European gorse (Ulex europaeus L.) is a spiny shrub that grows spontaneously in the understorey of forests and heathlands in western Europe. Gorse is a pioneer species and forms large seed banks that can persist for a long time while buried deeply in the soil. Although many studies have been conducted on gorse seed banks in invasive contexts and in scrubland ecosystems, few data are available on forests in a native context. The aim of the present study was thus to report on the variability of seed-bank density in ‘critical’ stages in the forest management of pine stands (five stands) in south-western France. We examined variations in the number of gorse seeds as a function of soil depth but also of the presence and abundance of adult gorse in the understorey. Seed-bank density did not show a clear decrease in seed number with pine stand age, principally because gorse also appears to be able to establish itself in mature pine stands, probably thanks to local disturbances. In the pine stands in our study, the presence and abundance of seeds in the soil appeared to depend mostly on the presence of adult gorse as seeders in the understorey. Finally, we observed that, contrary to what has generally been found in scrubland ecosystems, most gorse seeds were located in the 5–10 cm soil layer rather than in the 0–5 cm soil layer. This depletion of the first 5 cm may be linked to seed germination that was not compensated for by the production of new seeds.

The ripening rice (Oryza sativa L.) caryopsis contains several maternal and embryonic tissues that transport assimilates along the partitioning pathway. Experimental access to transport steps in the pathway is limited by the separability of the tissues. Hence, the extent to which tissues can be mechanically and enzymatically separated was assessed. The caryopsis coat was isolated during mid-ripening, dissected and microscopically characterized. In centripetal order, the pericarp (epidermis, parenchyma-cell layer, cross-cell layer, tube-cell layer), inner integument, nucellar epidermis, aleurone layer and subaleurone layer adhered to each other. There was mechanical separation at the tube-cell layer, but not at the maternal/embryonic interface. Aleurone- and subaleurone-layer cells exposed on the inner surface of isolated caryopsis coats were macerated with Pectolyase Y-23 and manually sheared, which freed the endosperm and exposed the nucellar epidermis. Yield of endosperm cells increased linearly with the number of coats and reached a maximum after 1 h. The proportion of cells that were viable was approximately 10%. Subaleurone-layer cells contributed less than 25% to the yield. These results suggest that pectin polymers are necessary for adherence between the nucellar epidermis and the aleurone layer, and that enzymatic maceration is useful for separating the tissues at the maternal/embryonic interface.

In imbibing seeds, resumption of metabolism leads to the unavoidable release of volatile by-products that are perceived as cues by rodent seed predators. The crypsis hypothesis proposes that the primary function of a water-impermeable, hard seed coat is to reduce rodent seed predation by rendering seeds olfactorily cryptic. In an opinion paper, Jayasuriya et al. (2015) find the crypsis hypothesis unscientific and ‘not consistent with Darwin's theory of evolution by natural selection’. It is unfortunate that Jayasuriya et al. (2015) did not appreciate that the crypsis hypothesis offers an alternative explanation for the evolution of water-impermeable seeds: released seed volatiles are cues used by rodents to locate seeds, and variation in seed-coat permeability leading to differences in seed volatile release represents the variable under selection. Furthermore, the sealing of water-impermeable seed coats imposes a cost of increased generation time and, therefore, dormancy-release mechanisms are expected to subsequently evolve in response to local environmental conditions. We also disagree with most other claims by Jayasuriya et al. (2015), who failed to appreciate how species with dimorphic seeds – one morph with permeable and the other with impermeable seed coats – benefit from rodent caching behaviour and population dynamics. We welcome this opportunity to clarify and elaborate on key features and the evolution of water-impermeable seed coats according to the crypsis hypothesis.

Protein synthesis in embryonic axes of Norway maple (Acer platanoides) was studied in seeds stratified at 3 or 15°C. At 3°C stratification, germination of seeds started between 6 and 7 weeks; at 15°C stratification germination did not occur. During imbibition of embryonic axes undergoing cold and warm stratification many new proteins became visible. Two of these proteins may be connected with the release from dormancy at 3°C. In seeds stratified at 15°C, these proteins occur in low amounts or are completely absent.

