Megan Philpott, Valerie PenceL*, Cincinnati Zoo & Botanical Garden, United States *Speaker
Threats to global plant biodiversity compel the need for ex situ collections of species worldwide. However, the subset of species known as exceptional plants are often overlooked. These species produce few or no seeds or produce recalcitrant seeds. The Center for Conservation and Research of Endangered Wildlife (CREW) at the Cincinnati Zoo & Botanical Garden maintains a liquid nitrogen bank of exceptional plant seeds and tissues known as the CryoBioBank®. CREW has partnered with the Lyon Arboretum in Honolulu to develop cryopreservation protocols for 21 endangered exceptional Hawaiian plant species and bank them in the CryoBioBank®. To date, micropropagation protocols to produce target tissues have been tested in 13 species, and cryopreservation protocols have been tested in 7 species. As an example, in Cyrtandra gracilis, micropropagation on medium containing 2mg/L of the auxin indole-3-acetic acid and 0.1mg/L of the cytokinin 6-benzylaminopurine induces shoot organogenesis on excised leaves. These leaves were dissected into leaf bud segments and compared with shoot tips for survival after liquid nitrogen storage. Cryopreservation of shoot tips using droplet vitrification (DV) with PVS2 yielded 0% survival, while leaf bud segments yielded 20% survival. DV using PVS3 increased survival in these leaf buds to 60%. Cryopreservation of leaf bud segments immediately after bud primordia formed yielded 25% survival compared to 50% survival if the buds were left to develop into shoots before cryopreservation. Shoot tips from another species, Melicope mucronulata, have been banked in the CryoBioBank® using the DV method following an experimental survival rate of 57% after 2 days of pre- culture on a 0.3M mannitol medium instead of one day on 0.3M mannitol and one day on 0.5M mannitol medium. This project will result in the long-term protection of many endangered exceptional Hawaiian species that would otherwise be unbankable using conventional methods. (Supported by IMLS grant #MG-30-17-0055-17).
Christina Walters, Jennifer Crane, Lisa Hill, United States Department of Agriculture., USDA-ARS
Seeds of papaya (Carica papaya) are tolerant to desiccation, but they are quickly damaged when stored at -5 to -20C. The seeds have a high lipid content that reflect “tropical oils,” which are high in saturated and mono-unsaturated fatty acids. Differential Scanning Calorimetry (DSC) experiments show that the lipids tend to crystallize into alpha and beta crystals and then re-crystallize to more stable crystalline beta prime structure as the seeds slowly pass through the -25 to +5C temperature range. A working hypothesis is that these transitions are associated with the poor storage response of papaya seeds. Cooling and warming sufficiently quickly (~ 50C/min) to liquid nitrogen temperatures allowed only the alpha-type crystals to form and slowed recrystallization. Seeds survived longer when stored at liquid nitrogen temperatures. However, after 15 years of storage, papaya seeds showed measurable degradation that may be associated with 1) multiple freeze-thaw cycles that occurred when retrieving samples for monitoring, 2) failure to warm seeds adequately before they were tested for viability, or 3) degradation processes that continue at liquid nitrogen temperatures. Papaya seeds serve as a convenient model to study a large class of seeds within the ‘intermediate’ storage category that originate from tropical or subtropical areas and cannot be stored using conventional seed banking methods. We show that storage at liquid nitrogen temperatures offers improved success, but may not provide long-term storage usually anticipated at such low temperatures.
Tuesday, July 23, 2019
Nellie Sugii, a key partner in the part of the collaboration focused on Hawaiian species, stands in her new micropropagation lab at Lyon Arboretum.
The Hawaiian flora represents ~45% of all plants listed by the U.S. Fish and Wildlife Service as threatened or endangered. The Lyon Arboretum's Seed Conservation Laboratory (Lyon S.C.L.) conserves many of these imperiled plants through conventional seed banking. However, the seeds of many rare Hawaiian plants have never been formally described or photographed. Receiving fruit and seed collections from collectors across the Hawaiian Islands presents staff with a unique opportunity to document characteristics of these seeds through photography. Initially, we used a digital SLR camera to photograph incoming fruit and seed collections, but encountered challenges in accurately capturing the details of very small seeds. With limited knowledge of microscope photography and a modest budget, we decided to investigate a setup that could be utilized for seed photography. After some research into different brands and models, we decided on an Olympus SZ61 stereo microscope, with an LW Scientific Inc. MiniVid camera, and ToupTek's ToupView version 3.7 software. Using this microscope-camera setup we have captured more than 500 images of Hawaiian seeds representing over 150 taxa, including many C.P.C. sponsored species. As new material comes into the Lyon S.C.L., we continue to add new species to our seed photo collection and are working towards making these photos available to students and researchers through an online platform.
Hawaii has approximately 1400 native plant species of which more than 90% are found nowhere else in the world. However, at least 30% of these species are endangered and 100 have already gone extinct due to land use change, ongoing pressure from introduced species, and the loss of pollinators and dispersers.To address these threats, Hawai'i has a well established conservation community with a history of partnerships between state, federal and private entities. The Honolulu Botanical Gardens (HBG) have great potential to provide living genebanks and access for botanical research for many of Hawai'i's rarest plants. The Gardens are comprised of five geographically separate grounds covering 650 acres across Oahu, including a historic urban arboretum, former picnic grounds of Hawaiian royalty, a mid-elevation garden, a large, wet habitat grounds with a reservoir, and even a volcanic crater. HBG's facilities not only provide an ideal habitat for living collections, but our dedicated staff serve as critical resource for protecting individual plants and providing information to our partners and the public. Although I am newly adopted into the botanical garden community as the HBG Horticulturist, I draw on the experience and challenges faced over 14 years of botanical field work with Hawaii's rarest plants with Oahu's Plant Extinction Prevention Program. I am now working with HBG staff and leadership to move the gardens towards an ecosystem conservation approach by which can build larger, ex-situ communities of Hawaiian species by working with my colleagues in the conservation community who specialize in collecting wild propagules as well as cutting edge seed storage and micropropagation technologies. Developing our role to manage living collections of Hawaiian plants will provide a critical resource for these conservation programs and help communicate the value of Hawaii's natural heritage to the public.
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.
Jordan Wood, Jeremie Fant, Andrea Kramer and Kay Havens, Chicago Botanic Garden
Genetics becomes important whenever populations become small (<100). This includes loss o fgenetic diversity from drift, increased expression of deleterious genes due to inbreeding, and limiting local adaptation. Since many species of plants are able to be seed banked, it is possible to maintain numbers well above these critical genetic thresholds. However for exceptional species, which can only be maintained as living plants, or for critically endangered species where remaining individuals are already below these numbers, the need to consider the remaining genetic diversity becomes critical. Importantly, the management focus shifts from saving a population to preserving each genetically unique individual. When you have such small numbers, it is critical to know how each individual contributes to the overall genetic diversity remaining. We are working with National Tropical Botanic Gardens (Hawaiʻi) to develop a multi-institution species management and breeding plan for Ālula(Brighamia insignis)that will ultimately support its restoration to the wild. To do this we are working with scientists at the Chicago Zoological Society to modify management software that incorporates genetics and demography information to maintain the long-term health of their captive populations of animals over the long term. Through this case study, we hope to develop collections management practices for plants that preserve important genetic diversity while identifying genetically appropriate individuals to using in crosses and that can ultimately be used to create resilient populations that can be used in reintroductions.