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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

2012 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:

The goal of this agreement is to carry out a collaborative research effort among PBARC, The College of Agriculture, Forestry and Natural Resource Management(CAFNRM) at the University of Hawaii at Hilo (UHH), and the College of Tropical Agriculture and Human Resources (CTAHR) at the University of Hawaii at Manoa (UHM) that addresses important agriculture problems in Hawaii which directly contributes to objectives 1 and 2 of the in-house project.

Three studies on taro and giant taro were conducted during the period 1 October 2011 to 30 September 2012. Additionally, a market study on GMO papaya was conducted in Japan before being terminated in January 2012. Unfortunately, because of the death of that investigator, the papaya report is unavailable.

Sustainable Giant Taro Production Under High Salinity in the Pacific: A cooperative TSTAR Project, “Sustainable Giant Taro Production Under High Salinity in the Pacific”, is evaluating salt tolerant giant swamp taro, Cyrtosperma, and giant taro, Alocasia, germplasm from American Samoa and Micronesia. This is of great potential interest as the freshwater lakes on these islands may become saline because of sea level rise. An alternative is to develop an artificial raised (elevated) lo’i system. A prototype was constructed and tested at the UH-Hilo farm. Two layers of 6 mil black plastic line the lo’i. The lo’i is only 4 feet wide so can be tended without stepping on the 6mil black plastic liner. This is wide enough to grow Cyrtosperma, the giant swamp taro. The present crop of taro in the raised artificial loi is now 8 months old and will be harvested and data recorded to estimate nutrient use and production.

Application of biotechnology to taro: Thirty microsatellite DNA markers reported to resolve taro varieties (Hu et al. 2009; Mace & Godwin 2002) were evaluated, and found that just 8 of these detected DNA polymorphisms among Hawaiian varieties. These markers were able to resolve many but not all of the Hawaiian varieties. However, they consistently resolved Hawaiian from non-Hawaiian varieties. We used RAD sequencing analysis to identify a large number of SNPs in taro, and we are in the process of genotyping Hawaiian taro and hybrid taro varieties using these SNPs. Further, we used a detached-leaf assay to screen taro crosses for resistance to P. colocasia. We determined that lesion size in this assay correlates with field susceptibility, and we have identified three parental lines that confer very good detached-leaf resistance. We have transferred those lines to field sites to evaluate them for field resistance.

Germplasm storage of Colocasia esculenta (taro): The effects of agitation and tomato extract treatment on germplasm storage of taro was investigated. There was no growth response difference between stationary and agitated liquid media. The tomato extract treatment produced twice as many leaves per plantlet (compared to the control) but it also produced the shortest leaves.


Last Modified: 12/20/2014
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