A computer-aided comparison of tomato (Lycopersicon esculentum Mill.) seed protein patterns, obtained after two-dimensional gel electrophoresis, was made for three different extraction procedures: TCA acetone/lysis buffer, lysis buffer only and modified Laemmli/lysis buffer. Comparison of the isolation methods showed that about half of the amount of proteins detected was common in each method. Also, proteins specific to some isolation methods were detected. Protein synthesis during imbibition was monitored using 35S-methionine. After labelling the proteins were extracted using TCA acetone/lysis buffer. Following two-dimensional gel electrophoresis the gels were first silver stained, to give a general picture of all proteins present in the seed, then the gels were exposed to a film for autoradiography. Comparison of the in vivo-synthesized protein patterns and the silver-stained proteins revealed that from day 0 to day 1 the protein pattern was changed but the total number of different spots was similar. After 1 day of imbibition, the number of protein spots increased greatly and the protein pattern changed again.

Identification of discrete stages during embryogenesis is important for the consistent and repeatable selection of seeds having similar developmental characteristics. A timetable for staging developing seeds of alfalfa (Medicago sativa L.) has been developed. Morphological characteristics, fresh and dry weights, SDSpolyacrylamide gel electrophoretic protein patterns and total protein content were recorded at various times between fertilization and 36 d after pollination (maturity), stages I–IX. A full complement of storage proteins (2S, 7S, 11S) is synthesized in both developing cotyledons and radicles. Low-salt soluble (S1) and high-salt soluble (S2) storage proteins first appear during embryo elongation. The proportional amounts of some S1 storage proteins change during alfalfa seed development. Markers are thus provided as uniform reference points for staging from the time of anthesis to seed shedding.

Seeds are notoriously high in polyphenols and polysaccharides, which reduce RNA quality and yield, and interfere with downstream applications. We present simple modifications to a rapid RNA extraction protocol for use with seeds. The inclusion of polyethylene glycol in place of polyvinylpyrrolidone reduced polyphenol and polysaccharide contamination. In addition, replacing NaCl with KCl improved the RNA yield from Arabidopsis seeds still bound by mucilage. On extraction of Arabidopsis seed recovered from field soils clean RNA pellets with no accompanying gelatinous matrix (polysaccharide) were seen, with A260/230 ratios greater than 1.8 confirming the lack of polysaccharide carry-over. When Brassica oleracea and Sinapis arvensis seeds were extracted, 260/230 ratios greater than 1.8 were seen. RNA yields in excess of 10 µg per 100 mg seed suitable for RT-QPCR were obtained.

Helianthinins are storage proteins present in Helianthus annuus seeds, belonging to the 11S globulin family. Here we describe that a fraction of the helianthinins is phosphorylated. This conclusion is supported by different criteria, including identification by matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry of major protein bands revealed with a specific dye for phosphoproteins, anti-phosphoserine antibody and binding to a phosphoprotein affinity matrix. Moreover, we show that the phosphorylation status of helianthinins changes following germination.

Adaptive plastic responses in invasive species allow for establishment and persistence despite the lack of genetic matching to new environments. The capacity of annual species to invade habitats to which they are not adapted is likely to be predicated on post-invasion seed trait variation correlated with conditions in the new habitat. To test this, I compared variation in seed traits and germination patterns of Aegilops triuncialis, an invasive annual grass, from 69 sample populations from 24 sites in California (USA) across 13 years. Seed mass, germination fractions, seed viability, and strength of induced dormancy between dimorphic seed pairs were used to investigate plastic variation within and among populations, across two general soil types, and among two widespread maternal genotypes. I found that seed mass variation was constrained although both seed types showed a 3-fold range among populations, 20–25% variation within populations between years, and was positively correlated with longer growing seasons. However, induced seed dormancy in the small seed type was correlated with large seed mass and to late-season precipitation, suggesting that longer growing seasons influence the strength of maternal and sibling chemical signals that induce dormancy in the small seeds. Thus variation in small seed germination fractions varies with the growing conditions experienced by the maternal plant. The greater longevity of the small seed type suggests that plasticity in germination in this species may contribute to seed bank formation, which is atypical of invasive annual grasses in California, and this may contribute to the persistence and spread of A. triuncialis in invaded ranges.

