Objectives of this research project are:(1) Efficiently and effectively conserve, backup, regenerate and evaluate tropical/subtropical fruit and nut genetic resources and distribute samples and associated information worldwide; (2) Strategically expand and improve current tropical/subtropical fruit and nut germplasm collections through international exchanges; (3) Strengthen the genebank’s genetic marker analytical capacity to minimize inefficiencies in sample handling and to contribute more extensively to the multi-site NPGS tropical/subtropical crop genetic characterization program; and (4) Develop a “quarantine-safe” germplasm transfer system modeled after the ongoing transfer and back-up of the NPGS avocado collection in Miami to the NPGS genebank in Hilo as a means of protecting it from laurel wilt disease.
1) The curator and five staff continue management of the 14 designated clonal germplasm collections (app 1000 accessions) in 33 field acres, greenhouse & a tissue culture laboratory. C. papaya and Vasconcellea spp. seeds are regenerated every 4 years in PRSV-free fields and in greenhouses using controlled pollination. Cleaned seeds are stored at 4 C and storage units monitored electronically via a security company. A senior staff and the curator are on call for temperature alarm calls. Descriptors will be collected on plant and fruit morphologies and stored in a local database. Passport, inventory and descriptors information are periodically loaded onto the Germplasm Resource Information Network (GRIN). Survey of existing U.S. collections of tropical fruit genetic resources will be conducted; (2) Curator and scientists will work with Tropical/Subtropical Crop Germplasm Committee (CGC) members and the Plant Exchange Office to identify and collect germplasm already in the U.S. from University research collections and botanical gardens. Unit scientists will cultivate and establish working relationships with scientists in some Pacific Rim countries including the Philippines, Oceania, Vietnam and Thailand through participation in international germplasm conferences and meetings to identify potential resources of Sapindaceae (Litchi and rambutan relatives), Burseraceae (Canarium or pili nut relatives) and Moraceae (Artocarpus or breadfruit relatives). Information on NPGS germplasm policies, quarantine procedures and standard Material Transfer Agreements (MTA) will be collated and made available to cooperators to facilitate and encourage germplasm exchanges; (3) The research horticulturist will work with ARS scientists in Florida, Puerto Rico, and Mississippi to develop and apply SSR or SNP molecular marker technology for Litchi sp. (litchi), Ananas sp. (pineapple), Carica sp. (papaya), and related species (Vasconcellea and Jacaratia). Crop specific markers will be input into GRIN-Global with links to genetic observations. Thirty SSR molecular markers have been developed for Carica and will be compared to the newly developed SNP markers; and (4) The Hilo unit will follow a strict process in moving disease-free scionwood, after a designated quarantine period of visual inspection and testing for laurel wilt and ASBVd, from the Fort Detrick, MD quarantine facility to establish a NPGS avocado germplasm back-up in Hawaii. The scion will be grafted in Hilo onto clean rootstocks and confined in a quarantine facility for 4 to 6 months under supervision of the unit plant pathologist. Plants free from Laurel Wilt and ASBVd will be moved to a holding greenhouse for additional observations for four to six months before transplanting into larger containers and placing on elevated benches in the avocado germplasm screenhouse. Scion will be harvested from the germplasm collection for distribution or evaluation research.
