seed banking

Heather Schneider, Santa Barbara Botanic Garden

Conservation seed collections support species’ survival by acting as an insurance policy in the face of extinction. They can also provide resources for research, restoration and reintroduction. A high-quality conservation seed collection has both depth and breadth – capturing genetic diversity within and geographic diversity among populations. Collecting and storing seeds by maternal line (i.e., seeds from a single individual plant represent one maternal line) provides depth to conservation collections. Previous research has suggested that collecting from 50 maternal lines throughout the geographic extent of a given population increases the odds of capturing the majority of the genetic diversity within that population. Capturing the maximum amount of genetic diversity possible from each population increases the integrity of a conservation collection. Further, keeping maternal lines separate ensures that each line can be equally represented in restoration and reintroduction efforts. Separating seeds by maternal line also creates opportunities for future research, especially when questions center on genetic differences within and between populations. When bulk collections are made, there is only a small chance that each maternal line will be represented when a subsample of the collection is removed for use and valuable information is lost. Although collecting by maternal lines makes seed collection and cleaning more complicated, the amount of information that is retained increases the value of the collection and makes the effort worthwhile.

Contributing Author(s): 
Date Recorded: 
Thursday, May 2, 2019

What kind of germination/growth chamber do folks recommend for seed viability testing?

Our growth chamber broke recently and we're hoping to replace it with something cost-affordable, reliable and not too big for our relatively small space. It will sit in a room shared with seed processing equipment (and people), a biomass oven and is used with some frequency.

Seana Walsh and Dustin Wolkis, National Tropical Botanical Garden

New fungal pathogens are threatening the most ecologically and culturally important native tree in Hawai‘i, ‘ōhi‘a (Metrosideros spp.). Two undescribed taxa of Ceratocystis cause Rapid ‘Ōhi‘a Death (ROD), destroying large stands of ‘ōhi‘a forest on Hawai‘i Island. In preparation for the potential future spread of ROD across the state, seeds of all Metrosideros taxa on all the Hawaiian islands need to be collected, banked, and reciprocated, for resistance testing and for use in potential, future reintroductions. One of the main challenges in initiating a coordinated effort to collect seeds on Kaua‘i is deciding how much seed to collect and from which locations. Seed zones, geographically delineated areas within which seed from originating zone can be transferred to help ensure material is ecologically appropriate for the local environment, were not established in Hawai‘i. Staff from the National Tropical Botanical Garden (NTBG) and Hawai‘i Department of Land and Natural Resources, Division of Forestry and Wildlife, worked together to create generalized provisional seed zones for the island of Kaua‘i. Further, a proposal submitted to the Hawai‘i Tourism Authority by NTBG, to collect, bank and reciprocate seed collections, was supported. Across all 10 seed zones and all four Metrosideros taxa native to Kaua‘i, our collection goal for 2018 is between 6 and 20 million seeds, through both single and bulk seed collections, from over 1,000 individual trees. This work is currently underway.

Contributing Author(s): 
Date Recorded: 
Thursday, May 3, 2018

Johnny Randall and Michael Kunz (North Carolina Botanical Garden, University of North Carolina at Chapel Hill), and Jamie Winshell, Corbin D. Jones and Gregory P. Copenhaver (Department of Biology and Integrative Program for Biological & Genome Sciences,University of North Carolina at Chapel Hill)

Venus’ flytrap (Dionaea muscipula) is the most widely recognized carnivorous plant, and endemic to only 100 km landward radius around Wilmington, North Carolina, USA. Although a few large populations occur on protected lands, the number of individuals is declining, entire populations are being extirpated, and a seemingly secure species is now vulnerable to local extinction and loss of wild genetic variation. We used Restriction site-Associated DNA sequencing (RAD-seq) to evaluate the genetic architecture of Venus flytrap populations across its entire range. In addition, we collected and banked over 25,000 seeds from 20 populations as a long-term conservation resource. Initial analysis of 160 RAD-seq derived markers indicate limited genetic variation within the first population sampled. Genetic variation was surprisingly heterogeneous across loci with some populations harboring appreciable variation and others harboring next to none. This initial analysis is ongoing for approximately 150 populations to provide a high-resolution assessment of the existing genetic variation, which will help guide future conservation efforts and understand species phylogeography.

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Date Recorded: 
Thursday, May 3, 2018

Dennis Whigham and Julianne McGuinness, North American Orchid Conservation Center

The North American Orchid Conservation Center (NAOCC) was developed by the Smithsonian and the U.S. Botanic Garden to conserve the diversity of native orchids in the U.S. and Canada. NAOCC ecologically-based conservation model has three guiding principles: Preservation through seed and fungal banks, Propagation, Education. NAOCC has a growing network of public and private collaborators working to collect and store seeds of native orchids to further the understanding their ecology, preserve genetic diversity, and provide material for use in research that supports propagation and restoration efforts. NAOCC's collaborative model for orchid conservation is guiding a new project to develop best practices and storage protocols for orchid seeds and their fungal associates. To address the urgent need for evidence-based standardized procedures, NAOCC and a number of its collaborators will study storage practices, conduct germination tests, and develop protocols for each species. Chicago Botanic Garden (CBG) took the lead on a grant application to the IMLS for funding for this project. NAOCC joins CBG, the New England Wild Flower Society, Minnesota Landscape Arboretum, Atlanta Botanical Garden, Fairchild Tropical Botanic Garden, Illinois College, the Mid-Atlantic Regional Seed Bank, and the Naples Botanical Garden to conduct the first systematic analysis of its kind regarding seed storage practices for North American native orchid species.