The developmental pattern of biotinylated proteins (BP) during embryogenesis and maturation of soybean seed was characterized. Detection of these BP was compared with the development of desiccation tolerance in seeds. Three groups of BP were detected in soybean seeds using a biotin-streptavidin detection method: the first group consisted of a set of three bands with a mean apparent MW of 85 kDa (called BP85), detected in crude extracts of embryonic axes (EA) from non-dehydrated seeds (NDS) and from artificially slow-dehydrated seeds (DS); the second one, BP75, was a single protein with an apparent MW of 75 kDa and was expressed in cotyledons (COT) and EA tissues of NDS and DS; the third group with a mean apparent MW of 35 kDa (BP35), was expressed at high levels only in COT of NDS. BP35 concentration was highest in the early stages of seed development (21 days after flowering — DAF) and decreased as seeds developed, being almost imperceptible after 47 DAF. Conversely, only traces of BP75 and BP85 extracted from EA and COT were detected at early stages of seed development (21–33 DAF). Maximum levels of accumulation of these proteins were expressed at 42–47 DAF and remained constant until harvest maturity. Desiccation-tolerant stage of the seeds was initiated at 47 DAF, which coincided with the stage of maximum accumulation of BP75 and BP85 in the seeds, however, appearance of these proteins could be stimulated by desiccation of immature seeds that had not achieved desiccation tolerance. Therefore changes in biotinylated proteins are coincident with, but not sufficient for, the development of desiccation tolerance.

Submerging Phaseolus vulgaris cv. Top Crop seeds in air-saturated water for 16 h markedly depresses subsequent germination. This is termed soaking injury. Soaking injury does not occur in seeds soaked in CO2-saturated water. Previous studies have shown that soaking injury can be alleviated by drying seeds or removing seed coats. Submergence therefore leads to a situation in bean seeds which is similar to secondary dormancy.

As with dormant seeds, C6/C1 ratios of embryonic axes of seeds soaked in air-saturated water remained high (0.8–1.0) during and after soaking. This was paralleled by low activities of glucose-6-phosphate dehydrogenase (EC.1.1.49) and 6-phosphogluconate dehydrogenase (EC 1.1.1.44). In axes of seeds soaked in CO2-saturated water and in unsoaked seeds C6/C1 ratios declined steadily during soaking/imbibition and reached values of around 0.3 after germination. Slight increases ofglucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities occurred in the pre-germination phase. This was followed by a massive increase after radicle emergence. Synthesis of the plastid isoenzymes was a post-germinative event.

It appears that soaking injury depresses protein synthesis. Lack of oxidative pentose phosphate pathway activity appears to be a causative factor in soaking injury.

Seeds that store proteins in protein storage vacuoles are attractive bioreactors for producing and storing large amounts of pharmaceutical proteins. However, foreign proteins expressed in transgenic plants are subjected to the delivery and modification processes present within plant cells. Here, it is demonstrated that unique membrane sequences deliver a yellow fluorescent protein (YFP) to the seed protein storage vacuoles in transgenic tobacco (Nicotiana tabacum L.) plants, where the YFP is then separated from its membrane anchors. This precise targeting and separation is required for the successful delivery of useful proteins to seed protein storage vacuoles for their stable accumulation in transgenic crops.

Endosperm tissue that nourishes the embryo during seed development, upon maturity, nourishes the global population with special reference to cereal crops like maize, wheat and rice. In about 70% of the angiosperms, endosperm genome content is ‘3n’ with 2:1 (maternal:paternal) contribution, as a result of the second fertilization event. However, angiosperms evolution also documents diversity in endosperm genome content from ‘2n’ to ‘15n’, in scale with the corresponding maternal genome dosage variability (‘1n’ to ‘14n’), whereas paternal contribution is invariable. In apomicts, due to lack of fertilization, or pseudogamy (fertilization of the central cell for endosperm formation), endosperm genome dosage (m:p) has been reported to range between 1:1 and 8:3. Exceptionally, the central cell with one unreduced nucleus and fused with a reduced sperm cell, with 2:1 normal genome dosage, has been reported in Panicum. Altered genome dosage levels are reportedly correlative with eccentricities among maternal and paternal contribution to seed resource allocation. Besides endosperm ploidy variability between species of angiosperms, the present review gives an overview of the ploidy variability in endosperm cells within a seed, up to ‘690n’. In addition to genome-scale variability in the endosperm, some taxa of angiosperms exhibit chlorophyllous endosperms and some chlorophyllous embryos. Also, endosperm cell number during seed development is reported to have a strong association with grain weight at maturity. Genes underlying these traits of variability are unknown, and the present review underscores the variability and highlights the potential of the single-cell sequencing techniques towards understanding the genetic mechanisms associated with these variable traits.

