Explore the vast range of titles available.

Premise Ex situ seed banking is critical for plant conservation globally, especially for threatened floras in tropical ecosystems like Hawai‘i. Seed bank managers must maximize longevity, and species managers must plan restoration before seeds lose viability. Previous observations suggested some native Hawaiian seeds lost viability in frozen storage (−18°C). We investigated seed storage behavior in the Hawaiian flora to optimize storage conditions and recommend re‐collection intervals (RCI) to maximize viability of stored seeds. Methods Using 20+ years of real‐time seed storage viability data, we tested freeze sensitivity for 197 species and calculated RCIs for 295 species. Using paired tests of accessions stored >2 yr at 5°C and −18°C, we developed an index of relative performance to determine freeze sensitivity. We calculated RCIs at 70% of highest germination (P70). Results We identified four families (Campanulaceae, Cyperaceae, Rubiaceae, and Urticaceae) and four genera with seed freeze sensitivity and six additional genera with likely freeze sensitivity. Storage longevity was variable, but 195 species had viability >70% at the most recent tests (1 to 20+ yr), 123 species had RCIs >10 yr, and 45 species had RCIs <5 yr. Conclusions Freeze sensitive storage behavior is more widely observed in Hawai‘i than any other regional flora, perhaps due to insufficient testing elsewhere. We present a new protocol to test seed freeze sensitivity, which is often not evident until 2–5 years of storage. Re‐collection intervals will guide restoration practices in Hawai‘i, and results inform seed conservation efforts globally, especially tropical and subtropical regions.

Ex situ conservation of orchid seeds requires the application of modern biotechnology to determine seed quality and to optimise in vitro regeneration. The nutrient requirements for germination and seedling growth in vitro can be species-specific and influenced by life history traits and habitats. Therefore, this study aimed to explore in vitro seed germination and subsequent seedling development of selected tropical and temperate epiphytic and terrestrial orchids on different growth media. Seeds of three epiphytic orchids [Dendrobium strebloceras (tropical), D. lineale (tropical) and D. cunninghamii (temperate)] were sown on four different media supplemented with 2% sucrose: (1) Murashige and Skoog (MS); (2) Vacin and Went (VW); (3) Norstog; and (4) water agar. In addition, D. strebloceras seed were sown on the media above supplemented with 3% sucrose and half-strength MS supplemented with either 2% or 3% sucrose. Seed germination of three temperate terrestrial orchids (Gastrodia cunninghamii, Pterostylis banksii and Thelymitra nervosa) was assessed on media (1–4) but with VW replaced by terrestrial orchid medium-BM1. Whilst all epiphytic orchids germinated on all media tested, the best seedling development for the two tropical species was on full or half-strength MS media. The temperate epiphyte D. cunninghamii germinated best on Norstog medium but did not develop further. Norstog and BM1 media supported germination and seedling development better in P. banksii and T. nervosa. This study concludes that temperate terrestrial P. banksii and T. nervosa need more excating media (Norstog and BM1 media) for seed germination and subsequent seedling development compared to tropical epiphytic species D. strebloceras and D. lineale. Optimising these nutrient requirements in vitro will underpin successful ex situ conservation of orchid species.Key messageSeeds of tropical epiphytic orchids, D. strebloceras and D.linelae require a less stringent nutrient medium for in vitro germination and seedling development compared to temperate terrestrial orchids P. banksii and T. nervosa. Understanding the differences in nutrient requirements for germination and subsequent seedling development underpins successful ex situ conservation of orchids.

Stored RNA plays a key role in seed germination, especially after seeds long-term storage. This study aimed to assess the correlation between germination potential (GP) and RNA integrity in common bean ( Phaseolus vulgaris L.) seed accessions stored at -18 °C for 19.25 to 43.75 years and in seeds subjected to artificial aging at high temperature (42 °C) and relative humidity (100%). The GP of long-term preserved and artificially aged seed lots ranged from 3 to 100% and 38–87%, respectively. RNA integrity was evaluated using the RNA Integrity Number (RIN, Agilent Bioanalyzer software). RIN data suggested that: (1) Sample sizes for RIN analysis may need to vary based on the GP of the seeds; (2) RIN has the potential to predict physiological quality, especially in seeds with high GP; (3) RIN values by itself may not accurately reflect the rate of RNA degradation over time, necessitating comparison with a control to determine ΔRIN (the difference between the RIN values of the sample and the control); (4) ΔRIN has a significant positive correlation with GP. These findings highlight the potential of RNA integrity in seeds as a molecular marker for developing tests that complement germination tests.

Abstract Seed (gene)banking is an effective way to conserve cultivated and wild plant diversity. However, long-term funding is not always consistently sufficient, and there is a need to both strengthen the effectiveness of genebank operations and maximize cost efficiency. One way to control the cost of maintaining a germplasm collection is to optimize the quantity of seeds per accession that is placed into storage, depending on the expected length of time a seed lot will remain above the viability threshold, expected rates of use for distribution and viability testing and on the requirement to ensure a reserve. Here, we express this as an equation, which can be applied to cultivated species and adjusted to different scenarios, but also to inform decisions about use of accessions of wild species where the number of seeds available is limited, a common scenario for wild-species conservation seed banks. For many crop genebanks, given the expected longevity of seeds, it would be worthwhile to increase the number of seeds produced and processed for storage. This would also help to diminish the risk of genetic drift due to frequent cycles of regeneration but would have implications in terms of how accessions are regenerated, in particular, how many plants are used for regeneration and the size of storage facilities. The equation we present can also be rearranged and used to plan how to allocate seeds for testing and use when the number of seeds available is limited. This may have particular relevance for species conservation seed banks. Lay Summary To ensure the sustained conservation of plant diversity in seed (gene) banks, it is important to improve the efficiency and effectiveness of operations. Here, we present an equation to determine the optimum quantity of seeds for germplasm storage. Application of this equation has the potential to reduce cycles of seed multiplication.