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Date Recorded: 
Friday, May 4, 2018

Heather Schneider, Santa Barbara Botanic Garden

In the fall of 2017, Dr. Heather Schneider from the Santa Barbara Botanic Garden attended the Kew Millennium Seed Bank Partnership’s three-week Seed Conservation Techniques Training Course. The course brought together conservationists from all over the world to improve conservation seed banking practices used by MSB partners. The course covered a variety of topics from seed biology to field work to processing and storage. At the end of the course, students were encouraged to create an action plan for improving their own seed bank techniques at home. Dr. Schneider will discuss some lessons learned and changes implemented at the Santa Barbara Botanic Garden resulting from this course.

Contributing Author(s): 
Date Recorded: 
Friday, May 4, 2018

Ed Guerrant, Rae Selling Berry Seed Bank

Penstemon peckii (G3-S3 Federal SOC) is an Oregon endemic with a relatively compact range in the semi-arid Ponderosa pine forest east of the Cascade Mountains. The vast majority of known populations (ca 93%) are almost entirely within the Sisters Ranger District of the Deschutes National Forest. A 1992 Species Conservation Strategy by Cindi O’Neil found that it is “Best adapted to open full sun habitats, low vegetative competition and natural fire.” The natural fire frequency was 7 to 15 years, but active fire suppression for many decades had diminished and degraded habitat. Number one in the “What we do not know” list is “How long does Peck’s penstemon seed remain viable in the soil seed bank?” To address that question, in 1992 we gathered seeds from multiple populations across the species’ range. We mixed seeds from 11 populations into a single, large bulk sample in order to compare their survivorship in the soil seed bank and in an ex situ seed bank. In addition to initial trials of fresh and dried and frozen seeds, samples have been removed from the field and ex situ seed bank after 6, 12, 18 months, and then at 4, 15 and now 25 years. The current round of germination trials of 25-year old seeds is still underway, but to date, approximately 26% of those stored in the soil and 51% in the freezer have germinated. The species clearly has the capacity to form a long-lived soil seed bank.

Contributing Author(s): 
Date Recorded: 
Friday, May 4, 2018

Chris Walters, Research Leader of the Plant Germplasm Preservation Research team at USDA-ARS National Laboratory for Genetic Resources Preservation

Knowing how long storedgermplasmsurvives is critical for effective banking of genetic resources. Longevity is inherently difficult to predict because there are so many factors controlling how cells respond to storage conditions. Uncertainty increases forgermplasmcollections of natural populations, especially rare species that might have additional issues with the reproductive biology or with assessments ofviabilityor aging. Storage conditions invariably involve manipulation of temperature and moisture, and this presentation will describe some of the basics of why this leads to long-term preservation of somegermplasmand what we think is going wrong when the desired longevity is not achieved. Preserving germplasm involves slowing down the rate that ‘clocks tick,’ and this means that we need to slow down the rate that molecules move. The most effective way to do this is by having molecules impede their own movement by pushing them together tightly and forming a solid (like a traffic jam). This process begins during development when cells accumulate dry matter to replace water, allowing molecules to come into close proximity naturally without deforming stresses. Cells from orthodox seeds shrink a little and solidify during maturation drying, but major mechanical stresses are easily avoided. Once in the solid, the rules for molecular movement are mostly dominated by how tightly the molecules are packed (determined by properties of the molecules and concentration of water) and by how much energy they have (determined by temperature). Given a particular molecular configuration in solidified cytoplasm, the effect of lowering temperature on mobility is predictable, as is the kinetics of reactions, such as aging, that are regulated by mobility. Lowering temperature slows down aging reactions in the same way in diverse seeds and spores; thus, reducing storage temperature from 25 to -18oC will usually increase longevity about 30 fold (if moisture is optimized). The good news is thatgermplasmthat survives 4 years at 25oC will survive about 120 years in the freezer. The bad news is thatgermplasmthat survives only 40 days at 25oC won’t survive much longer than 3 years in the freezer. Freezer temperatures appear to be a nexus for how molecules move in biological systems. Below -18oC, aging reactions appear to be driven by molecules vibrating, which has a low temperature dependency. Thus, a large temperature decrease gives only moderate benefits. Currently, we estimate a 3 to 5 fold increase in longevity by storinggermplasmcryogenically rather than in the freezer. Further complexity in structure and mobility of solidifiedgermplasmis introduced by the presence of oil droplets in the cytoplasm. We have linked lipid crystallization with faster aging in the freezer and explain this as the condensed structure of solidified lipids causing greater pore space, hence increased mobility, in aqueous domains of the cytoplasm. Collectively our work provides a theoretical framework to explain why lowering temperature and moisture affect longevity and to predict how longgermplasmstored at -18C will survive.

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Date Recorded: 
Thursday, May 3, 2018