There is a worldwide consensus that the production of food, biomolecules and bioenergy should be sustainably intensified within the next decades. To achieve these goals will depend on the intensification of current practices in agricultural systems fused with a wider understanding and acceptance of genomics, metabolomics, synthetic biology and metabolic engineering. However, genetically modified-derived crops, including commodities and non-commodities, may contribute to establishing a new parameter in the agricultural, pharmaceutical and industrial sectors. Seeds will also play an important role in allowing large-scale production of innovative molecules prospected from biodiversity.

Mudflats are exposed for short periods after flood water drawdown. They support fast-growing annual herbs with a ruderal strategy. To optimize their recruitment success, seeds of mudflat species germinate better under fluctuating temperatures, full illumination and aerobic environments that indicate the presence of optimal (non-flooded) conditions for plant growth and development. Here, we hypothesize that prior exposure of mudflat seeds to hypoxic (flooded) environment interferes with the germination process and results in more vigorous germination once aerobic conditions are regained. To test this hypothesis, seeds of five mudflat species were incubated in both aerobic and hypoxic environments at four (14/6, 22/14, 22/22 and 30/22°C) temperature regimes, reflecting different (seasonal) conditions when drawdowns may occur. All species responded positively to four temperature regimes; however, moderate 22/14 and 22/22°C temperatures were optimum for high percentages and rates (speed) of seed germination. Since seeds of four species germinated exclusively under aerobic conditions, they were moved from hypoxic to aerobic conditions. Prior exposure of seeds to hypoxic environment facilitated high percentages, rates and synchronization of germination of Limosella aquatica, Peplis portula and Samolus valerandi seeds compared to incubation under strict aerobic conditions. However, prior exposure to hypoxic environment induced secondary dormancy in non-dormant seeds of Hypericum humifusum but broke dormancy in Lythrum hyssopifolia seeds that otherwise required cold stratification to overcome physiological dormancy. All species that have a narrow ecological niche (strictly occurring in mudflat habitats) showed positive responses to prior exposure to hypoxic environments. In contrast, H. humifusum that has a wide ecological niche (from mudflats to moist sandy grasslands) showed a negative response. We conclude that the hypoxic environment may strongly affect seed germination behaviour once the aerobic environment is regained. The most striking effect is the acceleration of the germination process and, therefore, life cycle supporting the survival in an ephemeral habitat.

The three tropical species Gomphandra luzoniensis, Nothapodytes nimmoniana and Goniothalamus amuyon contain important cancer-fighting drugs; however, little is known about how to propagate these species from seeds. Thus, the aim of this study was to determine the germination requirements of seeds of each of these three species in order to provide an effective protocol to produce plants. Fresh seeds of G. luzoniensis germinated up to 73% at high temperatures in light in 4 weeks, and embryos were underdeveloped. Most seeds had morphological dormancy (MD), but a proportion of them had morphophysiological dormancy (MPD). Fresh seeds of N. nimmoniana germinated up to 50% in light in 4 weeks, embryo length increased by 17% before radicle emergence and ≥ 89% of the seeds had germinated after incubation for 6 weeks in light at high temperatures. Thus, about 50% of the seeds have MD and about 50% MPD. Fresh seeds of G. amuyon incubated at 30°C in light for 4 weeks germinated to 69%, whereas at the other incubation temperatures germination took longer than 4 weeks. Embryo length increased 213% before radicle emergence, and after 8 weeks of incubation at high temperatures ≥ 80% of the seeds had germinated. As in the other two species, the seed population consisted of a mixture of MD and MPD. Incubation of seeds of these three species at high temperatures (e.g. 25, 30 and 30/20°C) for up to 2 months is recommended for germination and thus seedling production.

Group testing is a procedure in which groups that contain several units (plants) are analysed without having to inspect individual plants, with the purpose of estimating the prevalence of genetically modified plants (adventitious presence of unwanted transgenic plants, AP) in a population at a low cost, without losing precision. When pool (group) testing is used to estimate the proportion of AP (p), there are several procedures that can be used for computing the confidence interval (CI); however, they usually do not ensure precision in the estimation of p. This research proposes a formula for determining the required number of pools (g), given a pool size (k), for estimating the proportion of AP plants using the Dorfman model. The proposed formula ensures precision in the estimated proportion of AP because it guarantees that the width (W) of the CI will be equal to, or narrower than, the desired width (ω), with a probability of γ. This probability accounts for the stochastic nature of the sample variance of p. We give examples to show how to use the proposed sample-size formula. Simulated data were created and tables are presented showing the different scenarios that a researcher may encounter. The Monte Carlo method was used to study the coverage and the level of assurance achieved by the proposed sample sizes. An R program that reproduces the results in the tables and makes it easy for the researcher to create other scenarios is given in the Appendix.

