This study investigates how methodological aspects of seed-bank sampling affect seed-bank records in temperate deciduous forests. We focused explicitly on seed-bank records of ancient forest species, which are assumed to lack a persistent seed bank; a hypothesis suspected to be partly due to methodological shortcomings. Through a quantitative review of 31 seed-bank studies in temperate deciduous forests of central and north-west Europe, we quantified the role of sampling methodology in constraining total seed-bank records and seed-bank records of ancient forest species (γ-diversity, average species' retrieval frequency and average seed density). A major methodological trade-off was established between sampled plot area and the number of plots: at an increased number of plots, the area sampled per plot decreased significantly. The total surface area sampled in a study was the primary determinant of γ-diversity, both for overall species richness and for ancient forest species richness. A high retrieval frequency of ancient forest species indicated that few plots were intensively sampled. The parallel increase in total species richness and ancient forest species richness and the non-significance of their ratio in relation to methodological variables suggests that ancient forest species are not particularly rare in the seed bank compared to other species. These results imply that sampling methodology has a far-reaching impact on seed-bank records such as γ-diversity, the detection of ancient forest species and ultimately seed-bank composition. We formulate a set of guidelines to improve the quality of seed-bank studies in temperate deciduous forests.

The most common way to test seed quality is to use a simple and reliable but time- and space-consuming germination test. In this paper we present a fast and simple method to analyse cabbage seed deterioration by measuring ethanol production from partially imbibed seeds. The method uses a modified breath analyser and is simple compared to gas chromatographic or enzymatic procedures. A modified method using elevated temperatures (40°C instead of 20°C) shortened the assay time and improved its sensitivity. The analysis showed an inverse correlation between ethanol production and seed quality (e.g. the final percentages or speed of germination and the number of normal seedlings). The increase in ethanol production was observed when cabbage seeds were deteriorated by storage under ambient conditions or hot water treatments, both of which reduced the number of normal seedlings. Premature seeds produced more ethanol upon imbibition than mature seeds. Ethanol production occurred simultaneously with oxygen consumption, indicating that lack of oxygen is not the major trigger for ethanol production.

Temperature has a key influence over seed dormancy and germination, allowing wild plants to synchronize their life history with the seasons. In this review we discuss the signalling pathways through which temperature is integrated into seed physiology and the control of primary and secondary dormancy, with an emphasis on understanding maternal effects and responses dictated by the zygotic tissues. A key emerging paradigm is that temperature signalling in seeds must be understood in relation to whole plant genetics and physiology, as overlapping pleiotropic roles for temperature sensing and hormone signalling pathways are commonplace.

Temperature is a key environmental signal regulating germination. A thorough understanding of how seed populations respond to various temperatures can inform end-users regarding effective establishment strategies and forms the basis for questions related to a taxon's thermo-biology. Although abundant information exists regarding germination responses of economically important crops to several temperature scenarios, much less is known concerning the seed biology of wild germplasm. To address this, we examined the germination response of non-dormant Rudbeckia mollis seeds to various doses of constant or simulated seasonal diel temperatures. Germination response was sigmoidal. Seeds of R. mollis were capable of germinating within a few days to high percentages (>95%) at relatively cool constant (15–25°C) or 12-hour alternating (22/11–33/24°C) temperatures, with optimum temperatures for germination occurring at 25°C or 29/19°C. Germination was inhibited as temperatures increased to 30°C or 33/24°C with early and late germinating phenotypes displaying differential responses at these temperatures. No germination occurred at 35°C. Results are discussed in terms of seedling establishment of R. mollis outside its natural range and implications of climate change on germination.

The purpose of the present study was to investigate the dormancy break and germination requirements of seeds from the rhamnaceous vine Berchemia scandens. The fleshy fruit contains a two-locular stone with an endocarp described as ‘bony, thickish’. Scarified and non-scarified stones increased by about 30–50% in mass during imbibition over a 24-h period. The endocarp of the stone does not completely enclose the seeds and a soft tissue region is present. This region is the primary area of water entrance to the seed, as shown by dye-tracking and by sealing it. Freshly matured and overwintered seeds of B. scandens germinated to low percentages at all temperatures during 2 weeks of incubation in light, and they germinated from moderate to high percentages during 12–14 weeks of incubation in light. While cold stratification had a relatively modest effect on the promotion of total germination across most temperatures assessed (if seeds were left for long enough), it had a somewhat stronger effect on germination rate. Cold-stratified seeds germinated equally well in light and darkness. The class of dormancy found in seeds of B. scandens would be physiological. The anatomy of the stones readily allows water imbibition, showing that seeds of B. scandens lack physical dormancy, an uncommon trait in Rhamnaceae.

