Seed banking is the preferred strategy for the ex situ conservation of Seed Plants, due to its effectiveness in preserving whole organisms and genetic diversity at relatively low cost. However, not all seeds are suitable for long-term storage, particularly those classified as recalcitrant or desiccation-sensitive, which limits the applicability of seed banking for certain species. In Chile, the proportion and identification of recalcitrant species remain largely unknown. In this study, we investigated the storage behaviour of potentially recalcitrant species and evaluated two predictive models of seed recalcitrance based on morphological, ecological and taxonomic variables. One of these models was subsequently employed to estimate the incidence of recalcitrance among Chilean tree species. Most of the species assessed exhibited clear sensitivity to desiccation. The Seed Coat Ratio–Seed Mass model showed the highest precision and recall. Nevertheless, models incorporating ecological and taxonomic variables also performed well at the genus level. Using a Boosted Regression Tree model refined through experimental data and literature review, we estimate that 19% (n = 11) of Chilean tree species possess recalcitrant seeds. Among the tree and shrub species confirmed as recalcitrant in this study (n = 17), 71% are endemic to Chile (n = 12), and 53% are categorized as threatened (n = 9). These findings provide a stronger basis for prioritizing alternative ex situ conservation strategies beyond seed banking for species with recalcitrant seeds.

The previous study indicated that ubiquitination is involved in the freezing tolerance of hydrated seeds. Parthenolide (PN), inducing the ubiquitination of MDM2, an E3 ring-finger ubiquitin ligase, adversely affects the freezing tolerance of hydrated lettuce seeds. Therefore, a proteomics analysis was conducted to identify PN's targets in hydrated seeds exposed to cooling conditions. Several pathways, including oxidative phosphorylation (KEGG00190), amino sugar and nucleotide sugar metabolism (KEGG00520), and biosynthesis of nucleotide sugars (KEGG01250), were enriched in the PN treatment under slow-cooling conditions (3°C h−1, P < 0.05). Among the proteins in oxidative phosphorylation, the expression of NADH dehydrogenases and ATP synthases (ATPsyn) decreased in PN treatment. In contrast, uncoupling proteins increased after PN treatment, which led to the dissociation of the electron transport chain from ATP synthesis. Treatments with rotenone, dicoumarol, and oligomycin (i.e., oxidative phosphorylation inhibitors) decreased the survival rate of hydrated seeds under freezing conditions, which indicated that energy metabolism was related to the freezing tolerance of hydrated seeds. The predicted interactions between PN and MDM2-like proteins of Lactuca indicated that LsMDM2-5 forms two potential hydrogen bonds with PN. Furthermore, based on AlphaFold predictions and yeast 2-hybrid results, MDM2-5 might interact directly with NADH2. The knockdown of MDM2-5 by RNAi caused a higher level of NADH2 and ATPsyn and a higher freezing tolerance of hydrated seeds. This indicated that MDM2 played negative roles in regulating ATP synthesis and freezing tolerance of hydrated seeds.

The classification of acacias has gone through recent upheaval. The latest phylogenies indicate that Acacia sensu stricto is only relatively distantly related to the species with which it was once grouped. Its sister group is the monospecific Paraserianthes. This study concerns P. lophantha subsp. lophantha, a species from SW Western Australia that is widely invasive. Both genera have seeds with physical dormancy (PY) and a lens-type water gap. Seed structure, particularly that of the lens, was assessed in Paraserianthes and compared with Acacia. Seed batch viability was almost 100%, all seeds had PY and average seed mass was 73 mg. The seed coat and the embryo made almost equal contributions to seed mass, indicating a substantial seed coat. Average testa (410 µm) and palisade layer (163 µm) thicknesses were greater than in most investigated Acacia species. Unpopped lenses were small (0.11 mm2, about 0.15% of the seed surface area). With a 1 min boiling water treatment, the lens detached from the seeds. The palisade cells of the lens were about 100% larger in area after detaching, which indicates that they previously were under considerable tension. With other PY-breaking treatments, the lens formed a mound or a slight change in colour occurred. The seeds of Paraserianthes lophantha had the same basic construction as most Acacia seeds, although they were relatively large and heavy, the testa made up a large proportion of the seed and the palisade cells were long. Different lens morphologies, associated with different dormancy-breaking treatments, have rarely been described.

