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World Changing Ideas

What Does The New CRISPR-Edited Mushroom Mean For Agriculture?

You'll soon be eating gene-edited food and you might not even know it.

What Does The New CRISPR-Edited Mushroom Mean For Agriculture?

Photo: Yang Lab

The mushrooms of the future may last a little longer on the shelf, and a certain type of corn will have better yields. The white button mushroom and waxy corn were the first foods edited with CRISPR-Cas9—a gene-editing technique—to get a pass from the USDA: the agency won't regulate them before they can be sold.

CRISPR makes it simple to target a gene and delete it, or paste in another. By snipping a gene out of the mushroom's genome, a researcher from Penn State was able to develop a new variety with less activity from the enzyme that makes white mushrooms turn brown if they're cut.

Penn State—the only university that still has mushroom professors—was approached by the CEO of a mushroom company, who was worried about the problem of browning, which causes food waste both in the industry and when consumers take mushrooms home.

"When the industry is picking mushrooms, they have to handle them very carefully," says Yinong Yang, the plant pathologist at Penn State who developed the mushroom. "Even for retail—let's say, those sliced mushrooms—it will help, because even after a few days, when they are still good, they start browning."

Yang points out the mushroom will eventually brown—it's an "anti-browning" mushroom, but it still does change color after time. "We reduced the enzyme activity by 30% or a little more," he says. "You need more to keep it white. But you can't eliminate all enzyme activity, because that is not necessarily good ... if you totally eliminate it, you might have detrimental effects, like the mushroom may not grow well, or may be susceptible to pathogens, things like that."

The common white button mushroom, which is produced mainly in Pennsylvania, was actually cultivated after a mushroom farmer in the 1920s discovered some all-white mushrooms in his mushroom bed. In other words, it was a chance mutation that happened to reduce enzyme activity.

The new version of the mushroom is functionally no different than something that might have also mutated naturally. But CRISPR made the change simpler. "It would be hard to find this kind of mutation, because the mutation on the surface is a little easier to spot," Yang says. "For this one, you'd have to cut thousands of these mushrooms, and you probably won't find it."

When Yang sent a letter of inquiry to the USDA about the new mushroom, after several months, they replied that the mushroom wouldn't fall under their scope of regulating genetically modified foods. That's because the agency uses a peculiar test: If a new food is made with a "plant pest" such as bacteria or a virus, then the USDA has oversight under the Plant Protection Act of 2000. When the U.S. first developed its regulatory framework, most GMOs used the so-called plant pests in production. Now, they don't—so the law doesn't apply. The FDA doesn't evaluate plants for safety (it's up to the producer not to put something unsafe on the market).

The new waxy corn, which is being developed by DuPont Pioneer and may be in fields in five years, got a pass a few days after the mushroom under the same reasoning—no "plant pests" were involved. Waxy corn is better at making starch, both for food and for adhesives, than typical corn, but it usually has poorer yields. The new version can improve the yield to match other types of corn.

The Plant Protection Act was first developed to prevent plant pests or weeds from spreading, not GMOs. For regulators, in the beginning, it happened to be a way to squeeze GMOs into the purview of the USDA. But it was an artificial construct: If a company used Agrobacterium, a common bacteria used in genetic engineering in the past (and a so-called plant pest), it might have to spend millions to get through the regulatory process. Others, who used a "gene gun" instead to alter a plant, would not have been regulated at all. The same is true for modern techniques like CRISPR.

"It really was artificial—it didn't really trigger on whether there was additional risk or unique risks associated with a genetically engineered crop. It was the process used to transform the thing," says Alison van Eenennaam, a cooperative extension specialist and expert on genetic engineering from the University of California-Davis.

Now, the USDA is fundamentally reconsidering how it regulates GMOs, and considering making its authority greater—possibly encompassing even older techniques, like mutagenesis, that have never been regulated in the past.

But should the USDA be regulating a mushroom that's genetically identical to something that could have appeared through a natural mutation? The well-documented public fear of GMOs isn't backed up by science. And CRISPR has the potential to help solve a long list of problems in feeding the world.

CRISPR-edited crops could resist drought, fight plant diseases, and, like the new corn, improve yields. Other foods, like CRISPR-edited lean pork developed by researchers, could be healthier or avoid overused antibiotics. If regulation on CRISPR foods follows the same path as some GMOs, we could be waiting a long time to eat it; the first genetically engineered salmon took two decades to get approval. In the meantime, the world population is growing, and agriculture can't keep up.

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