Location: Floral and Nursery Plants Research
2020 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 FY2020. In fulfilment of Objective 1, acquisition of germplasm and associated data consisted of 352 new accessions for the US National Arboretum. Of these, 252 (72%) originated from the WLPGR. The majority of incoming germplasm for the WLPGR was received with known, wild origin (84%) and arrived as seed (76%). In total, these accessions represent 200 unique taxa from 40 different plant families.
For targeted taxa, desiccation-intolerant seeds of Quercus pagoda and Quercus lyrata were collected by the WLPGR in October and stratified immediately for propagation. In January, the WLPGR collaborated with Bartlett Arboretum and Chicago Botanic Garden to collect ramets of Hamamelis ovalis; with a total of 15 populations sampled in Alabama and Florida. Through a partnership with the Mid-Atlantic Regional Seed Bank (MARSB), seed from 50 Viburnum populations (5 unique species) were obtained and deposited in the seed bank. Collection of Cladrastis kentukea leaf samples continued in June and July via a partnership with a local botanist in Kentucky. Leaf samples will contribute to a study of genetic diversity across the species’ range.
Among WLPGR seeds that underwent viability testing by the USDA Forest Service, a subsample of seed was sown in June for those with low (<75%) viability. Based on germination in the greenhouse, these accessions will be prioritized for controlled regeneration, seedling distribution, or recollection. Protocols were put in place to assess viability of all incoming seed accessions of sufficient sample size in the future, as well as a schedule for additional testing at multi-year intervals in order to assess viability loss over time.
Germplasm and data for 337 accessions were distributed to professional stakeholders. Requestors consisted of 64 institutions including 14 botanic gardens and arboreta, 6 universities, and 19 commercial nurseries. Additional germplasm recipients were breeders, municipalities, individuals, and other USDA-ARS germplasm repositories. 266 distributions (79%) were mailed as seeds, while the remainder of material was sent as cuttings, seedlings, or rooted plants, based on requests and WLPGR availability.
Within Objective 2, we solicited and received 219 leaf samples of Sassafras albidum to determine genetic relationships in response to the threat from a fungal pathogen that causes laurel wilt. Analysis using 27 existing SSR primer pairs revealed 2 pairs displaying polymorphisms. Moving forward we will screen for additional SSRs to better understand this species’ diversity and allow more focused efforts for germplasm preservation.
Under Objective 3, the WLPGR and USNA staff have been actively preparing applications for important collections to be accredited within the American Public Gardens Association’s Plant Collections Network (APGA PCN). The USNA Acer collection was recently accredited, an application has been submitted for Quercus, and additional applications are being completed for Lagerstroemia, Magnolia, and Prunus. The PCN application requires specific plans for each collection’s disaster preparedness and future development. The latter, Collection Development Plans, are strongly linked to the WLPGR program such that collection gaps at the species or population level can be identified and prioritized for collection and additional backup in the seed bank. The PCN Acer, Magnolia, and Quercus collections represent the three temperate ‘Multisite Collections’, which are held by approximately 8-20 different public gardens (per taxon) due to the taxonomic breadth and range of growing conditions required. As multisite members, the WLPGR will more effectively be able to elucidate germplasm gaps among members and facilitate future collections and distributions.
The WLPGR helped to organize and lead a PCN virtual forum in July. The focus of the forum was safeguarding plant collections through collaborative partnerships, and three presentations were given to highlight various strategies and avenues for collaborative work with different stakeholders.
Accomplishments
