The U.S. is trying to figure out whether, and how, to regulate crops that have had their genes "edited." One example: a mushroom that doesn't brown when cut. It could be the first of many such crops.

The U.S. is trying to figure out whether, and how, to regulate crops that have had their genes "edited." One example: a mushroom that doesn't brown when cut. It could be the first of many such crops.