It turns out that the U.S. Department of Agriculture (USDA) says that it doesn't need to regulate a genetically modified mushroom. The agency has said that the mushroom, which was changed with the gene-editing tool CRISPR-Cas9, doesn't qualify as something that the agency should regulate.

The mushroom is just one of 30 genetically modified organisms that have managed to not need the USDA's regulations in the past five years. With that said, once a crop passes the USDA reviews, it may still undergo a voluntary review by the U.S. Food and Drug Administration.

In this case, several of the plants that were bypassed by the USDA were created using gene-editing techniques that included zinc-finger nuclease and transcription activator-like effector nuclease systems. Now, it seems that the USDA is also giving a pass to some organisms engineered with CRISPR-Cas9.

The mushroom itself is genetically engineered to resist browning. Researchers effectively targeted the family of genes that encodes polyphenol oxidase (PPO), which is an enzyme that causes browning. The researchers knocked out just one of six PPO genes in order to reduce the enzyme's activity.

"The research community will be very happy with the news," said Caixia Gao, a plant biologist at the Chinese Academy of Science, who was not involved in creating the mushroom. "I am confident we'll see more gene-edited crops falling outside of regulatory authority."

So why wasn't the mushroom regulated? This is largely because the mushroom itself is just missing genes rather than possessing foreign DNA from other organisms, like viruses or bacteria. In fact, many new gene-editing techniques do not involve using DNA from other organisms, which means that fewer genetically modified organisms need to be regulated.

This isn't the only crop that has avoided USDA regulation. The past several years have seen other GMOs that have slipped past the USDA. This includes a potato that has had its genes knocked out that would potentially make French fries healthier. Additionally a new herbicide-resistant canola; a corn that would create less pollution from livestock waste; switch grass tailored for biofuel production; and even an ornamental plant that glows in the dark have slipped past USDA regulations recently.

In fact, these crops outline the fact that the USDA is allowing more and more crops to escape regulation due to new gene-editing techniques. Knocking out a gene, or making a tiny change in an existing gene, are both techniques that are now being used to genetically modify crops.

"Those are basically comparable to what you get from conventional breeding," said Neal Gutterson, vice president for agricultural biotechnology at DuPont Pioneer. "We certainly hope that the regulatory agencies recognize that and treat the products accordingly."