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ARS Home Northeast Area Washington, D.C. National Arboretum Floral and Nursery Plants Research Research





- Rounsaville, Todd
- 2023
- Publications
- Plant Genetic Resources, Genomics and Genetic Improvement (301)

Research Project: **Location:
                            Floral and Nursery Plants Research** Project Number: 8020-21000-158-000-D
                        
                        Project Type: In-House Appropriated Start Date: Mar 6, 2023
                        
                        End Date: Mar 5, 2028 **Objective:**
                        
                        Objective 1:  Conduct research to develop genetic resource maintenance, evaluation, or characterization methods and, in alignment with the overall NPGS Plan, then apply them to priority woody landscape plant genetic resource and information management.  
Sub-objective 1.A: 
	Develop and apply molecular markers for analysis of genetic diversity, taxonomic identity, and/or population structure for priority taxa.
Sub-objective 1.B: 
	Perform ecophysiological research on seed cryopreservation and dormancy breaking for priority taxa 
Sub-objective 1.C: 
	In collaboration with ARS and external stakeholders, evaluate the horticultural merit of accessions in the USNA living collections and those collected under sub-objective 2.A
Sub-objective 1.D: 
	Conduct research and conservation initiatives with the USNA living collections, as well as collections of other botanic garden collaborators, which highlight the value and utility of ex situ, data-driven collections.

Objective 2:  Acquire, distribute, and maintain the safety, genetic integrity, health, and viability of woody landscape plant genetic resources and associated descriptive information, including integrating select genetic resources and information from other collections at the U.S. National Arboretum. 
Sub-objective 2.A: 
	Acquire samples and associated information of select taxa via exploration, contract collecting, and exchange.  
Sub-objective 2.B: 
	Maintain and backup plant germplasm, including seed viability testing; seed regeneration via controlled pollinations; offsite accession backup; and asexual propagation of valuable clonal accessions.
Sub-objective 2.C: 
	Distribute germplasm and information that meet the specific needs of researchers, breeders, conservationists, nursery professionals, and other stakeholders.  
Sub-objective 2.D: 
	Maintain up-to-date NPGS accession records within GRIN-Global and expand the available resources within GRIN-Global to include relevant information from the USNA Herbarium, the USNA living collections, and genetic and phenotypic information generated by Objective 1 of this project and other FNPRU researchers. **Approach:**
                        
                        Analysis will be conducted to identify taxonomic, geographic, and genetic gaps within the collections maintained as part of the Woody Landscape Plant Germplasm Repository.  Combined with historical GRIN-Global request data and input from stakeholders, new acquisitions will be prioritized to meet contemporary demand from nursery, conservation, breeding, and other research cooperators.  High quality germplasm will be identified from in situ populations or ex situ collections and acquired in the most efficient manner. For many acquisitions this will be done through germplasm requests, contract collectors, and ARS expeditions. 

The storage and maintenance of existing and newly acquired germplasm will utilize multiple sites and methods based on the biology and conservation significance of each taxon.  Species with dessication-tolerant seeds (‘orthodox’) will be maintained at -20 degrees C, with a backup sample sent to NLGRP when sufficient quantities allow, and living plants propagated to fulfil research and conservation goals.  Species with dessication-intolerant seeds (‘recalcitrant’) will be maintained as living plants as part of the USNA living collections, distributed to stakeholders via GRIN-Global, and shared with external botanic garden collaborators as part of jointly managed ‘meta-collections’. Basic research will be conducted to develop in vitro or shoot-tip cryostorage methods to maintain recalcitrant taxa. Regeneration of seed and clonal inventories will be performed as needed based on regular monitoring of plant health as well as seed quantity and viability in storage.

To meet the needs of stakeholders, we will continue to improve the quantity and quality of taxa and associated data maintained in GRIN-Global. This includes the addition of genetic and phenotypic data, images and supporting attachments, and greater connectivity of data from the USNA living and herbarium collections. New initiatives will be developed to improve the utilization of WLPGR germplasm inventories and data, primarily through stakeholder engagement and the cultivation of new GRIN-Global cooperators.

Basic and applied research will be conducted to improve the management, availability, and long term conservation of woody plant germplasm.  Priority taxonomic groups (Fothergilla, Hamamelis, Ilex, Lindera, Magnolia, Stewartia, and Viburnum) will be acquired in support of diverse research objectives. Genetic markers will be used to assess the population genetic structure of priority North American taxa to guide conservation priorities at the population level and improve the genetic diversity of ex situ collections. We will study seed-aging in storage to optimize seed storage conditions for long-term preservation.  For taxa with complex or unknown mechanisms of seed dormancy, we will conduct studies to develop rapid, synchronized germination methodologies to enable broader usage of these taxa in the nursery and plant breeding industries. We will evaluate underutilized species and select clones for potential as new landscape plants, including recently described species that have not entered the nursery trade.


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