Location: Floral and Nursery Plants Research
2021 Annual Report
Objectives
Objective 1: Efficiently and effectively acquire priority temperate-adapted woody landscape plant genetic resources; maintain their safety, genetic integrity, health and viability; and distribute them and associated information worldwide. [NP301, C2, PS2A; C1, PS1B]
Sub-objective 1.a. Acquire samples and associated information of select taxa via exploration, contract collecting, and exchange. Targeted taxa include: Cladrastis kentukea, Viburnum species, Quercus species, Acer saccharum subsp. leucoderme and floridanum, Lindera benzoin, and Hamamelis ovalis.
Sub-objective 1.b. Maintain and backup plant germplasm, including conduct germination tests on stored seed to determine viability of older germplasm; update seed collection and GRIN-Global database to reflect inventory; prioritize and regenerate or re-collect vulnerable accessions.
Sub-objective 1.c. Distribute accessions and information that meet the specific needs of researchers, breeders, conservationists, nursery professionals, and other stakeholders.
Objective 2: Develop more effective genetic resource maintenance, evaluation, and characterization methods and apply them to priority temperate-adapted woody landscape plant genetic resources. Record and disseminate evaluation and characterization data via GRIN-Global and other data sources. [NP301, C2, PS2A]
Sub-objective 2.a. Develop and apply molecular markers for analysis of genetic diversity, taxonomic identity, and/or population structure for Tsuga chinensis and other priority taxa.
Sub-objective 2.b. In collaboration with nurseries, botanic gardens, and university cooperators, evaluate horticultural merit of accessions collected under sub-objective 1.a and those already included in our living collections; disseminate information and superior germplasm or selections.
Objective 3: With other NPGS genebanks, Crop Germplasm Committees, and customers/stakeholders, develop, update, document, and implement best management practices and a Crop Vulnerability Statement for temperate-adapted woody landscape plant genetic resource and information management. [NP301, C2, PS2A]
Approach
High-quality germplasm identified from in situ populations or ex situ collections will be acquired in the most efficient manner. For many acquisitions, this will be through germplasm requests, exchanges, and local collecting. Domestic collections for the eight taxa identified as priorities (Cladrastis kentukea, Viburnum, Quercus, Hamamilis ovalis, Lindera benzoin, Fagus grandifolia, Sassafras albidum, and Acer saccharum subsp. leucoderme and floridanum) will focus primarily on eastern North America. Our approach will be to collaborate with local experts including other scientists, botanists, and collectors. The number of species targeted and collection goals in each specific effort will depend in part on the extent of the collaborators’ involvement and ease of access to sites.
We will use a contracted service for seed viability testing. Seed that is more than ten years old will be prioritized for viability testing based on the quality of passport data, its conservation status, and the number of requests received for that taxon. Seed that has no viability will be deaccessioned or inactivated following the NPGS Inactivation Guidelines developed by the PGOC. Seed will also be regenerated in-house or recollected. Seed from regenerated or collected accessions will be sent to the NCGRP in Ft. Collins for long-term backup.
We will follow our established protocols for meeting distribution requests that come through GRIN-Global for accessions already in the system. We will also distribute seeds of newly acquired taxa to collaborators for conservation or evaluation. Basic passport data (taxonomic information, collection locations, dates) are maintained in GRIN-Global for each accession. We will supplement these data with evaluation and descriptive information and images from collaborative evaluation projects which will add value to the germplasm.
To evaluate germplasm, we will use SSR markers to determine relationships among and diversity within accessions of Tsuga chinensis and Lindera benzoin. We will also evaluate the horticultural merit of germplasm accessions through collaborative agreements with several cooperators. Plants will be evaluated for various horticultural and production traits. Data will be collected after three years of field trials, and for two to five years subsequently, depending on the genus.
In order to update and implement best management practices and a Crop Vulnerability Statement for germplasm, we will maintain and establish collaborations with WLPGR users and other stakeholders to ensure that the collections are relevant, well-curated, accessible, and effectively utilized. We will work with the Crop Germplasm Committee to develop a list of targeted genera or species which are most vulnerable or otherwise in need of conservation. We will also update our internal “Operations Manual”, which provides specific guidance on identification, collection, maintenance, distribution, and evaluation of germplasm specific to the WLPGR, and also addresses database management, invasiveness, staffing, equipment and facilities, the WLPCGC, and safeguarding germplasm.
Progress Report
Substantial progress was made within all project objectives during FY2021. Within Objective 1, we added over 600 new accessions to the Germplasm Repository, representing 250 species. Wild-collected material was sourced from 37 U.S. states and six countries. 80% of new accessions were received as seed to be maintained in the seed bank and the remaining 20% of accessions represent plants that will be used in evaluation, regeneration, and permanent display at the U.S. National Arboretum. A new approach was developed and implemented for lineage-based tracking of germplasm and associated data within Germplasm Resources Information Network (GRIN) Global. This method consolidates genetic resource inventory that was previously duplicated in time and space and employs an intuitive coding language that allows more efficient germplasm management and distribution to stakeholders.
