Genetically modified wheat has been discovered growing in a field in Oregon. GMO wheat is not approved for sale in the U.S. Above, a wheat field in Arkansas. Danny Johnston/AP hide caption

itoggle caption Danny Johnston/AP

Genetically modified to be enriched with beta-carotene, golden rice grains (left) are a deep yellow. At right, white rice grains. Isagani Serrano/International Rice Research Institute hide caption

itoggle caption Isagani Serrano/International Rice Research Institute

Soon after being sliced, a conventional Granny Smith apple (left) starts to brown, while a newly developed GM Granny Smith stays fresher looking. Courtesy of Okanagan Specialty Fruits Inc. hide caption

itoggle caption Courtesy of Okanagan Specialty Fruits Inc.