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ARS Home » Pacific West Area » Hilo, Hawaii » Daniel K. Inouye U.S. Pacific Basin Agricultural Research Center » Tropical Plant Genetic Resources and Disease Research » Research » Research Project #424486

Research Project: Pacific Tropical/Subtropical Fruit and Nut Genetic Resource Management and Sustainable Production Systems

Location: Tropical Plant Genetic Resources and Disease Research

2018 Annual Report


Objectives
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.


Approach
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 Report
This project has completed the designated five-year term and has been replaced by a new project, 2040-2100-016-00D, "Management, Characterization, and Evaluation of Pacific Tropical and Subtropical Fruit and Nut Genetic Resources and Associated Information". For additional information, see the report for the new project. This project is relevant to the NP301 Action Plan, Component 2: Crop Genetic and Genomic Resources and Information Management; Problem Statement 2B: Plant and Microbial genetic resource and information management, contributing to the NP 301 Action plan anticipated Products: Priority genetic resources and associated knowledge safeguarded in state-of-the-art genebanks and databases. Overall, all objectives have been met. Objective 1. Efficiently and effectively conserve, backup, regenerate and evaluate tropical/subtropical fruit and nut genetic resources and distribute samples and associated information worldwide. Over the entire project period, maintained thirteen designated clonal germplasm collections with over 1200 accessions representing sixty-one genus and 145 species in thirty-three acres of fields, six greenhouses and a tissue culture laboratory. Forty-five accessions of papaya and Vasconcellea have been regenerated, 6760 grams (gm) of seed, from Hilo, Paauilo, and Lalamilo fields. Forty-eight accessions of guava seed were collected (673 gm). In vitro back-up of breadfruit (20), Vasconcellea (11), pineapple (25), ginger (3) starfruit, litchi (2), macadamia (4), guava (3) and passiflora were initiated. Working closely with the USDA-ARS germplasm repository in Miami, Florida, transfer continued of the avocado to Hilo through Fort Detrick, Maryland, with eighty-one accessions successfully introduced. Working closely with the USDA-ARS, germplasm repositories in Puerto Rico and Miami, transfer of the cacao germplasm continued with fifty-six accessions introduced. Field trials of cacao are being established to evaluate select varieties. Observations have been collected for pineapple plant (9604), flower (2852) and fruit (3708), titratable acid (447), longan fruit (380), peach palm fruit (85), litchi fruit (5580), papaya fruit (450), breadfruit fruit (464), breadfruit plant (672), pili nut (1284), guava fruit (290), rambutan fruit (240), litchi and longan flower (462). Germplasm Resources Information Network (GRIN) Global allows researchers to search characterization records, accession and history information available globally within the National Plant Germplasm System (NPGS) and cooperators’ collections for specific traits. In GRIN Global, seventy-two cooperators, 279 orders, 2419 order items, sixty-seven accessions, 153 inventories, twelve narratives, 171 observations, thirty-nine pathological descriptors, 418 pathological new records were entered. Twenty-four environments, 7527 observations, seventeen accessions, and ninety-one inventory existing records were updated. Two hundred thirty-four requests were filled with 1929 items. Different propagation methods are being explored for breadfruit and once established will be used to expand our collection from the accessions at the National Tropical Botanical Garden, Kahanu, Maui. Tissue cultured pineapple plants are being tested for pineapple mealybug wilt viruses in preparation of being sent to the National Center for Genetic Resources Preservation (NLGRP) in Ft. Collins, Colorado, for development of cryogenic storage, seeds of eight papaya accessions have already been sent. Rejuvenation of guava, rambutan, and breadfruit plantings are substantially complete. Air-layers of older trees are field planted or potted for back-up. In addition, cacao, breadfruit, guava, macadamia, rambutan, litchi, longan, and starfruit are pruned for size control and to stimulate new growth. One thousand four hundred and thirty-five pineapples replanted. The Vasconcellea collection is rejuvenated, twelve accessions representing nine species were moved to a different greenhouse to avoid infection by various viruses. Peach palm planting was thinned of eighty trees to stimulate new growth from the roots of the old tall trees. We have also contributed to the multi-site NPGS tropical/subtropical genetic characterization program by working in cooperation with the curator at the Puerto Rico germplasm repository to place rare bananas from the Pacific and Hawaiian Islands into tissue culture for virus indexing and preservation. Morphological/molecular identification and/or etiology of more than 50 diseased samples from various germplasm crops, including avocado, guava, lychee, macadamia,rambutan and longan were determined and information on diagnosis and management was incorporated into the repository management program. Objective 2. To strategically expand and improve current tropical/subtropical fruit and nut germplasm collections through international exchanges. We introduced 65 plant accessions from the U.S. and 8 foreign accessions to the collection. We continue to work with USDA Animal and Plant Health Inspection Service (APHIS) and the Hawaii Department of Agriculture to update our protocols and provide current information to requestors of our germplasm material and ensure material is successfully delivered. Utilizing the collections at the University of Hawaii College of Tropical Agriculture and Human Resources (CTAHR) Waiakea and Kainaliu Experiment Stations, we have introduced new macadamia, and avocado accessions to our collection. Additional accessions have been received from local sources, Puerto Rico or the U.S. mainland. Accession information is being updated in GRIN-Global to enhance collaboration with international partners. Objective 3. To 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. We collected and provided descriptor data to researchers for development of genetic markers for our papaya (Carica)/Vasconcellea, longan (Dimocarpus), macadamia (Macadamia), rambutan and pulasan (Nephelium) and pineapple (Ananas) collections. This research has resulted in numerous publications on characterization of our pineapple and longan collection, as well as providing basic information on papaya sex linked genes. Objective 4. For the development of a ‘quarantine-safe’ germplasm transfer system modeled after the ongoing transfer and back-up of the NPGS avocado collection in Miami to the NPGS in Hilo. Laurel wilt and Avocado Sun-Blotch Viroid (ASBVd) are of economic importance for the common avocado. The Hilo germplasm repository is serving as a backup for Miami’s avocado collection. ASBVd and laurel wilt (Raffaelea lauricola) testing protocols were established at the NPGS-Hilo. Testing for ASBVd (RT-PCR) and laurel wilt (PCR) was performed on more than 200 samples from the Hilo quarantine shade house and field samples from Hawaii Island. Thus far, all samples on the repository and neighboring University of Hawaii at Manoa avocado fields are negative for both pathogens. Improved methods for ASBVd testing established by the Miami repository were adopted by the Hilo repository and has allowed for quicker transfer of material to Hilo.