Among target taxa that are prioritized for collection, Lindera benzoin, Quercus spp., and Viburnum spp. acquisitions were most significant. Lindera seeds and plants were acquired from Delaware (two populations), Maryland (two populations), Massachusetts, North Carolina, Ohio, and Virginia. Colleagues in the Floral and Nursery Plants Research Unit (FNPRU) began investigations on a Lindera-specific virus, and we provided leaf tissue from additional L. benzoin populations in Maryland and symptomatic Lindera spp. in cultivation to aid research efforts. 17 Quercus accessions were added to GRIN Global, representing seven species. Most notably, acorns from six wild populations of Quercus boyntonii were received from Alabama, where it is an endemic, critically endangered species. Seeds of this species cannot be held in storage but were successfully germinated, and the resulting plants will be maintained as long-term conservation collections. 21 Viburnum accessions (seven species) were acquired via contract collectors and germplasm exchange from 12 U.S. States, China, and Japan. These accessions have been incorporated into the seed bank or planted in controlled regeneration plots.
We created nine additional 4.5m x 4.5m controlled plots to expand seed regeneration capabilities. A total of 43 accessions were planted in regeneration tents, and bees were introduced for controlled pollinations. An orchard planting of Magnolia ashei was created to consolidate holdings of this Florida endemic, endangered tree. Seeds of this species cannot be held in cold storage, so this orchard planting will be utilized as a propagule source of shoot-tips which can be harvested periodically for cryopreservation. Seed viability testing was performed for 50 accessions with significant quantities (>1500) of seed, and accessions with suitable viability were sent to National Seed Storage Laboratory (NSSL) for backup.
Germplasm distributions included 469 accession items representing 258 unique taxa. Germplasm was primarily sent to U.S.-based institutions, but also distributed to eight other countries. Distributions were made in the form of cuttings (48%), seeds (34%), live plants (17%), leaf tissue (<1%), and pollen (<1%). Among the following categories of stakeholders, the proportion of total cooperators/total items are as follows: Academia (20%/8%), Individual Researchers (24%/9%), US National Arboretum Staff (4%/2%), NGOs (10%/14%), Nurseries (8%/4%), Public Gardens (24%/45%), and USDA-ARS (10%/17%).
Within Objective 2, we developed templates for migrating genetic data into GRIN Global and used these to add SSR primer data and corresponding citations for 50 primers developed for use with Magnolia. In continuation of genetic analysis of Sassafras albidum from across the species’ range, we contacted more individuals to submit leaf tissue from unsampled regions in Ohio and the southeastern states. Some Sassafras samples submitted in 2019 were of poor quality and DNA extraction was not possible; we therefore sent collection kits to collectors to resample these populations.
We initiated a long-term trial to evaluate the merit of Tsuga chinensis (Chinese Hemlock) as a landscape plant in the extreme Southeast U.S. Populations wild-collected from three Chinese provinces will be replicated at sites in Florida, Mississippi, and Texas, with a control planting in Beltsville, Maryland. We have not been able to identify any dwarf forms of Lindera benzoin among wild populations in the U.S., and instead initiated a seed mutagenesis experiment to induce compact form via Ethyl methanesulfonate (EMS). Seedlings from treated seeds have displayed slower growth rates and are currently being evaluated in comparison to non-treated seedlings. This evaluation will continue in Beltsville, Maryland, until selections can be made and distributed for evaluation by outside cooperators.
Select trees of Chimonanthus, Magnolia, Prunus, and Tilia were propagated from cuttings for further evaluation. These individuals displayed novel, desirable landscape characteristics including fastigiate and compact growth and therefore merit distribution and replicated evaluation.
Under Objective 3, stakeholder collaborations were maintained and established with key stakeholders. In our collaborative partnership with the American Public Gardens Association’s Plant Collections Network (PCN), we planned and gave presentations for a virtual training workshop for over 30 new reviewers of PCN applicants. This effort substantially grew the pool of reviewers across the U.S. and Canada and introduced many of the trainees to the merits of PCN accreditation. The National Arboretum submitted a PCN application for Magnolia and is scheduled for an onsite review of Magnolia and Quercus (submitted FY20) in summer 2021. We expect both Quercus and Magnolia collections to receive full accreditation status.
The National Arboretum’s Oak and Magnolia collections were accepted as part of the Global Conservation Consortia (GCC) of the Botanic Gardens Conservation International (BGCI). For the Magnolia GCC, we were asked to be a member of the steering committee and a ‘species champion’ for Magnolia ashei. The steering committee will aid the broad-scale efforts of Magnolia conservation in the U.S., while the ‘species champion’ is intended to lead the fine-scale conservation of this taxa among ex situ collections. To that end, we wrote a case study of the U.S. National Arboretum’s conservation efforts with Magnolia ashei for inclusion in the Global Conservation Gap Analysis for Magnolia.
We submitted, and were approved for, a joint Arboretum accreditation program managed by Arbnet and BGCI. We received the highest level of accreditation available based on the level of tree research and conservation activities. The Arbnet/BGCI network of accredited collections offers opportunities for collaborative research opportunities in the future.
We continue to work with the Woody Landscape Plant Crop Germplasm Committee and contributed to writing and editing an updated crop vulnerability statement. In addition, we joined a newly created subcommittee within the Plant Germplasm Operations Committee for seed research to improve seed standards across NPGS.
Accomplishments
