Location: Floral and Nursery Plants Research2012 Annual Report
1a. Objectives (from AD-416):
1) Strategically expand and improve germplasm collections and associated information for priority woody landscape plant taxa. Priority taxa for collecting include Carpinus, Celastrus, Cercis, Celtis, Cladrastis, Clethra, Cornus, Cotinus, Hamamelis, Hydrangea, Magnolia, Ostrya, Stewartia and Viburnum. With the American Public Gardens Association, coordinate, extend, and strengthen the North American Plant Collections Consortium’s continent-wide ornamental plant germplasm conservation program. 2) Strategically conserve and regenerate National Plant Germplasm System (NPGS) woody landscape plant germplasm efficiently and effectively and distribute samples and associated information worldwide. Regenerate, store, and/or maintain in situ plantings of priority germplasm and associated information, emphasizing Cornus florida, native Magnolia, and selected Viburnum species. Continue to increase to more than 40 percent the proportion of germplasm backed up at second sites, emphasizing critical back-ups. Develop monitoring methods and periodically assay the viability, health and vigor of stored germplasm. Distribute on request accessions and information that meet the specific needs of researchers, breeders, and growers. 3) Strategically characterize and evaluate priority NPGS woody landscape plant germplasm for key traits, such as taxonomic identity, genetic variability, invasiveness, and ornamental merit, thereby enhancing their utility to users, and the effectiveness of germplasm management. Incorporate that information into GRIN. In cooperation with other ARS and university collaborators, develop and apply new genetic markers for taxonomic identity, genetic diversity analyses, and population genetic structure for native Fraxinus species, Cornus florida, and Corylopsis. Ensure that Acer accessions in repository, especially those collected during North America-China Plant Exploration Consortium expeditions, are correctly identified taxonomically and adequately documented. Update and apply phenotypic descriptors for Acer, Halesia, Ilex, Viburnum and other priority taxa via in-house and cooperative evaluation. Incorporate phenotypic evaluation data into GRIN and/or other databases. Introduce especially noteworthy or valuable material to the public via a formal germplasm release.
1b. Approach (from AD-416):
Collect, propagate, and establish sexual and vegetative propagules of priority germplasm. Use in-house, contracted, and collaborative collectors, focusing on threatened, disjunct, or unique provenances. Train field reviewers, develop regional recruiters and mentor network for public garden participation in national collections program. Coordinate collections of priority genera with national collections holders to fill gaps in germplasm availability and diversity and minimize duplication. Preserve orthodox seed in medium (for distribution) or long term (cryogenic) storage facilities. Maintain recalcitrant species in short term or active collections, or distribute to backup or remote-site locations. Regenerate seed of living collections for distribution, medium and long term storage, using artificial pollinations and pollination cages. Monitor and assay viability of older seed accessions; use Cornus florida accessions to test viability using seed moisture content, seed viability equations as a proxy for other similar stored genera. Maintain current availability lists of germplasm for distribution; coordinate with national arboretum main collections; upload GRIN data on a regular basis for new accessions and matriculating germplasm from active collections. Screen Fraxinus species collected by USDA-ARS North Central Regional Plant Introduction station for ploidy levels; compare morphology and test new species hypotheses. Test cross amplification of Chionanthus-derived SSR markers for utility in Fraxinus germplasm. Use SSR markers from Cornus florida to test diversity levels from edges of species range with previously identified genetic clusters; adjust collecting areas as needed to maximize diversity. Screen Corylopsis germplasm for ploidy level and use AFLP to determine level of hybridization and species identifications. Collect voucher specimens of all Asian Acer taxa for verifying identification; cross-reference with other collections to determine collection gaps and rare taxa. Update GRIN data for priority genera; include descriptors for invasiveness using appropriate models. Propagate and distribute elite material to nursery collaborators for evaluation and introduction.
3. Progress Report:
The Woody Landscape Plant Germplasm Repository of the U.S. National Arboretum continues to target germplasm of native North American species important to the nursery industry. In support of these efforts, 74 accessions were collected during two plant expeditions into the southeastern United States targeting the states of Mississippi, Arkansas, Tennessee, Kentucky, and Virginia. Our primary objective was to target Fraxinus to support the efforts in the conservation of this genus in recognition of the potential loss of genetic diversity caused by the Emerald Ash Borer. We also visited the herbarium at the University of Mississippi to look for populations of other species of interest such as Magnolia pyramidata and to help lay the ground work for future expeditions. We continue to target northern populations of Cornus florida and have identified and attempted to collect from two sites approximately 40 miles south of Albany, New York and one accession through active collaborations to sample populations in Michigan. Along with these collections we have collected and added to our inventory: 3 Magnolia accessions, 7 Stewartia accessions, and 5 Hydrangea accessions. The repository has begun establishing seed orchards targeting 11 accessions including Syringa, Maackia, Viburnum and Aesculus. This process includes collaborations with the University of Maryland and the Beltsville Agricultural Research Center for planting out taxa whose seed do not survive long term storage. Germplasm distribution requests have continued to increase, with 231 requests for seeds; 178 accessions were distributed along with 21 samples for DNA extraction. This represents 67 genera and 141 taxa. We renewed our collaboration with the American Public Gardens Association in its efforts through the North American Plant Collections Consortium (NAPCC) in genetic resource conservation. This program continues to be critical to USDA in accomplishing its goal of plant genetic resource conservation of woody landscape plants. This collaboration includes improving curatorial standards and collections and is best represented by the planned conference in October of 2012 co-organized by APGA and the National Arboretum to discuss and educate the public garden community on international plant collection issues including the Convention on Biological Diversity and the new APHIS regulation NAPPRA. Additional germplasm was acquired for elucidating relationships between ploidy level and taxonomic rank within the cultivated Corylopsis. Additional herbarium vouchers have been made and sorted for determining species identifications in Asian maples. Flower production on potted Halesia was evaluated. In general, Halesia produce flowers well below the shoot apex, as much as one to two feet, and may vary with year. Preliminary data indicates optimal nutrition may have a positive effect; however, no effects were observed for variations in temperature.
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