Richard Manshardt

Genetically engineered (GE) ringspot virus-resistant papaya cultivars ‘Rainbow’ and ‘SunUp’ have been grown in Hawai’i for over 10 years. In Hawai’i, the introduction of GE papayas into regions where non-GE cultivars are grown and where feral non-GE papayas exist have been accompanied with concerns associated with transgene flow. Of particular concern is the possibility of transgenic seeds being found in non-GE papaya fruits via cross-pollination. Development of high-throughput methods to reliably detect the adventitious presence of such transgenic material would benefit both the scientific and regulatory communities.

Dioecious papayas were introduced shortly after Cook’s 1778 discovery of Hawai’i but were supplanted for commercial uses by the gynodioecious solo papaya brought from the Caribbean in 1911. Growth of a local papaya industry based on hermaphrodite plants was enabled by research allowing prediction of seedling sex segregation and by development of cultivars with high quality, symmetrical fruits free of stamen carpellody, and carpel abortion. The industry expanded into export markets after 1940 by providing an alternative use for land and expertise abandoned by declining sugar plantations, adopting a cultivar capable of tolerating long-distance shipping, developing postharvest technology to overcome fruit fly quarantine restrictions, capitalizing on a growing tourism industry for marketing and air freight logistics, and forming an organization to support industry growth. In recent years, the industry has withstood pest and disease challenges by adopting innovative technologies that have allowed high-quality solo papayas to continue to participate in an increasingly competitive export market.