Alexander Trevi gets the dish from researcher and gardener Paige Johnson:
After WWII, there was a concerted effort to find 'peaceful' uses for atomic energy. One of the ideas was to bombard plants with radiation and produce lots of mutations, some of which, it was hoped, would lead to plants that bore more heavily or were disease or cold-resistant or just had unusual colors. The experiments were mostly conducted in giant gamma gardens on the grounds of national laboratories in the US but also in Europe and countries of the former USSR.
Johnson reveals that mint oil, present in chewing gum and toothpaste and the Rio Star grapefruit, which accounts for 75% of the grapefruit production in Texas, were both developed in gamma gardens and "the genetic change produced by irradiation remains in the commercially cultivated variety" today.