The USDA has decided to not regulate mushrooms that have been genetically modified using CRISPR-Cas9, making it the first CRISPR-edited crop that will be able to bypass the USDA’s regulations. It is the latest crop created with gene-editing techniques to not require USDA approval because it does not contain “plant pest” DNA. In fall 2015, a white button mushroom was genetically modified to defy turning brown over time by Pennsylvania State University plant pathologist Yinong Yang, who deleted a single polyphenol oxidase (PPO)–encoding genome to achieve the nonbrowning effect. As PPO enzymes are responsible for browning, the deletion of one of six PPO genes in the mushroom showed a 30% decrease in the enzyme’s activity. Source: Nature