The genetic basis of rapid and uniform seed germination and its associated traits is crucial for improving seed vigour and seedling establishment for higher productivity in direct-seeded rice (DSR) systems. This study investigates the phenotypic diversity and genetic architecture of germination traits in 163 rice genotypes, using a genome-wide association studies (GWAS). An association panel of 163 diverse rice genotypes, including varieties, germplasm and breeding lines, was evaluated for seed germination traits over 2 years (2022 and 2023). The panel was genotyped using 295 simple sequence repeat (SSR) markers, including 80 random SSRs and 215 candidate gene SSRs linked to seed traits and morphological attributes. The genotyping of 163 lines with 295 markers revealed a range of genetic diversity, with polymorphic information content values between 0.04 and 0.93. Population structure analysis indicated the presence of two groups and four sub-groups. GWAS identified 80 significant marker-trait associations (MTAs) across 12 chromosomes at P ≤ 0.05, which narrow down to 18 MTAs at P ≤ 0.01. Twelve candidate genes are identified which were related with multiple traits, linked to important functions, such as seed-size regulation, nutrient mobilization and plant growth. Candidate gene-based SSR (cgSSR) markers such as M169 (OsMIK), M57 (THIS1), M66 (GW2), and M18 (OsBAK1), displayed pleiotropy including rapid and uniform germination (germination index, germination rate index and mean germination time) traits. The newly identified candidate gene markers associated with seed rapid and uniform germination traits can be leveraged in marker-assisted breeding programs to introduce diverse alleles for enhanced seed vigour and crop establishment. Markers closely linked to multiple traits hold significant potential for the simultaneous improvement of several traits.

Seeds are complex structures that serve as dispersal units in angiosperms. Seeds consist of three specialized tissues with distinct roles and molecular compositions. Hence, the characterization of the genetic regulators that act within individual seed tissues, and how their activity changes during seed development and germination, has been a primary focus of seed research. However, our knowledge of the spatiotemporal modulation of genetic regulators within seeds, across different seed cell types, has been limited by the resolution of available techniques. In the last few years, the development and application of single-cell technologies in plants have enabled the elucidation of gene networks involved in various developmental processes at the cellular level. Some studies have applied these technologies to seeds, enabling further characterization of seed development and germination at the cellular level. Here, we review the current status of the application of single-cell technologies to seeds and present a workflow for conducting single-cell transcriptomics. Additionally, we discuss the integration of single-cell multi-omics, aiming to demonstrate the potential of single-cell technologies in enhancing our comprehension of the spatiotemporal regulations governing seed development and germination.

The Myrtaceae is the ninth largest angiosperm family with c. 6000 species, and it diverged from its closest relative the Vochysiaceae c. 100 Ma in southern Gondwana before the final separation of South America and Australia from Antarctica. The family has trees and shrubs and a few viny epiphytes but no herbs and mainly occurs in the tropics and in temperate regions with a Mediterranean climate. Numerous fleshy-fruited species and dry-fruited species have evolved in moist and seasonally dry (fire-prone) regions, respectively. Five kinds of fully developed embryos are found in Myrtaceae seeds, and at maturity seeds are either nondormant (ND) or have physiological dormancy, regardless of embryo morphology, kind of fruit produced, life form, habitat/vegetation region or tribe. Dormant seeds of fleshy-fruited species in wet habitats become ND and germinate at high temperatures. Dormant seeds of dry-fruited species in seasonally dry habitats become ND during the hot, dry season and germinate with the onset of the wet season; seeds germinate only at high temperatures or over a range of low to high temperatures, depending on the species. Seeds of fleshy-fruited species are animal-dispersed, and some Myrteae and Syzygieae are desiccation-sensitive and/or exhibit totipotency. Relatively few species form a persistent soil seed bank, but many dry-fruited species in fire-prone habitats form an aerial seed bank (serotiny). Heat and smoke from fires have a negative, neutral or positive effect on germination, depending on the species. Challenges for maintaining the high species richness of Myrtaceae include habitat destruction/fragmentation, pathogenic fungi and climate change, especially patterns of precipitation.