Progress has been made on all four objectives of this project. Objective 1: We maintain 13 designated clonal germplasm collections with 1,028 accessions representing 61 genus and 145 species in 33 acres of fields, greenhouses and a tissue culture laboratory. We have 16 accessions of papaya for regeneration planted in the field, we harvested and stored 3581 grams of papaya seed from 20 accessions. We collected and stored 400 grams of guava seed (44 accessions). To create a clonal backup of the field collection, Artocarpus (5), Vasconcellea (5), Ananas (9), one Camellia, one Averrhoa, one Litchi and one Passiflora accessions were initiated into tissue culture. Working closely with the USDA, ARS tropical germplasm repositories in Miami and Puerto Rico, we are continuing transfer of the USDA National Plant Germplasm System (NPGS) avocado germplasm from Miami to Hilo through Fort Detrick, with 20 accessions coming in this year. We continue to serve as a backup for the core Theobroma cacao collection and introduced 10 accessions within this year. Preservation of the collection is the first part of the equation, then there is the task of characterization of the collections to link physical traits to genes, and identifying traits of interest. For the first time, the Germplasm Resources Information Network (GRIN) system allows researchers to search characterization records, accession and history information available globally within the NPGS system collections (and other cooperator’s collections) for specific traits. We entered 13 photos, 11 cooperators, 21 orders, 102 order items, 2 accessions, updated 23 environments, and 7527 observations in GRIN. We collected observations on 63 pineapple fruit (1386 observations), 246 pineapple flowers (984 observations), 178 pineapple plants (2492 observations), 9 breadfruit (144 observations), 2 breadfruit plants (42 observations), 2 papaya fruit (300 observations), 2 pili nut (600 observations), 2 guava (290 observations). We filled 57 requests for 654 items. Included in the requests were samples sent for genetic characterization for our longan collection (44), rambutan and pulasan (102), and pineapple (177 and 97 samples to two researchers) and 37 papaya and Vasconcellea samples. Objective 2: We added 45 accessions to the collection, three from Malaysia. Following Hawaii Department of Agriculture guidelines to import restricted species into the state, 10 new accessions were added to revitalize our Passiflora collection that was decimated by virus. We implemented a self-quarantine system for the Passiflora germplasm by placing new introductions directly into tissue culture. Once the quarantine period is complete and plants are tested for virus, the plants will be grown in the greenhouse for observations and collection of new seeds for cuttings for requests. The original plants will remain in culture to protect them from viruses and other disease and contain accession with weedy characteristics. Two accessions of breadfruit were acquired with one being a re-introduction and the other a new accession. We also received, 8 Ecuadorian cacao clones from Puerto Rico, 2 accessions from Hawaii Agriculture Research Center (HARC) and 20 avocado from Miami through Fort Detrick. Objective 3: We sent materials to three researchers for development of genetic markers for our papaya (Carica)/Vasconcellea, longan (Dimocarpus), rambutan and pulasan Nephelium and pineapple (Ananas) collections. The samples are being used to molecularly characterize the genetic diversity and identify potential gaps in the collection. Objective 4: All avocado plants received from Fort Detrick have been tested for Laurel Wilt and with no evidence of the pathogen detected. Laurel Wilt pathogen was not found in a survey of avocado plants around the Waiakea station in Hilo. We are working with ARS researchers in Miami to screen the plants for the Avocado Sun Blotch Viroid before plants are released from quarantine.
1. Preserving and distributing tropical fruit and nut trees. ARS scientists in Hilo, Hawaii, collect, maintain and distribute 13 designated tropical fruit and nut crop germplasm accesions. Over the last year, we collected over 6,000 observations on plant, flowers and fruits and distributed plant material for 654 requests from our germplasm collections. We continue to collaborate and serve as a backup for the avocado and cacao collections in Miami and Puerto Rico. The project contributes to positive economic and environmental impact worldwide by providing a reliable and sustainable resource of plant germplasm for research and crop production.
2. Characterizing tropical fruit and nut germplasm. Molecular evaluation of the genetic resource is important in determining the diversity of the collection. The same plant may have different varietal names in the different region that it is grown. ARS scientists in Hilo, Hawaii, have conducted preliminary molecular analysis of the breadfruit (Artocarpus), guava (Psidium) and longan (Dimocarpus) collection at the repository in Hilo. This will be the foundation to identify potential redundancies and gaps to prioritize future collection of germplasm accessions.
Hummer, K.E., Durst, R., Zee, F.T. 2013. Phytochemicals in fruits of Hawaiian wild cranberry relatives. Journal of the Science of Food and Agriculture. doi: 10.1002/jsfa.6453.
Sitther, V., Zhang, D., Harris, D., Zee, F.T., Yadav, A., Meinhardt, L.W., Dhekney, S. 2014. Genetic characterization of guava (psidium guajava l.) Germplasm in the United States using microsatellite markers. Genetic Resources and Crop Evolution. DOI: 10.1007/s10722-014-0078-5.
Wang, B., Tan, H., Fang, W., Meinhardt, L.W., Mischke, B.S., Matsumoto Brower, T.K., Zhang, D. 2015. Developing Single Nucleotide Polymorphism (SNP) markers from transcriptome sequences for the identification of longan (Dimocarpus longan) germplasm. Horticulture Research. DOI:10.1038/hortres.2014.65.
Zerega, N., Wiesner-Hanks, T., Ragone, D., Irish, B.M., Scheffler, B.E., Simpson, S.A., Zee, F.T. 2015. Diversity of the breadfruit complex (Artocarpus, Moraceae): Genetic characterization of critical germplasm. Tree Genetics and Genomes. doi: 10.1007/s11295-014-0824-z.
Keith, L.M., Matsumoto Brower, T.K., Suzuki, J.Y., Follett, P.A., Zee, F.T. 2015. Screening for powdery mildew resistance in ohelo berry germplasm in Hawaii. Pacific Agriculture and Natural Resources. 1:1-9.