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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

2017 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
Progress has been made on all four objectives of this project. Objective 1: Efficiently and effectively conserve, backup, regenerate and evaluate tropical/subtropical fruit and nut genetic resources and distribute samples and associated information worldwide. We maintain thirteen designated clonal germplasm collections with 1,022 accessions representing 61 genera and 145 species in 33 acres of fields, greenhouses and a tissue culture laboratory. We have 35 accessions of papaya (26 accessions planted in Hilo, 8 in Paauilo, 1 in Lalamilo) planted for seed regeneration. There were 286 papaya trees field planted. We harvested and stored 1,369 grams of papaya seed from fields and 156 grams (Vasconcellea sp.) from greenhouses, removed 853 grams of old seed from refrigerators and updated our inventory. The rejuvenation of our guava, rambutan, and breadfruit plantings are in progress, new trees are being air-layered and planted to replace old larger trees, with 6 trees being orchard planted. In addition; cacao, guava, starfruit, macadamia, rambutan and pulasan accessions were pruned for size control and to stimulate new growth and 104 pineapples were replanted. The peach palm orchard was thinned, removing 80 trees to stimulate new sprouts from the roots of the older tall trees. Younger, vigorously growing plants are often easier to maintain and record observations. As a backup to the field and greenhouse collections, pineapple (8), breadfruit (16), ginger (3), macadamia (4), and guava (3) accessions were initiated into tissue culture. The protocol to cryopreserve the pineapple (Ananas) collection has been successfully developed by our ARS collaborators at the National Laboratory for Genetic Resource Preservation (NLGRP), Fort Collins, Colorado. Plantlets are being grown and virus tested in Hilo before sending for cryopreservation. Papaya (Carica) and Vasconcellea seeds are also being prepared to send to NLGRP for cryopreservation. We continue to serve as a backup for the ARS germplasm repositories in Miami, Florida, and Mayaguez, Puerto Rico. This year, 7 new accessions of avocado were introduced to Hilo from Miami, Florida, through Fort Detrick, Maryland; scions were tested for both Avocado Sun Blotch Viroid and Laurel Wilt Disease in Miami, Fort Detrick and Hilo. Once cleared through the self-imposed quarantine, avocado accessions are maintained as duplicate plantings in the greenhouse in two gallon pots and in the field. This new protocol reduces the pot size from twenty- to two-gallon, therefore 48 accessions were grafted onto rootstock in the smaller pots. To date, 70 avocado accessions have been backed-up from the Miami collection to protect from Laurel Wilt Disease. Additional local avocado varieties have also been planted in the field as a source of rootstock material. Characterization and distribution of germplasm was recorded in the Germplasm Resources Information Network (GRIN) Global system which allows characterization/accession/history information to be available globally. Researchers are able to search the National Plant Germplasm System (NPGS) collections (and other cooperator’s collections) for specific traits. For our primary crops we entered 9 cooperators, 75 orders, 520 order items, 37 accessions, 42 inventory, 9 observations, 12 narrative, one environment and one voucher into GRIN. We collected observations on 9 pineapple fruit (198 observations), 133 pineapple flowers (532 observations), 23 pineapple plants (322 observations), 38 titratable acid, 7 litchi and longan flowers (462 observations), and 14 pili nut fruit harvest (84 observations). We filled 41 requests for 351 items. Three of those requests were to foreign researchers (13 macadamias to India, 12 papayas to Mexico and 119 pineapple leaf samples to China) and 5 requests were for molecular studies. Objective 2: Strategically expand and improve current tropical/subtropical fruit and nut germplasm collections through international exchanges. We introduced 19 accessions from the U.S. to our collection. We continue to update protocols and work with the USDA Animal and Plant Health Inspection Service to provide current information to requestors of our germplasm material and ensure material is successfully delivered to the requestors. Rooting of soft wood guava cuttings experiment is progressing. Propagation of breadfruit via cuttings is also progressing with positive results on several accessions. Objective 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. We provided samples and worked cooperatively to develop and publish molecular markers to characterize the pineapple collection. Objective 4: 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. Avocado plants transferred from Miami, Florida, to Hilo, Hawaii, continue to test negative for the presence of Laurel Wilt and Avocado Sun Blotch. Avocado Sun Blotch has also not been found in samples collected from avocado trees in Hilo and Kona, Hawaii. A sample was received from a homeowner who suspected Laurel Wilt but this sample was not found to contain the Raffaelea lauricola causal agent. We received training from personnel at the Miami repository to molecularly detect Avocado Sun Blotch, and are now able to test locally rather than collect material and send to Miami for testing.


Accomplishments
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 accessions. Over the last year, we collected over 1,598 observations on plants, flowers and fruits and distributed 351 propagules of plant material from our germplasm collections. We continue to collaborate and serve as a backup for the avocado (15 trees field planted) and cacao collections (16 field planted) in Miami, Florida, and Mayaguez, 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.