Healthy seeds are an important component of global food security, and their microbiome was recently identified as crucial for plant growth, resilience and health. Seed vigour is highly affected by storage conditions and aging. To study the impact of seed aging on the Brassica napus seed bacterial community, we conducted accelerated aging tests (45°C, humidity > 95%) with seed lots of four genotypes originating from two field sites in Germany. We found a strong effect of accelerated aging on germination, seedling phenotypes, as well as the seed bacterial community. Control seeds developed mainly into normal seedlings and were characterized by diverse bacterial communities comprising typical core seed microbes. Accelerated aging resulted in abnormal germination and reduced total germination. Furthermore, accelerated aging reduced diversity and evenness of the seed bacterial community and contributed to a shift from Gram-negative to Gram-positive bacteria. This effect, especially the enrichment of Firmicutes, was found irrespective of the genotype and field site; however, the way stress affected bacterial taxa varied, depended on both factors. Tumebacillus and Bacillus showed a significant negative correlation with germination phenotype, whereas alpha diversity correlated positively with a high total germination. At the functional level, the majority of isolated bacteria demonstrated plant-beneficial characteristics, showing a greater beneficial potential in the aged seeds. Our results show that accelerated aging tests affect the seed bacterial community structure and diversity, and correlate with the presence of certain taxa, which might have an effect on germination and seedling phenotype.

Developing cereal seeds contain photosynthetically active cells in the form of a thin green layer, the chlorenchyma, which surrounds the non-photosynthetic endosperm. The current understanding is that the chlorenchyma primarily supports endosperm respiration by supplying oxygen. However, despite the importance of such a function, photosynthetic electron transport is still poorly understood and would benefit from detailed study. This represents a technical challenge as bulky developing seeds are unsuitable for the classical spectroscopic methods routinely used for leaf material. In this study, we established a method that enables simultaneous measurement of photosystem I and photosystem II activities in dissected barley chlorenchymas with pulse amplitude modulation spectroscopy and also adapted it to measure electron transport with the electrochromic band shift. Comparative analyses of raw spectral signals and derived parameters measured on chlorenchymas and leaves demonstrate that this approach provides a reliable and detailed assessment of chlorenchyma photosynthesis. Establishing this method provides a new framework for investigating the physiological relevance of electron transport and carbon assimilation in non-foliar tissues such as chlorenchymas.

The seed science community currently defines germination as radicle emergence of 2 mm from the dispersal unit. Consequently, most seed researchers abruptly terminate germination experiments after radicle emergence, concluding that the seed has germinated. However, this approach underestimates epicotyl dormancy and often leads to dormancy misclassification, or worse, a failure to identify epicotyl dormancy altogether. To address these limitations, we propose extending germination studies to the point of first leaf emergence; we term this the “full germination” period. Our methodology involves germinating fully matured, freshly collected seeds and depending on the time required for radicle emergence, the seeds are categorized into (1) viviparous, where seeds germinate prematurely while they are still attached to the parent plant or within the fruit; (2) Morphological dormancy (MD) or Non-dormant (ND), where seeds germinate within 30 days; and (3) physiological dormancy (PD) and morphophysiological dormancy (MPD), where germination does not occur within 30 days. The absence of shoot emergence within 30 days following radicle protrusion indicates the presence of epicotyl dormancy. Thus, species initially classified as ND, MD, or viviparous may be miscategorized if shoot emergence is not assessed. Likewise, seeds exhibiting PD or MPD may possess an additional epicotyl dormancy component, possibly leading to placing them in incorrect subclass or level. A comprehensive assessment of shoot development is imperative for accurate dormancy characterization. We strongly recommend monitoring seed germination until first true leaf emergence should be adopted to ensure correct conclusions about dormancy, plant life cycles and ecological adaptations.

