Scientists successfully created two virus-resistant varieties of papaya: SunUp and Rainbow. SunUp had reddish-flesh fruit and two copies of the coat protein (cp) gene. Rainbow, which had yellow-flesh fruit and only one copy of the coat protein (cp) gene, was a hybrid of SunUp and a popular non-transgenic variety.
In what turned out to be serendipitous timing, PRSV-resistant transgenic papayas were being field-tested just as the Puna region papaya plantations were being decimated by PRSV in the early 1990s. Despite the positive results in the early field trials, some farmers initially were pessimistic about the potential of the transgenic fruit. Their doubt was understandable, of course, given that their livelihoods were at stake. > Step 3: Getting Approval to Grow "What we had done through the field trial would only be academic unless the papaya got through the red zone of translational biotechnology… getting the papaya deregulated and commercialized." ~ Dennis Gonsalves
Although the experiments indicated that the transgenic papayas were resistant to PRSV, the plants could not be used commercially until they were approved by regulatory agencies. The virus protein coat gene inserted into the papaya genome is considered a pesticide because it acts against a pest, the virus. So the Environmental Protection Agency (EPA) and the US Department of Agriculture (USDA) had to consider the transgenic organism's environmental and agricultural safety. The two agencies granted approval. Another regulatory agency, the Food and Drug Administration (FDA), considers food safety. It also granted approval, deeming the transgenic papaya safe for consumption since PRSV breaks down quickly in the human stomach
. In 1998, after researchers got the licenses to commercialize the transgenic papaya, the seeds for the transgenic papayas were distributed for free to growers.
Once the regulatory hurdles were cleared, farmers in Puna quickly accepted and started growing the transgenic papaya. They were delighted to have virus-resistant plants that produced good yields. Hawaiian transgenic papayas are sold in the United States as well as in Canada, Hong Kong, and Japan.