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 2040-21000-014-00, Pacific Tropical/Subtropical Fruit and Nut Genetic Resource Management and Sustainable Production Systems. Under objective one, we maintain 13 designated clonal germplasm collections with 1,003 accessions representing 61 genus and 145 species in 33 acres of fields, greenhouses and a tissue culture laboratory. We have 17 accessions of papaya (11 accessions planted in Hilo, five in Paauilo, one in Lalamilo) planted for seed regeneration. We harvested and stored 1,797 grams of papaya seed, removed 7,402 grams or 16.32 lbs of old seed from refrigerators and updated our inventory. We also collected and stored 700 grams of guava seed, removed old seed and updated 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. In addition, cacao, guava and starfruit accessions were pruned for size control and to stimulate new growth and 451 pineapples were replanted. Younger, vigorously growing plants are often easier to propagate for order requests. The Vasconcellea collection is being rejuvenated, 12 accessions, 160 plants, representing nine species were planted in a different greenhouse to avoid infection by various viruses. As a backup to the field and greenhouse collections, Vasconcellea (6), pineapple (8), breadfruit (4), ginger (3) and one litchi 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 Center for Genetic Resources Preservation, Fort Collins, Colorado. We also continue to serve as a backup for the ARS germplasm repositories in Miami, Florida, and Mayaguez, Puerto Rico. This year, 17 new accessions of avocado were introduced to Hilo from Miami, Florida, through Fort Detrick, Maryland, after 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 20 gallon pots and in the field. To date, 45 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. In addition, 19 accessions of cacao were introduced from the Puerto Rico germplasm repository as backup and for local cacao field trials. 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 26 cooperator, 44 orders, 640 order items, and 25 accessions into GRIN. We collected observations on 66 pineapple fruit (1,452 observations), 173 pineapple flowers (692 observations), 178 pineapple plants (2,492 observations), 119 titratable acid, four breadfruit accessions (320 observations), six breadfruit plants (630 observations), two pili nut accessions (600 observations), rambutan fruit (240 observations), and longan fruit (190 observations). We filled 56 requests for 230 items. Objective 2. To strategically expand and improve current tropical/subtropical fruit and nut germplasm collections through international exchanges, we have introduced four accessions from the U.S. and five foreign accessions to our collection. We continue to update protocols and work with the USDA Animal and Plant Health Inspection Service (APHIS) to provide current information to requestors of our germplasm material and ensure material is successfully delivered to the requestors. Objective 3. To strengthen our genetic marker analytical capacity to minimize inefficiencies in sample handling, we worked cooperatively to develop and publish molecular markers to characterize the pineapple collection. We have also contributed to the multi-site NPGS tropical/subtropical genetic characterization program by working in cooperation with the curator at the Mayaguez, Puerto Rico germplasm repository to place rare bananas from the Pacific and Hawaiian islands into tissue culture for virus indexing and preservation. Objective 4. 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. We are working with personnel at the Miami repository to cross train technicians on a more sensitive protocol for detection of Avocado Sun Blotch.
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 6,600 observations on plants, flowers and fruits and distributed 230 propagules of plant material from our germplasm collections. We continue to collaborate and serve as a backup for the avocado and cacao collections 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.
2. Molecular characterization of pineapple (Ananas) collection. Pineapple (Ananas) represents the third most important tropical crop after banana and mango. ARS scientists in Hilo, Hawaii, and Beltsville, Maryland, collaborated on developing single nucleotide polymorphism (SNP) markers to characterize the pineapple collection. These SNP markers provide a robust and universal method to characterize pineapple accession and are important in determining the diversity of the collection. Information from this study will improve the efficiency of the repository by identifying potential redundancies and gaps to help prioritize future collections. The markers will also serve as a foundation to identify new genes to assist pineapple breeding and evaluation for important agricultural traits.
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