Accomplishments
1. Preserving, distributing and expanding lines of tropical fruit and nut trees. ARS scientists in Hilo, Hawaii, collect, maintain, and distribute 13 designated tropical fruit and nut crop germplasm accessions in fields, greenhouses, and tissue culture. One macadamia, one peach palm (9 plants), one breadfruit, one new pili nut, one rambutan, and seven avocado accessions have been added to the collection. Forty requests for 359 items were filled. Requests included samples for genetic characterization studies for papaya and relatives, rambutan and relative, and macadamia, or for disease screening of pineapple. Foreign requests were filled for papaya seeds to Pakistan and guava seeds to Zimbabwe. This project contributed to positive economic and environmental impact worldwide by providing a reliable and sustainable resource of plant germplasm for research and crop production and provides critical plant genetic resources for fundamental knowledge in plant science.

2. Protecting avocado. Laurel wilt and Avocado Sun-Blotch Viroid (ASBVd) are of economic importance for the common avocado. ARS researchers in Hilo, Hawaii, have been worked collaboratively with ARS researchers in Miami, Florida, and Fort Detrick, Maryland, to develop a “quarantine-safe” germplasm transfer system to back-up the National Plant Germplasm System (NPGS) avocado collection in Miami. Avocado sunblotch viroid (ASBVd) and laurel wilt (Raffaelea lauricola) testing protocols were established at the Hilo repository and samples from neighboring University of Hawaii at Manoa avocado fields in Hilo and local avocado collection sites in Kona tested negative for both diseases. All avocado plants transferred from Miami to Hilo continually tested negative. This collaborative project safeguards avocado genetic resources and is a model for “quarantine-safe” transfer of plant germplasm in the U.S.


Review Publications
Vanburen, R., Man Wai, C., Zhang, J., Han, J., Arro, J., Lin, Z., Liao, Z., Yu, Q., Wang, M., Zee, F., Moore, R.C., Charlesworth, D., Ming, R. 2016. Extremely low nucleotide diversity in the X-linked region of papaya caused by a strong selective sweep. Genome Biology. 17:230.