Location: Office of The Director
2024 Annual Report
Objectives
Objective 1: Conduct research to develop genetic resource regeneration, maintenance, evaluation, or characterization methods and, in alignment with the overall NPGS Plan, apply them to priority arid-adapted plant genetic resources to avoid backlogs in genetic resource and information management.
Sub-objective 1.A: Based on the data collected in the NPGS Plan, develop a long term PGR management strategy for addressing current needs and avoiding future backlogs in the management of the NALPGRU arid lands emerging crop collection.
Sub-objective 1.B: Investigate and develop new PGR management methods for NALPGRU crops. Collect evaluation and characterization data and make them available through GRIN-Global and other data sources.
Objective 2: Conduct research to develop regeneration methods and, in alignment with the overall NPGS Plan, apply them to priority plant genetic resources that require long seasons and/or arid climates so as to avoid backlogs in genetic resource regeneration.
Objective 3: Acquire, distribute, and maintain the safety, genetic integrity, health, and viability of priority arid-adapted plant genetic resources and associated descriptive information.
Sub-objective 3.A: Strategically increase genetic diversity of the Parthenium (guayule) and Opuntia collections by addressing stakeholder-identified gaps through plant exploration and exchange.
Sub-objective 3.B: Continue to maintain the highest possible availability, quality, and security of seed and clonal germplasm in diverse collections of arid-adapted new crops.
Sub-objective 3.C: Distribute high-quality germplasm in the form of seeds, cuttings, and plant tissue to stakeholders worldwide.
Approach
1.A: We will consult with partners to create a PGR management strategy based on the NPGS Plan. This strategy will include prioritized lists of backlogs to address by crop as well as plans for further reducing and preventing backlogs in the future.
1.B: We will identify core diversity and production subsets in the guayule collection. We will investigate seed quality in guayule regeneration by comparing caged and open-pollinated plants. If caging does not impact quality, we will follow with a comparison of caged plots with and without pollinators. We will phenotype the Opuntia collection, prioritizing the traits most useful to requestors (fruit soluble solids content, fruit size, seediness, spine length, etc). Additionally, we will upload existing photos to GRIN-Global.
2: Regeneration and back-up of accessions from other NPGS sites will be coordinated with the NPGS curators responsible for the crops. This service regeneration objective is distinct from regenerations for crops maintained by NALPGRU (3.B). Regeneration involves growing plants in the field, tracking inventory, controlling/facilitating pollination, monitoring for pests and diseases, collecting descriptor information and photos, harvesting and cleaning seed, and returning increased seed to the priority site along with data for upload to GRIN-Global.
3.A: We will coordinate with the New Crops CGC to plan exploration trips and apply for funding through the Plant Exchange Office (PEO). We will add diversity in Parthenium species through the Seeds of Success program and pursue options of in situ conservation on public lands in Texas through the PEO. We will conduct a gap analysis of the Opuntia collection using recently completed phenotypic and genotypic diversity analyses to determine future collection priorities.
3.B: NALPGRU collections are maintained as clonal and/or seed accessions, depending on the needs of the crop. Seed must be periodically regenerated to maintain viability and distribution. Each year seed inventories will be analyzed to identify accessions with the highest regeneration priority following the PGR management strategy developed in Sub-objective 1.A. Also following the PGR management strategy, seed of the best available quality will be transferred for backup to NLGRP in Ft. Collins, CO. The guayule field plots will be replanted from original seed in 4 stages. The Opuntia field block also requires re-propagation, and will be installed over 2 years. Some existing Opuntia has symptoms of ‘cladode-swelling disease’. The disease can be eradicated by regenerating the plant from asymptomatic tissue or cleaned up using cycles of thermotherapy. This program began in the last planning cycle, and we will continue to produce asymptomatic material for planting in the new perennial block.
3.C: NALPGRU receives requests for germplasm through GRIN-Global and reviews for legitimacy. Domestic requests are shipped directly after meeting phytosanitary requirements. International requests are sent to NGRL in Beltsville for coordination with APHIS and shipment to the destination.
