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United States Department of Agriculture

Agricultural Research Service

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Research Project: Research on Papaya to Be Exported to Japan and Characterization and Preservation of Hawaiian Taro Cultivars

Location: Tropical Plant Genetic Resources and Disease Research

2010 Annual Report


1a.Objectives (from AD-416)
The genetically engineered papaya has been commercialized in Hawaii since 1998 and now is close to being deregulated in Japan, which will allow the export of genetically engineered papaya to Japan in 2010. The exportation of the transgenic papaya is being headed by the Hawaii Papaya Industry Association (HPIA). With taro, controversy over genetic engineering has occurred, with a significant part involving cultural aspect of Hawaiian taro as it relates to the Hawaiian race. The objectives of this proposal are to.
1)To assess the impact labeling and marketing strategies that are deployed by HPIA on the commercialization of the transgenic papaya in Japan, and.
2)further characterize the native Hawaiian taro cultivars using molecular markers, and to develop genetic maps of six Hawaiian taro varieties and two ex-Hawaii strains.


1b.Approach (from AD-416)
Transgenic papaya: A close collaborative effort will be made with HPIA as it markets the transgenic papaya in Japan. A sample of grocery stores in Japan will be used to study the impact of labeling on sales of transgenic papaya. The sales of GM and nonGMO papaya will be monitored and recorded. It is anticipated that the research objective will be completed within the first two years of introduction of the transgenic papaya to Japan. Hawaiian taro: Efforts will be made at collecting, cloning, and storing the taro germplasm at UH Hilo under tissue culture conditions in order to lower the costly maintenance of taro under field conditions. Available microsatellite markers will be used in differentiating the Hawaiian varieties. Pyrosequencing will be done of selected cultivars to provide the rapid acquisition of very large volumes of DNA sequence information, which will be used in nucleotide polymorphism to identify the taro cultivars. Documents SCA with U of HI. Formerly 5320-21000-011-05S (9/09).


3.Progress Report

The agreement was established in support of the Objective of the in-house project to develop new knowledge of the genetics, genomics, and transgenics of selected tropical crops.

Research on transgenic papaya to be exported to Japan: The Puna area produces the great majority of Hawaiian papaya, and an outbreak of papaya ringspot virus (PRSV) in 1993 almost eliminated this industry. The development and deployment of genetically-engineered transgenic papaya with resistance to PRSV allowed papaya cultivation to continue in subsequent years, even as PRSV persists in the environment.

Currently, over 80% of Hawaiian-grown papaya carries transgenic resistance to PRSV. This has allowed the industry to remain commercially viable, but Japan represented a significant portion of the papaya market and the Japanese government has not permitted the importation of transgenic papaya for public consumption.

A study was designed to test consumer acceptance of transgenic, or genetically modified (GM) papaya in Hawaii as preparation for a future study to evaluate consumer acceptance of GM papaya by Japanese consumers. Chain grocery stores in Honolulu were invited to sell papaya labeled with their GM status alongside unlabeled fruit. Data is currently being collected.

Characterization and preservation of Hawaiian taro cultivars: Taro has great cultural significance for the Hawaiian people. Hawaiian taro cultivars are differentiated using many morphological characteristics, and hybrids between varieties blend these characteristics. Thus, a DNA-based test is needed to identify and catalog the archival Hawaiian varieties, and to aid in future breeding efforts. We evaluated a DNA microsatellite method that can differentiate taro varieties collected from different continents. This method was able to differentiate many, but not all of the Hawaiian varieties. We looked at 60 Hawaiian varieties, 3 Palauan varieties as well as a number of hybrids, and found unique patterns for 11 Hawaiian varieties (the other 49 were too closely related to individually resolve, and resolved into groups). However, Palauan varieties were clearly distinguishable from Hawaiian varieties.

We are also evaluating methods for the in vitro propagation and maintenance of Hawaiian taro varieties. This has resulted in an effective disinfestation and propagation regime. Standard plant tissue culture media supplemented with plant hormones are sufficient for establishment, multiplication and maintenance of Hawaiian taro varieties. Liquid medium resulted in faster growth than solid medium. One of our goals is to develop a protocol for long-term maintenance that would minimize required transfers. Thus, a commercial liquid compost product was an effective additive for initial culture, but not for long-term plant maintenance. Our recent work shows that once the cultures are established, reducing the nutrient concentration in the culture medium can greatly extend the time between required transfers.

The project is monitored via meetings, site visits, progress reports, and email and telephone communications.


Last Modified: 7/22/2014
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