Seed storage life in tropical areas is shortened by high humidity and temperature and the general inaccessibility to dehumidifying and refrigeration systems, resulting in rapid decreases in seed viability in storage as well as a high incidence of fungal and insect infestations. The dry chain, based on rapid and deep drying of seeds after harvest followed by packaging in moisture-proof containers, has been proposed as an effective method to maintain seed quality during medium-term storage in humid climates, even without refrigeration. In addition, seed drying with zeolite drying beads can be more effective and economical than sun or heated-air drying under these warm, humid conditions. In this paper, we review recent published literature regarding the dry chain, considering different crop species, storage environments and seed traits. In addition, we provide new original data on the application of dry chain methods and their implementation at larger scales in South Asia, Latin America and Pacific Island Countries. The clear conclusion is that the combination of reusable drying beads and waterproof storage containers enables the implementation of the dry chain in tropical climates, enhancing seed viability and quality in storage of many crop species. The dry chain approach can therefore significantly enhance seed security for farmers in many tropical countries. Finally, we propose actions and strategies that could guide further scaling-up implementation of this technology.

Water is essential, irreplaceable, and indispensable for any kind of carbon-based-life metabolic activity. Water-dependent living beings are the expected pattern in nature. However, some organisms can survive for some time at a minimum water content, such as seeds of some species (orthodox seeds). Nevertheless, the expected standard life behavior is found in seeds of another group of species, the so-called recalcitrant seeds, which are sensitive to desiccation. A huge range of different behaviors can be found between these two groups, leading authors to consider that orthodoxy and recalcitrance is not an all-or-nothing situation. Notwithstanding, we are still too far from understanding the differences and similarities between all these kinds of seeds and this has been a serious barrier to the development of plant conservation technologies. A new approach to understanding the differences between these seeds is presented here based on seed maturation, environmental influences, and evolution. From this point of view, all kinds of seed behavior are contemplated and, consequently, some new perspectives are considered for the recalcitrant seed conservation technology, the most intensely desired technology nowadays in this area. RESUMO: A água é essencial, insubstituível e indispensável para qualquer tipo de atividade metabólica da vida baseada no carbono. A dependência dos seres vivos por água é o padrão esperado na natureza. No entanto, alguns organismos podem sobreviver por algum tempo com um teor mínimo de água, como sementes de algumas espécies (sementes ortodoxas). No entanto, o comportamento padrão de vida esperado é encontrado em sementes de outro grupo de espécies, as chamadas sementes recalcitrantes, que são sensíveis à dessecação. Entre esses dois grupos há uma enorme variedade de comportamentos diferentes que levaram autores a considerar que a ortodoxia e a recalcitrância não são uma situação de tudo ou nada. Não obstante, ainda estamos muito longe do entendimento das diferenças e semelhanças entre todos esses tipos de sementes e isso tem sido um sério entrave para o desenvolvimento de tecnologias de conservação de plantas. Aqui, uma nova abordagem para entender as diferenças entre essas sementes é apresentada tendo como base a maturação de sementes, as influências ambientais e a evolução. Sob este ponto de vista, todo o tipo de comportamento das sementes é contemplado e, consequentemente, são consideradas algumas novas perspectivas para a tecnologia de conservação de sementes recalcitrantes, que é a mais intensamente desejada hoje em dia nesta área.

The contribution of the European Native Seed Conservation Network (ENSCONET, 2004-2009) and the ENSCONET Consortium (since 2010) towards meeting the 2020 Global Strategy for Plant Conservation (GSPC) target 8 was assessed in 2017. While the outcome was positive (62.7% of European threatened species already conserved ex situ in seed banks), the analysis showed that it was essential to provide guidance on which European native threatened species should be collected as a priority if the target was to be reached by 2020. In this paper we present a priority-setting method and its result, designed to guide collecting strategies across Europe to meet the 2020 GSPC target 8. The result of our study is a country-based checklist of European threatened taxa to be collected and stored ex situ across the seed banks of the ENSCONET Consortium by 2020. After discussing the results of the applied method, the ENSCONET Consortium Steering Committee has identified some key action points to support the implementation of such a collecting strategy across Europe in order to meet the 2020 GSPC target 8 for Europe.

Seed longevity influences the success of ex situ storage and preservation of plant genetic diversity and is thus a critical factor in conservation efforts. Rapid seed ageing experiments at high temperature and high humidity have been widely used to classify seed longevity for hundreds of plant species, with potential implications for longevity in ex situ conservation. In this approach, radicle emergence (R) is normally used as a measure of the viability of the seeds. However, R could overestimate the level of normal seedling development and, consequently, the perceived longevity of seeds. Here, seed lifespan for 33 alpine species was compared to assess whether germination criteria could affect seed longevity parameters. Seeds were exposed to controlled ageing [45°C, 60% relative humidity (RH)] and regularly sampled for germination assessment as both radicle emergence (R) and radicle plus cotyledon emergence (R + C). The time taken in storage for viability to fall to 50% ( p 50 ) was determined using probit analysis, including either R or R + C data. A coefficient of overestimation of seed longevity (OESL, %) was determined. The results highlight significant differences in seed longevity estimates both across species and the germination criteria. For 17 species, seed longevity estimated by R was significantly higher than that estimated using R + C, resulting in large variation in OESL (0.54–9.01 d). The introduction of OESL facilitates effective screening for seed longevity and recovery, enhancing the overall efficiency of conservation strategies for diverse species.