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United States Department of Agriculture

Agricultural Research Service

Related Topics

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

2011 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.


3.Progress Report

Market Testing of Labeled versus Unlabeled GMO Papaya: In order to test consumer response to GM fruit, four California stores selected on income level of surrounding consumers were selected for a study of acceptance to genetically modified (GM) labeled fruit. In all locations, the labels “Hawaiian Grown GMO Papayas” were placed on the fruits along with a designated scan number versus non-labeled papayas. The two fruits, otherwise identical, were displayed and marketed next to each other and prices were the same for unlabeled vs. labeled papaya. Results indicate labeling decreased sales. Explicitly identifying the fruit as genetically modified increases market risk. Consumers appear to identify labeled fruit as lower quality or less safe, or lack knowledge regarding the term “GMO”. Labeling papaya in California is the opposite previously found for Hawaii consumers. The response in Japan markets remains to be ascertained. Genotyping Hawaiian Taro Varieties: Microsatellites have been developed within the taro genome from China and Oceania. In total, 52 polymorphic DNA sites have been located. The markers are used to screen for polymorphisms within the Hawaiian taro varieties. From the 11 polymorphic microsatellite loci reported from China, ten were amplified in the Hawaiian varieties. Analysis shows all loci are variable with an average of 5.25 alleles/locus. Genotypic characterization of native varieties will follow. SNP – Resistance to Taro Leaf Blight: Cross 1005 of two taro strains showed strong resistance to TLB using the excised-leaf disc assay. After two trials, 14.9% of the hybrids showed complete resistance. DNA is being extracted from both parents of 1005 and is undergoing SNP analysis. DNA from resistant and non-resistant progeny will undergo SNP analysis to determine genetic markers for this population.

Germplasm Storage of Taro: Culture contamination due to air conditioning renovations shifted objectives from studying manipulation of in in-vitro culture to study of culture recovery conditions. The new objectives were: to develop a monitoring system to monitor airborne contamination levels, determine whether contaminated cultures can be rescued under ex vitro conditions, develop an ex-vitro acclimatization protocol for rescued cultures, and to compare plantlet growth in agitated liquid suspension cultures vs. stationary liquid suspension cultures. The primary culture contaminant was penicillin. Air sampling suggests a correlation of particles >5m with contamination. Rescue study observations for 2 weeks post–transplanting showed no chlorotic or necrotic symptoms. A difference in growth rate between treatments was found. The best recovery medium was 100% vermiculite that had an average of 32% greater fresh weight than the 50% treatments after 1 and 2 weeks with a 16% increase in fresh weight if the culture was covered. Study indicated that the cover maintained average relative humidity 10% higher than without. A medium combination with 75% peat moss #2 mix produced the healthiest and largest plants after 6 months.

The project is monitored through meetings, telephone, and email communications.


Last Modified: 12/22/2014
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