Gene-Edited Plants and Animals: Can They Bridge the Divide in the GMO Debate?
By Abby Dilk
The debate surrounding genetically engineered (“GE” or “GMO”) plants and animals has historically been, and still is, extremely divisive. Anti-GMO activists raise many objections, including two that often resonate with a segment of the public: (1) control of the food supply by a few multinational corporations, and (2) reliance on pesticides.
To exemplify these controversies, take Bt corn and cotton, wherein scientists have introduced bacterial genes that produce insecticidal toxins. When insects eat portions of these plants where the toxin is produced—such as in the root, as is the case for the corn rootworm—they die, leaving the plant unharmed. Genetic engineering has also produced crops that are tolerant to glyphosate, so that when the herbicide is sprayed, the weeds around the plant are killed but the plant isn’t damaged. These GE crops have been developed by multinational companies and widely adopted by farmers in the U.S. and other countries.
But what if modern biotechnology could take those two objections out of the debate, as well as directly benefit consumers? Would there be greater consumer acceptance? A new generation of agricultural products that are being created through gene-editing techniques, such as CRISPR and TALENS, certainly have the potential to accomplish that. Both allow scientists to precisely delete or insert portions of DNA in the genome of a crop or animal. Gene editing is cheaper and easier to use than genetic engineering, so academic scientists and new startup biotechnology companies, in addition to multinational corporations, have begun to use these technologies to make new varieties of crops and animals with useful traits. Many gene-edited products in the commercial pipeline are not linked to pesticides and have unique traits that could be of interest to consumers. Here are a few examples:
Calyxt, a startup biotechnology company, has developed gene-edited high-oleic soybeans that the company says produce oil with 80 percent oleic acid content, compared to roughly 20 percent in conventional soybean oil. TALENs were used to edit four alleles that are responsible for converting oleic acid (an omega-9 fatty acid) into linoleic acid (an omega-6 fatty acid).
Calyxt estimates that the improved oil is more than five times less likely to go rancid, which makes it a good substitute for partially hydrogenated oils that were once widely used to both fry foods and extend the shelf life of processed foods. Partially hydrogenated oils are no longer “generally recognized as safe” by the U.S. Food and Drug Administration after the artificial trans fat in these oils was found to increase the risk cardiovascular disease. In response, many food companies have replaced partially hydrogenated oil with palm oil. But palm oil has more saturated fat than lard and also raises LDL cholesterol. So Americans’ hearts are still at increased risk. If the Calyxt high-oleic soybean oil replaces palm oil, that might improve the public’s health.
Penn State researchers report that they have produced a gene-edited mushroom that is purportedly somewhat resistant to browning. By using CRISPR to delete a handful of DNA base pairs from one of the six genes that encode for a browning enzyme, the researchers were able to reduce the enzyme’s activity by about 30 percent. That could greatly improve the shelf life of white button mushrooms and could mean less food waste and more money in consumers’ pockets.
Hornless Dairy Cows
Dehorning—mechanical removal of horns from cows—can prevent injuries to both farmers and other cows. The practice has long been decried by animal activists for the pain it causes. PETA (People for the Ethical Treatment of Animals) has a suggestion to eliminate it: breed naturally hornless cows.
Angus cows are naturally hornless, but it would take decades to naturally breed that trait into dairy cows. What if the gene that confers the trait could instead be replicated in dairy cows? Recombinetics, a privately held biotechnology company, claims to have successfully done that by using TALENs to delete 10 DNA base pairs and insert 212 DNA base pairs. The result: a “hornless” cow. If widely adopted, it could largely eliminate the need for dehorning.
Naturally Castrated Pigs
Castration is routinely performed to prevent an unpleasant pork odor and taste called boar taint, which is caused by hormones in post-pubertal pigs. Castration is typically performed on piglets in their first three days of life using a knife and no anesthesia. But Recombinetics claims to have used gene editing to silence a gene to prevent sexual maturation of the testes. That keeps the male pigs in a pre-pubertal state and eliminates the need to castrate them.
Tomatoes Resistant to Powdery Mildew
Using CRISPR, researchers in Europe and China have successfully created the Tomelo, a gene-edited tomato that is reportedly resistant to powdery mildew fungus (Oidium neolycopersici). The researchers deleted 48 DNA base pairs within the gene that confers most of the tomato plant’s susceptibility to the fungus. Powdery mildew causes tomato leaves to develop white spots, resulting in significant losses in yield. Fungicides are used to treat the mildew, including lime sulfur and a Bordeaux mixture (copper sulfate with lime), which are used in organic agriculture. According to the researchers, these fungicides would no longer be needed to treat tomatoes afflicted by this strain of powdery mildew fungus with the CRISPR Tomelo.
Barriers to the Gene-Editing Boom
Despite the potential benefits of these novel products, will they flourish in the U.S. and beyond? Before reaching the marketplace, they must be deemed safe by the federal government and must comply with any regulatory requirements. The U.S. Department of Agriculture recently stated that it “does not regulate or have any plans to regulate,” plants created through a variety of gene-edited techniques that do not involve the use of plant pests. On the other hand, the FDA tentatively asserted its authority to regulate gene-edited animals as “animal drugs,” though its draft guidance has not yet been finalized.
There are also concerns over intellectual property rights that need to be sorted out; it is unclear if CRISPR and TALENs will be licensed to more users than was the case for genetic engineering techniques. Most importantly, will farmers, chefs, food manufacturers, grocery stores, and others adopt these products, and will consumers buy them? If they get to market and consumers recognize the benefits they provide, then gene-edited crops and animals could be the spark to bridge the divide in the GMO debate.
 To create genetically engineered crops and animals, scientists typically remove a gene from one organism and randomly introduce it into another.
 Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) are short segments of repeated DNA sequences and Transcription Activator-Like Effector Nucleases (TALENs) are restriction enzymes. Both allow for very specific and precise changes to DNA. CRISPR and TALENs are naturally occurring in bacteria as part of their defense systems. Gene editing can produce crops and animals similar to “GMOs” through the addition of a foreign gene or it can merely edit the organism’s existing genes.
Contact Jeff Cronin (jcronin[at]cspinet.org) or Henry Duong (hduong[at]cspinet.org).