Progress Report
This project supports the mission of the National Plant Germplasm System (NPGS) by maintaining, evaluating, and distributing accessions of arid-land industrial crops and providing a long season regeneration site for accessions with special climatic requirements from other NPGS sites.
In June 2023, a postdoctoral research associate was hired to serve in the curator/agronomist position on an interim basis and initiated several research and management projects to improve the regeneration, safety, and availability of arid-lands crops, test new pollinator treatments in service regenerations offered to other NPGS sites, and initiate germplasm acquisition efforts in high-priority arid-land crops. Additionally, this interim curator/scientist has facilitated greater stakeholder engagement and has been supporting the technical staff in outreach and communication efforts. The long-term technical support staff continue to provide high-quality field, greenhouse, and seedbank support, ensuring the integrity of the collections and regeneration services provided with the resources available.
Progress on Objective 1 includes research activities to improve genebank operations, enhance characterization of the collections, and development of a long-term plant genetic resource management strategy for the arid land crops collection in Parlier, California. The recent hiring of an interim curator/scientist has provided the resources to initiate multiple projects and experiments to address these goals.
To improve guayule seed regeneration protocols, a two-year experiment was initiated testing the effect of supplemental fly pollinators on improving the proportion of viable seed produced. Most guayule accessions are facultative apomicts that do not explicitly require pollination to produce seed. However, guayule seed regenerations often produce a high proportion of non-viable seeds, many of them unfilled achenes that reduce seed availability and the efficient management of the collection. Historical literature indicates that providing supplemental insect pollination may improve the production of viable seed, even in primarily apomictic accessions. This hypothesis is currently being tested in a replicated field trial with multiple pollination management treatments. In spring 2024, plots were selected, caged, and have been subjected to the designed pollinator treatments. The first seed has been harvested, and this process will be completed with seed cleaning in the next three months. Seed harvested from this trial will not only be phenotyped with traditional measures of seed filling and viability, but new non-destructive and high-throughput methods will also be pursued.
In addition to these efforts, 2024 was the final year of a collaboration with researchers at University of Nevada, Reno, characterizing four NPGS Opuntia accessions for biomass production across multiple fertility and irrigation treatments across three years and three locations. The final field trial was harvested, and material is currently being processed.
Progress toward Objective 2 was achieved in two main areas: 1.) regenerations for other sites and 2.) serving as the backup site for the national hazelnut collection. ARS researchers in Davis, California, served other NPGS sites by regenerating annual accessions that cannot produce seed at their home sites because they do not have a long enough growing season or suffer excessive pest or disease pressure due to climate. The process is executed from receipt of seed at the beginning of the growing season, through planting in the greenhouse, transplanting to the field (unless the seed is sown in the field directly), isolating from pollinators (if necessary), harvest, and shipment of increased seed back to the home site. This includes frequent coordination with the curators of these crops and photo updates, some of which they use to add to the available descriptors on the Germplasm Resources Information Network (GRIN-Global). In FY 24, regenerations planted for other NPGS sites included 267 garlic, 37 sunflower, 10 brassica, three winter squash and one dalea accession. The hazelnut backup collection from Corvallis, Oregon, is being reestablished with newly propagated plants. In FY 24, five new trees were delivered from the home site to be planted in Parlier, Carlifornia. This backup planting is ongoing and serves as security from the growing threat of filbert blight disease in Oregon.
In addition to these services, a two-year research trial collaboration with the NPGS researchers in Geneva, New York, comparing the pollination efficacy of honeybees and flies in Cucurbits was initiated this year. This replicated field regeneration trial is being performed in both Parlier, California, and in Geneva, New York. Results of this trial will allow comparisons of pollinator efficacy, seed quality, and costs for both of these treatments at each location to better inform future Cucurbit regeneration efforts. In spring 2024, replicated field plots were planted, caged, and subjected to multiple “treatments” of different pollinator strategies. Seed will be harvested, cleaned and analyzed in the next three months.