Leonurus cardiaca is a perennial mint species with a long history of use as a medicinal herb. It produces a wide variety of phytochemicals with pharmacological properties that are used to treat anxiety and sleep disorders, cardiac disorders, and to reduce inflammation. Surprisingly, scant information is available concerning its seed germination ecology. Hence, this study investigated the presence/kind of seed dormancy and the effects of several environmental factors on seed germination and seedling emergence. Seeds were collected from three populations, and they were subjected to germination and seedling emergence experiments in which environmental factors, including temperature, light, cold stratification, pH, osmotic stress, and depth of burial, were manipulated. Non-stratified seeds germinated over a range of alternating temperature regimes from 20/10 to 30/20°C, but they did not germinate at 15/5°C. Optimum germination occurred between 25/15 and 30/20°C. The presence or absence of light did not affect germination. Cold stratification at 4°C enhanced germination at the two coolest temperature regimes. Seed germination occurred over a solution pH range of 5–10 and exceeded 55% in buffer solutions with pH 6–10. Low levels of osmotic stress reduced germination; only 3–8% of seeds germinated at −0.2 MPa. Maximum seedling emergence occurred when seeds were placed on the soil surface, and emergence decreased with increased burial depths to 5 cm. Overall, seeds exhibited germination characteristics associated with type 2 non-deep physiological dormancy at maturity. Seeds primarily germinated at incubation temperatures of ≥ 25/15°C; however, conditionally dormant seeds became nondormant after prolonged exposure to cold stratification.

Cumin (Cuminum cyminum L.) is an annual herbaceous plant from the Apiaceae family, renowned for its medicinal and culinary applications as the second most popular spice globally after black pepper. Germination is a critical stage in the life cycle of plants, particularly for medicinal plants, as it determines successful establishment and productivity. This study explores the impact of ploidy levels (diploid and tetraploid) and genotype interactions on germination traits, seed morphology and early seedling growth in five selected cumin genotypes (YAR1, KBA4, SKD6, SIV8 and NKM9). Induction of tetraploidy significantly influenced germination percentage, rate, seed vigour index, and morphological traits. Notably, diploid genotypes exhibited higher germination percentages, while tetraploid SKD6 displayed the highest germination speed and seedling biomass, demonstrating genotype-specific ploidy effects. For the first time, root growth kinetics were analyzed, revealing distinct growth patterns between diploid and tetraploid seeds. Morphometric evaluations showed that tetraploid seeds and embryos were significantly larger, attributed to the ‘gigas effect’, which enhances storage reserves and seed vigour. However, challenges such as embryo-less seeds and variability in genotype responses to ploidy manipulation were observed. These findings underscore the importance of targeted breeding strategies that optimize genotype-ploidy interactions to improve seed quality, germination performance and early growth in cumin. By advancing our understanding of polyploidy’s role in shaping key agronomic traits, this study provides a foundation for sustainable cultivation practices and enhanced productivity of medicinal plants.

Endozoochory, the dispersal of seeds through the animal gut passage, plays a significant role in vegetation dynamics. The success of endozoochorous seed dispersal depends on each stage of the process: ingestion by animals, gut passage, and post-dispersal events after defecation. After the deposition of seeds through feces, the effects of feces on the initial stages of seedling establishment, including seed germination and seedling growth, can significantly impact overall survival. The pattern of fecal effects on plant species depends on the animal species. In this study, we investigated the effects of feces presence on seed germination and early seedling growth using feces of the Korean water deer (Hydropotes inermis argyropus). We conducted a germination experiment on 12 plant species belonging to 10 plant families, which are known to germinate in the feces of Korean water deer. The study compared the seed germination rate and seedling length after germination between seeds sown with and without feces of the Korean water deer. In general, we found that the presence of deer feces per se had no significant effects on seed germination and early growth stages. However, additional research on post-dispersal events such as long-term growth, fecal type, and germination conditions is needed to fully understand the costs and benefits of endozoochory.

