2013 Annual Report
This has been an extremely productive project in terms of obtaining deregulation of the transgenic “Rainbow” papaya for shipment to Japan. All technical steps and necessary paperwork was also completed for consideration by China for import of “Rainbow.” As previously reported, significant advances were also made in analysis of transgenic papaya line 63-1. Transgenic line 63-1 is resistant to papaya ringspot virus (PRSV) and was deregulated by the Animal and Plant Health Inspection Service (APHIS) and the Environmental Protection Agency (EPA), but was not further pursued for commercialization because it had large segments of vector sequences. However, it has two coat protein transgenes and thus is an attractive model for basic studies to explore the impact that these coat protein transgenes would have on resistance to papaya ringspot virus. Border sequences were obtained and deep sequencing of the transgenic papaya genome is progressing. A further objective of this project was to develop transgenic papaya with less fruit blemishes. Fruits of the blemish free papaya (presumably ‘Golden Sunrise’) were obtained from a market in California and seeds of the fruit were grown on the Hamakua coast of Hawaii; this line was designated N08-75. Fruit from those plants showed similar characteristics to the commercial variety and indeed were blemish free. The trees were self pollinated and harvested seeds were also grown in the Waiakea region of the Hawaii island that resemble the ‘lava’ type of soil and moisture conditions of Puna, where 90 percent of Hawaii’s papaya are grown. The resulting fruit of these trees were also free of freckles. To incorporate PRSV-resistance to the line, the freckle free line was crossed with ‘SunUp’, which is a PRSV-resistant transgenic cultivar that was derived by transforming a nontransgenic ‘Sunset’, a sibling line to ‘Sunrise’. Recipricol crosses were made using ‘SunUp’ and N08-75 and seeds of the cross have been planted out in Waiakea and also in Puna at a commercial papaya farm. In the current year, protocols were developed to evaluate the impact of post-harvest handling on quality of the fruit, when it is ready for harvest.