I don't know about the GMO apples!
The browning is caused by oxidation of Phenols compounds by an enzyme cald
polyphenol oxidase, when the Appel is cut, you can prevent the browning by covering the cuts by something acidic, like lemon, or vitamin c that have anti oxidation qualities! The gas that rapines the fruit is Called ethylene, and I dont see any connection between the 2!
I recommend you to put your fruit in a paper bag, with Granny smith apples or some Bananas I think it will do the trick!
You must remember that there is some kinds fruit that are not Calimetric and they wont rapines after being cut from the plant!