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.

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.

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.

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.

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.

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.

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.

Seeds are crucial for plant reproduction, dispersal and agriculture. Seed quality and vigour greatly impact crop production by enabling rapid and uniform germination under various environmental conditions. This leads to healthy seedlings that can withstand both biotic and abiotic stresses, which are particularly important in the context of the accentuation of global climate change. Upon imbibition during germination sensu stricto, seeds release exudates, complex mixtures of organic and inorganic molecules, into the microenvironment surrounding them, known as the spermosphere. These exudates play a pivotal role in seedling development and overall plant fitness by influencing microbial selection, growth and interactions in the spermosphere, ultimately shaping the plant's microbiome. Proteins such as enzymes with protection properties have previously been demonstrated to be released by the seeds in their exudates. However, limited information is available pertaining to peptides in seed exudates. Here, we developed an experimental protocol to extract and identify peptides in the spermosphere of germinating common bean seeds. We showed that our methodology was successful in identifying a broad spectrum of peptides and that extraction solvent choice impacts peptide identification both qualitatively and quantitatively. We also show the possibility of using online prediction tools to predict the properties of identified peptides based on their amino acid sequence. We propose that this approach may be used to identify potential molecules that could be used as candidates for developing strategies to enhance seed quality and improve crop productivity.

Seed biopriming with Pseudomonas fluorescens as a beneficial microbial inoculant and seed hydropriming with deionized water were conducted with oilseed rape (Brassica napus). Both techniques involve restricted seed hydration followed by seed drying. Seed biopriming reduced the uniformity (time difference between 10 and 90% germination) of germination ca 4-fold, without changing the maximum germination percentages (Gmax) of seed populations. In contrast to this, seed hydropriming improved the uniformity, but not for aged seed populations. The distinct effect of biopriming on germination was caused by the high salt concentration in the priming medium, not by the bacteria or any of the other components. The effects of biopriming duration, seed input and temperature (incubation and drying) were tested and the number of bacteria attached to the seed coat surface was between 1.6 × 106 and 9.8 × 108 colony-forming units (CFUs) per seed. Long-term storage (21°C, <10% relative humidity, 21% oxygen) of dry bioprimed seeds resulted in a rapid decline of bacterial viability, for example (6 h biopriming, 50 g seed input) from 9.8 × 108 CFU per seed to 7.3 × 104 after 4 weeks and 5.0 × 102 after 12 weeks of air-dry seed storage. Seed biopriming and long-term storage of dry bioprimed seeds did not affect Gmax at optimal (24°C) and cold-stress (16°C) temperatures, and did not appreciably affect early seedling growth. Additive biopriming with kimchi paste did not affect the number of bacteria attached per seed but caused an ~800-fold increase in retaining bacterial viability during long-term seed storage.