Two varieties of apples that have been genetically engineered not to turn brown when cut or bruised were cleared in February and March of 2015 for growth and sale in Canada by the Canadian Food Inspection Agency (CFIA) and Health Canada (HC) and in the United States by the U. S. Department of Agriculture (USDA) and U.S. Food and Drug Administration (FDA). See also: Apple; Genetic engineering; Genetically engineered plants; Genetically modified crops

The two varieties—Arctic^® Golden and Arctic^® Granny—are genetically modified versions of Golden Delicious and Granny Smith apples developed, grown, and tested for safety over an 18-year period by Okanagan Specialty Fruits of Canada.

When an apple is cut or bruised, damaged cells release phenolic compounds that react with oxygen to form quinones in the presence of the enzyme polyphenol oxidase (PPO). The quinones then react with each other to form brown pigments, called melanin, which are visible as browning. Oxidized or browned apples may be aesthetically unpleasing and may have a slightly altered taste, but they are safe to eat and should not be confused with decomposed, rotten apples. See also: Enzyme; Phenol; Pigmentation; Quinone

To suppress the browning reaction, a cellular process known as gene silencing or RNA interference (RNAi) is used to “turn off” the genes that produce PPO. Additional copies of apple PPO genes (transgenes) are inserted into the genomes (DNA) of Arctic^® apples. When the transgenes become active, the RNA they produce forms double-stranded molecules (ds-RNA), which in turn trigger cellular defenses that evolved to thwart viruses. Enzymatic mechanisms then destroy not only the RNA from the transgenes but also the RNA from the apple’s original PPO genes, thereby blocking all PPO production. See also: Deoxyribonucleic acid (DNA); Gene; Gene silencing; Ribonucleic acid (RNA); RNA interference

For now, Canadian and U.S. regulators have accepted nonbrowning apples as safe. Whether or not apple growers or consumers will accept genetically modified apples and whether any unforeseen risks emerge is to be seen. However, Okanagan Specialty Fruits does not plan to label these apples as genetically modified, perhaps to avoid bruising their reputation in the marketplace.