Location: Floral and Nursery Plants Research
2023 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
This is the final report for the Project 8020-21000-157-000D which ended March 5, 2023. New NP301 OSQR approved project 8020-21000-158-000D, entitled “Manage, Expand, and Evaluate the U.S. Collection of Temperate-adapted Woody Landscape Plant Germplasm and Associated Descriptive Data” has been established and began on March 6, 2023.
In this project, under Objective 1, we maintained a continuous effort to acquire new germplasm and make it available to stakeholders. Over this project’s lifecycle, a total of 1858 of new accessions were added to the curated, repository collections. New accessions were primarily comprised of US native woody plants with ornamental, landscape, and conservation value, as well as select taxa from temperate Asia and ornamental cultivars obtained directly from breeders. We focused our wild-collection efforts in the eastern US and worked with contract collectors and collaborators to make additional collections from the western US. The taxonomic diversity of plants assigned to our site necessitates a wide array of management practices to maintain and conserve germplasm. During this project’s lifecycle we reviewed and updated our accession-inventory maintenance policies in GRIN-Global to designate appropriate management and distribution activities for each accession, as a function of storage behavior and maintenance requirements of each taxon. A total of 2104 accession-items were distributed to 439 requestors during this project. Annually, between 15-30% of distributions are sent to botanic gardens and arboreta in the United States to be incorporated in other ex-situ living collections, thereby serving as informal germplasm backup for our site. Researchers in academia, industry, and commercial horticulture professionals comprise the majority of additional germplasm requests each year.
Under Objective 2, we conducted genetic diversity studies on Magnolia ashei, Sassafras albidum, and Tsuga chinensis. In addition, we obtained leaf samples from all documented populations of Hamamelis ovalis for an upcoming study on genetic diversity and population structure. We made clonal selections for two germplasm releases - Styrax japonicus ‘Burgundy Moon’, selected for burgundy-red pedicels, and Viburnum nudum ‘Little Cherub’, a strongly compact form of a U.S. native species.
Under Objective 3, our 28-year collaboration with the American Public Gardens Association remains strong and productive, with 158 existing Nationally Accredited Collections in the Plant Collections Network (PCN). The National Arboretum hosted the American Public Garden’s Association PCN meeting in 2019, and during the COVID19 pandemic we provided virtual sessions to PCN members including training for collection reviewers and methods for writing a collection develop plan. We remain active participants in the North America-China Plant Collecting Consortium (NACPEC) and the Plant Collection Collaboration (PCC). Both NACPEC and PCC are comprised of botanical gardens that coordinate plant collecting and ex situ conservation projects, and freely exchange germplasm. With the Woody Landscape Plant Crop Germplasm Committee, we wrote a crop vulnerability statement for woody plants.
Accomplishments
1. ‘Little Cherub’ – a unique native Viburnum cultivar. The introduction of new landscape plants is one of the driving forces behind the ornamental horticulture industry. New woody ornamental plants increase genetic diversity in the landscape, offering resiliency to unpredictable weather patterns and new plant pests. Researchers from the US National Arboretum in Beltsville, Maryland, released a new compact cultivar of Viburnum nudum called ‘Little Cherub’. This new cultivar reaches a height of approximately three feet at maturity, whereas the typical species can exceed 15 feet and is too large for many residential landscapes. ‘Little Cherub’ is well suited as a specimen plant or in mass plantings and, because of its compact size, works well near walkways, in mixed perennial borders, or in container gardening. This selection represents a U.S. native shrub and helps to meet the needs of a burgeoning native plant market, while also providing important ecosystem services for native pollinators and wildlife.