Seed dormancy is the key factor determining weed emergence patterns in the field. Alopecurus myosuroides (black grass) is a serious cereal weed in Europe that experiences two emergence peaks affecting winter and spring cereals, respectively. Seedlings that emerge in autumn encounter a period of cold winter temperatures, whereas those that emerge in spring do not. In this work, we investigated the effects of this overwintering during vegetative growth on the primary seed dormancy of the offspring. Alopecurus myosuroides plants were propagated under controlled conditions where a proportion of the population was subjected to a simulated winter period (vernalization) as seedlings. The offspring produced by vernalized plants was significantly more dormant, requiring longer after-ripening and cold stratification treatments to germinate at warm temperatures. However, there was no difference in the range of temperatures under which dormant seeds germinated. We hypothesized that this difference in dormancy was the result of an epigenetic memory of vernalization. Global changes in DNA methylation of seeds were quantified using an ELISA-based approach. Imbibition in dormant seeds produced by vernalized plants was associated with a global demethylation event that was not observed in the offspring of plants that had not been vernalized. Taken together, these results demonstrate the importance of temperature at different stages of the plant lifecycle in determining dormancy levels and consequently weed emergence patterns in the field.

Variation in orchid seed size and shape can be linked to phylogenetic relationships, habitat preferences, germination behaviour or dispersal strategies. To investigate this, we compared 45 orchid species from 29 genera collected across different localities in Cameroon using optical microscopy. We categorized each species according to lifeform (38 epiphytic vs. 7 terrestrial), altitudinal range (11 mountain vs. 34 lowland) and geographic distribution (28 widespread vs. 17 range-restricted). We analysed seed morphology using phylogenetic signal tests, analysis of variance and principal component analysis. Our results confirm a clear distinction between epiphytic and terrestrial species, with intermediate morphologies observed in genera encompassing species with both lifeforms (Cynorkis, Graphorkis, Habenaria and Liparis). Certain traits, such as seed length and seed air space, show a strong phylogenetic signal, suggesting that these traits are more linked to ancient evolutionary history than to recent ecological adaptation. Among the 38 epiphytic species, no consistent relations were found between seed traits and either geographic range or altitudinal distribution. Our findings suggest that the variation observed in seed morphology among African orchids is influenced more by phylogenetic relationships than by present-day distribution.

Seed respiration is a key metabolic process linked to physiological status. Q2 respiration analysis enables detailed profiling of individual seeds, and combined with multispectral imaging, allows to explore seed-to-seed relationships between respiration and spectral or morphological traits. Thus,the study aims to investigate the relationship between the respiration profiles of individual soybean seeds and their morphological and spectral characteristics, using single-seed respiration analysis and multispectral imaging. Multispectral images were captured from 1,808 seeds using the VideometerLab system, from which 75 features were extracted. The seeds were placed in vials with 0.4% (w/v) agar to induce germination and sealed with caps containing a fluorescent polymer dot. The Q2 analyzer, tracked the oxygen consumption of each seed during germination. Both the VideometerLab and Q2 analyzer data were categorized through hierarchical clustering, and a subpopulation of seeds was selected from three categories of respiration profiles due to computational limitations. The association between respiration patterns and biometric features was analyzed using contingency tables and entropy analysis. The results revealed significant differences in respiration patterns, particularly in autofluorescence excitation-emission at 365/600, 430/700, 450/700 and 470/700 nm, as well as in reflectance at 365, 690 and 405 nm. Notably, 75% of seeds with similar respiration profiles were grouped based on similarities in their biometric characteristics, suggesting a relationship between respiration patterns and biometric features. Additionally, patterns of certain biometric traits indicated that different combinations can lead to similar respiration profiles, highlighting the complexity of evaluating this association.

Physical dormancy (PY), resulting from a water-impermeable seed coat, regulates germination timing in many angiosperms, including Dodonaea viscosa L. (Sapindaceae), a woody shrub widely distributed in tropical to warm temperate regions and coastal and inland habitats. Although PY has been previously documented in D. viscosa, the precise anatomical structure acting as the site for water entry, i.e., water gap, during dormancy release remains unclear. This study investigated the water gap’s morphology and function using microscopy, scanning electron microscopy (SEM) and imbibition assays. It also evaluate the effects of liquid nitrogen (LN₂) freeze–thaw cycles on seed coat integrity, dormancy break, and viability. Seeds possess a distinct hilar slit, which opens in response to hot-water treatment and serves as the exclusive water gap. Imbibition experiments showed that treated seeds (hot water , 10s) increased nearly 100% in mass over seven days, while control seeds absorbed no water. Further, covering the hilar slit with Vaseline restricted water uptake, confirming the absence of water-gap complex. Because the water gap opening was a small circular structure without any lid-like covering, it is classified as Type II. Seeds subjected to one or more liquid nitrogen (LN₂) freeze–thaw cycles experienced extensive seed coat cracking and severe damage to the embryo and cotyledons, leading to reduced viability and little to no germination. These findings demonstrate that while hot-water treatment effectively breaks dormancy, LN₂ exposure causes extensive mechanical injury and is ineffective for dormancy alleviation in D. viscosa. Thus, cryopreservation of some PY should be considered with caution.