Molecular mobility is hypothesised to be a key factor influencing storage stability of seeds because it may control the rate of deteriorative reactions responsible for reduced shelf life. The relationship between the longevity of lettuce seeds and the molecular mobility was investigated in the cytoplasm of lettuce radicles. Longevity of lettuce seeds was predicted using the viability equation of Ellis and Roberts, and the molecular mobility was determined by saturation transfer electron paramagnetic resonance spectroscopy measurements of rotational motion of a polar spin probe inserted into the cytoplasm. Increasing the temperature resulted in faster rotational motion and shorter longevity. There was a linear relationship between the logarithms of rotational motion and estimated seed longevity for temperatures above 5°C. Below 5°C, there was a deviation from linearity. Based on the hypothesis that the molecular mobility in the cytoplasm determines the rate of detrimental reactions, seed longevity at sub-zero temperatures was predicted by extrapolation of the rotational motion using the linear relationship. Predictions of longevity at sub-zero temperatures based on rotational motion indicated longer survival times than those based on the viability equation. A kinetic approach to ageing using molecular mobility measurements is expected to improve our understanding of seed storage stability and might eventually lead to realistic predictions of longevity at low temperatures.

This paper examines the dispersal–germination strategy of seeds of 66 native tree species from a seasonal evergreen monsoon rainforest on Hainan Island, China, and assesses correlations among seed germination and phylogeny, dispersal mode and dispersal season. Seeds of 15, 7, 25 and 19 species were dispersed during the warm dry (March–May), rainy (June–September), late rainy (October–November) and cool dry (December–February) seasons, respectively. Berries (16 species), drupes (14 species) and capsules (12 species) were common and represented about 64% of the species. Zoochory was the most common dispersal mode (69.7%) followed by anemochory (16.7%) and autochory (13.6%). More than 65% of species had dormant seeds. Based on germination speed and synchrony, six patterns were recognized: rapid and synchronous germination (13 species), intermediate and synchronous germination (3 species), intermediate and intermediately synchronous germination (24 species), intermediate and asynchronous germination (2 species), slow and intermediately synchronous germination (5 species), and slow and asynchronous germination (19 species). One-way ANOVAs revealed that the variance in germination percentages among species was largely dependent upon phylogeny. The mean and median length of germination (MLG) were largely dependent upon phylogeny, dispersal mode and dispersal season. Anemochorous seeds germinated faster than autochorous and zoochorous seeds. Seeds dispersed in the late dry or early rainy season (March–May) tended to germinate quickly, whereas those dispersed towards the end of the rainy season and into the cool dry season are likely to have a much longer length of dormancy. Correlation analyses indicated that larger seeds germinated faster and had higher germination percentages.

Raphanus raphanistrum (wild radish) is a highly competitive weed in winter crops. Integrated weed management practices and decision-making tools benefit from the ability to predict seed longevity and dormancy status in the soil seed bank, as well as time and density of emergence in the field. We wondered if unique values taken from databases could serve for modelling purposes, whatever the origins of the weed populations. We investigated dormancy and longevity of fruits buried in the soil over a four-year seed burial experiment of two highly contrasted populations that differ by their biogeographical origin (oceanic versus continental climate), their habitat (arable field versus undisturbed) and their fruit size (thick versus thin fruit wall). High viability persisted over two years, followed by a rapid reduction, especially for the ‘continental-undisturbed-thin’ population. Dormancy cycling, with dormancy at its lowest in October, was observed for the ‘oceanic-arable-thick’ population, whilst a slow decrease without clear seasonal pattern was found for the other population. These results indicate different ways of regulating seed persistence in the soil, which might be taken into account when building demographic models. These differences could be due to interactions between fruit wall thickness and the other factors; it is possible that a thicker fruit wall increases longevity by promoting dormancy by physical restriction, but depending on temperature. Thinner fruit walls would make plants display other adaptive strategies to maximize survival time in the soil seed bank. Studies involving more populations and isogenic material are needed to address this specific question.