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If you snip a bit of DNA from a vegetable, but add no new genes, does that vegetable qualify as a genetically modified organism, or GMO?
It's a hot question for government regulators, and it's no longer theoretical. Yinong Yang, a researcher at Penn State University, used a popular gene editing tool called CRISPR/Cas9 to snip out a tiny piece of DNA from one particular gene in a white button mushroom. This disables the gene, which in turn reduces the mushroom's production of an enzyme called polyphenol oxidase. As a result, the mushroom doesn't turn brown so quickly.
This may sound familiar. Scientists have also created non-browning versions of apples and potatoes. But those crops were considered GMOs, because scientists inserted new, slightly altered genes into those plants in order to "silence" the natural gene.
Last fall, Yang sent a letter to the U.S. Department of Agriculture, asking if his mushroom would be subject to regulation by the USDA. This week, the USDA sent its answer: No.