For many decades, seed germination data have been modelled by probit analysis. In particular, it is the basis of the seed viability equation used, in the first instance, to describe the decline in germination of seeds in storage, but then also the rate of the decline, depending on seed moisture content and the temperature of storage. The underlying assumption of a probit model is that the response follows a normal distribution, in this case, loss of the ability to germinate over time. Probit analysis also takes into account the binomial error associated with germination data. Many statistical packages have probit analysis as an option within the generalized linear modelling framework; here, we present code for applying probit analysis in the free software, R. Codes are provided for fitting a single survival curve, for a single seed lot stored in a constant storage environment; for fitting multiple survival curves and evaluating the effect of constraining parameters for the different seed lots; and lastly, to model the moisture relations of seed longevity. The code bases provided could also be used in pollen and fern/bryophyte spore longevity modelling.

The Malvaceae is the 12th largest angiosperm family with ten subfamilies, 243 genera and c. 4000 species of trees, shrubs, herbs and a few climbers. Subfamilies originated in the Upper Cretaceous-Palaeocene, and their divergence times range from 71.6 to 33.0 Ma. Seeds have a folded, investing or spatulate embryo, and they may be nondormant (ND) or have physical (PY) and/or physiological (PD) dormancy. Of the 365 species for which dormancy/germination data were found, 34.0% had ND seeds and 46.6% PY; 1.6%, PD&ND; 13.1%, PY&ND; and 4.7% PY+PD. Seeds with PY have a palisade layer of Malpighian cells (with a light line) in the outer epidermis of the inner integument, and a chalazal plug is the water gap. Seeds of 168 species of wet tropical trees, in all ten subfamilies, were ND (57.2%) or had PY (19.7%), but seed collections of many species were a mixture of ND & PY (20.2%); 2.9% had PD&ND. We found 13 tree species in wet tropics with recalcitrant seeds and 57 species in 28 genera in seven subfamilies in various habitats with persistent soil seed banks. Malvoideae is the most species rich and widely distributed subfamily and is found in tropical and temperate regions but rarely in subalpine/boreal or Arctic/alpine tundra vegetation. Few if any Malvaceae, in particular Malvoideae, grow as herbaceous perennials in tundra vegetation; possible reasons for this are considered.

Seed persistence, desiccation tolerance, and dormancy play a crucial role in plant population and community dynamics. However, these life-history traits remain largely understudied in perennial herbaceous species, particularly in tropical ecosystems. We evaluated the seed storage behaviour, potential longevity, soil seed bank, seed dormancy alleviation in the field and the effects of after-ripening temperature and time on seed dormancy alleviation in Carajasia cangae – an endangered perennial forb endemic to the ironstone outcrops of the Eastern Amazon. We performed germination experiments to examine the effect of storage conditions (−20, 5 and 28°C, as well as field storage) and time on seed viability, mean germination time and percentage. Our results suggested that C. cangae seeds form a transient soil seed bank and show orthodox storage behaviour. The seeds' longevity was favoured in all controlled storage conditions in relation to soil-stored seeds (field). However, the marked loss of seed viability in less than 1 year, regardless of storage condition, indicates a low potential for long-term germplasm conservation through seed banking. Seed dormancy was fully alleviated after 3 months of field storage during the dry season. Moreover, seeds stored for 6 months at 28°C had their dormancy partially alleviated, indicating that environmental conditions found throughout the dry season in the species habitat are required to alleviate its seed dormancy. A transient seed bank type is favoured by predictable seasonal variations in climate in the region, species iteroparity and seed dormancy alleviation during the dry season, which delays germination until the onset of the next rainy season.