Objective 3 focuses on the maintenance, acquisition, and distribution of the collection of arid-land industrial crops. The priority crops are a combination of clonal accessions (prickly pear, jojoba, yucca and agave) and seed propagated accessions (meadowfoam, bladderpod, guayule, buffalo gourd). In FY24, ARS researchers and suppport staff in Parlier, California have shipped 35 order requests for germplasm from California to domestic and international researchers and have several more waiting for phytosanitary clearance.
A substantial effort was initiated this year to begin the process of re-establishing the Opuntia field collection to safeguard the integrity of this collection and improve the availability of many Opuntia accessions that are currently unavailable because of their poor condition in the current field collection. Planting beds and irrigation were established in new field in 2024 that is less prone to flooding. Continuing into FY24, cladodes from the current field collection were sampled to be treated with a multi-generational heat treatment protocol to address an endemic cladode stunting disease and provide symptom-free propagative materials for the new field collection. This process typically requires two to three treatment generations, and a limited number of cladodes will be ready in fall of 2024 for planting with additional materials becoming available in 2025. In addition to these field and propagule preparations, extensive efforts were made in 2024 sourcing and reviewing historical provenance records for each of the Opuntia accessions to identify redundant materials. Based on these records, 26 duplications out of 288 accessions were identified and removed from the planting list.
In March 2024 the first seed increase of a historically important and unique collection of guayule was initiated with seed harvested in June through August. These newly acquired seed were developed by Japanese-Americans interred at the Manzanar War Relocation Center during World War II under the mandate of the Emergency Rubber Project. These materials were maintained by descendants of the former internees and donated to the NPGS in 2016. Plots were established in November of 2022 and the plants reached the appropriate size for seed production in 2024. Cleaned seed of these materials will be accessioned in GRIN and made publicly available for the first time before the end of October 2024. Guayule serves as an alternative source of natural rubber with significant commercial interest and is a high-priority collection. Currently, the NPGS collection has 47 available accessions, and the addition of these historically important guayule materials will be an important addition.
An additional new source of guayule germplasm was established in April 2024, when eight field plots of novel guayule germplasm collected in western Texas in 2018 by ARS scientists were established in Parlier, California. These were derived from a much larger seed collection, but these eight had viable seed that survived the establishment phase. It is expected that over the next two years these plots will reach a sufficient maturity to enable seed production to be added to the permanent NPGS guayule collection.
In November of 2023, ARS researchers from Parlier, California, along with external collaborators from the New Crops CGC visited multiple sites in southeastern Arizona to investigate the existence and availability of naturalized guayule populations for future seed collections. Out of four previously reported populations only one was found to still be accessible, and a new fifth population was discovered. The fifth population occurs on land owned by the University of Arizona and is available for a future collection pending permission from the University. This process has been initiated, and if permission is granted, seed will be collected in June 2025.
In collaboration with partners in the New Crops CGC, a core collection of seven NPGS guayule accessions has been proposed to represent the diversity of the collection. Sufficient seedlings for three field plot replications of each accession have been established in the greenhouse for a fall 2024 or spring 2025 field planting. Establishment of this replicated core collection will enable improved seed availability and plant materials to meet increased demand for these accessions after the publication of this core collection in peer-reviewed literature.
Accomplishments
Review Publications
Morris, J.B., Dierig, D., Heinitz, C.C., Hellier, B.C., Bradley, V., Marek, L. 2023. Vulnerability of U.S. new and industrial crop genetic resources. Industrial Crops and Products. 206. Article 117364. https://doi.org/10.1016/j.indcrop.2023.117364.
Neupane, D., Niechayev, N.A., Petrusa, L.M., Heinitz, C.C., Cushman, J.C. 2024. Biomass production of 14 accessions of cactus pear (Opuntia spp.) under semi-arid conditions. Journal of Agronomy and Crop Science. 210(2). Article e12705. https://doi.org/10.1111/jac.12705.