identified a gene in wild apple trees that makes them resistant to fire blight.They moved that gene into the “Gala Galaxy” apple to make it resistant to disease. However, this new apple variety has not been commercialized.
Scientists are unable to direct where in the genome a gene is inserted with traditional genetic engineering, although they use DNA sequencing to identify the location after the fact.
In contrast, CRISPR is a tool of precision.
Just like using the “find” function in a word processor to quickly jump to a word or phrase, the CRISPR molecular machinery finds a specific spot in the genome. It cuts both strands of DNA at that location. Because cut DNA is problematic for the cell, it quickly deploys a repair team to mend the break. There are two pathways for repairing the DNA. In one, which I call “CRISPR for modification,” a new gene can be inserted to link the cut ends together, like pasting a new sentence into a word processor.
In “CRISPR for mutation,” the cell’s repair team tries to glue the cut DNA strands back together again. Scientists can direct this repair team to change a few DNA units, or base pairs (A’s, T’s, C’s and G’s), at the site that was cut, creating a small DNA change called a mutation. This technique can be used to tweak the gene’s behavior inside the plant. It can also be used to silence genes inside the plant that, for example, are detrimental to plant survival, like a gene that increases susceptibility to fungal infections.
Rebecca Mackelprang, CC BY-SA
Mutation breeding, which in my opinion is also a type of biotechnology, is already used in organic food production. In mutation breeding, radiation or chemicals are used to randomly make mutations in the DNA of hundreds or thousands of seeds which are then grown in the field. Breeders scan fields for plants with a desired trait such as disease resistance or increased yield. Thousands of new crop varieties have been created and commercialized through this process, including everything from varieties of quinoa to varieties of grapefruit. Mutation breeding is considered a traditional breeding technique, and thus is not an “excluded method” for organic farming in the United States.
CRISPR for mutation is more similar to mutation breeding than it is to genetic engineering. It creates similar end products as mutation breeding, but removes the randomness. It does not introduce new DNA. It is a controlled and predictable technique for generating helpful new plant varieties capable of resisting disease or weathering adverse environmental conditions.
Opportunity lost – learning from genetic engineering
Most commercialized genetically engineered traits confer herbicide tolerance or insect resistance in corn, soybean or cotton. Yet many other engineered crops exist. While a few are grown in the field, most sit all but forgotten in dark corners of research labs because of the prohibitive expense of passing regulatory hurdles. If the regulatory climate and public perception allow it, crops with valuable traits like these could be produced by CRISPR and become common in our soils and on our tables.