Seven ancient seeds, about 1600 years old, were found during an archaeological excavation in Asar Island which is located in south-western Turkey. These seeds were subjected to germination, in vitro callus induction and molecular characterization experiments to test the viability and plant origin of the seeds. Six of the seven seeds had viable seed components (such as cotyledons) and produced callus tissue in Murashige and Skoog medium supplemented with 2 mg l− 1 6-benzylamino purine (BAP), 0.2 mg l− 1 1-naphthaleneacetic acid (NAA), 20 g l− 1 sucrose, 2 mg l− 1 glycine and 7 g l− 1 agar, but the calli from these seeds failed to yield adventitious shoots. DNA samples from callus tissues produced by ancient seeds in vitro were of good quality. The internal transcribed spacer (ITS) region in nuclear DNA (nDNA) of ancient seeds was amplified successfully. The sequences from amplified ITS DNA products of six ancient seeds indicated that their ITS sequences matched those of Anagyris foetida after subjecting them to BLAST searches in international sequence databases (NCBI). A. foetida is a relict species endemic to the Mediterranean region and used as a herbal medicine. We believe that seed characteristics such as the very hard, extremely smooth and shiny testa, toxic anagyrine alkaloid content and their storage in a pot further improved the longevity of these ancient seeds.

Thioredoxins (Trxs) are widely distributed, small proteins that function in redox regulation in a broad spectrum of cellular reactions. Experimental work with barley, wheat and a legume (Medicago truncatula) has established thioredoxin h (Trx h) as a central regulatory protein in seeds, reducing disulphide (S–S) groups of diverse seed proteins, including storage proteins, enzymes and enzyme inhibitors. Trxs appear to be particularly important in plants, as a large number of genes are present compared to mammalian organisms. In Arabidopsis thaliana there are approximately 20 different genes for classical Trxs, and large Trx gene families have also been found in cereals, such as rice, barley, wheat and sorghum. Extensive evidence indicates that adding Trx, reduced nicotinamide adenine dinucleotide phosphate (NADPH) and NADP-thioredoxin reductase (NTR) to cereal flour or seed preparations reduces disulphide (S–S) linkages of storage proteins. The early in vitro studies have been complemented with transgenic barley seed, overexpressing Trx h in protein bodies of the barley endosperm, which showed accelerated germination and early or enhanced expression of associated enzymes, i.e., α-amylase and pullulanase. Overexpression of Trx h levels in wheat was subsequently shown to (1) enhance protein solubility and digestibility, (2) reduce allergenicity of wheat gliadins, and (3) improve dough quality from poor-quality wheat flour. Most recently, we have demonstrated that down-regulation in wheat of Trx h9, a unique thioredoxin, leads to a reduction in the incidence of pre-harvest sprouting, demonstrated in several varieties over multiple generations with field-grown material. Yield and starch content were increased while baking quality in the high-gluten variety remained unchanged. These observations led to the intriguing question of how changes in the endosperm are communicated to the embryo. Studies of Trx h9, a membrane-associated Trx h that can move from cell to cell, provide suggestive evidence for a role of Trx h9 in intercellular communication of redox state.

To improve understanding of how a rare endemic species of Centaurium adapts to a specialized ecological niche, we studied the germination ecology of the mountain spring specialist, C. somedanum, a perennial species restricted to an unusual habitat for this genus. We conducted laboratory experiments with fresh seeds collected from two populations for three consecutive years, to investigate: (1) the effect of temperature and light on germination; (2) the existence of seed dormancy; and (3) inter-population and inter-annual variation in germinability. Germination occurred only in the light and at relatively low temperatures (15–22°C) with no differences between constant and alternating regimes, and a significant decrease at high temperatures (25°C and 30°C). We found non-deep simple morphophysiological dormancy and variation in seed germinability depending on the year of seed collection. C. somedanum diverged from the common germination characteristics of the genus in: (1) its germination at lower temperatures, which contrasts with what is generally expected in wetland species but could be adaptive in the spring habitat; and (2) its morphophysiological dormancy, which we report here for the first time in the genus and which could be an adaptation to its mountain habitat.

The naturally occurring fungal seed pathogen, Pyrenophora semeniperda, reduces the seed bank of Bromus tectorum but the role of plant litter in this seed–pathogen interaction is unexplored. To investigate the direct and indirect effects of litter on this interaction, we first collected field seed-bank samples from low and high Bromus litter patches. From these data, we explored the relationship between litter depth, seed-bank density and seed mortality from P. semeniperda. Second, we manipulated the fungal stages (conidial spores and mycelium) in/on the litter through sterilization techniques, to measure the direct effect of litter on seed death. Third, for indirect effects, we manipulated litter levels and held seed density and inoculum constant to determine whether Bromus litter could modify the seed zone microsites to favour disease. We found that seed-bank samples from high-litter patches contained higher field-killed seed densities compared with low-litter patches, although the percent difference of disease between litter patch types varied among sites and years (e.g. 80% to 46%). In testing the direct effects of litter on the seed–pathogen interaction, we found that litter can act as a direct inoculum source for the pathogen in the early summer but decreases in disease transmission by the following spring when the litter naturally is in contact with seeds. Investigating indirect effects, we found four times as many pathogen-killed seeds in high-litter treatments as compared with low-litter treatments when inoculum loads and seed densities were held constant. In addition, we found that litter influences the seed–pathogen interaction through density-dependent disease transmission. Our findings demonstrate the ecological importance of litter in semi-arid environments as it influences disease levels of a seed pathogen by direct and indirect means.

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.

Soil seed banks are important to vegetation recruitment, ecosystem functioning and land management. We evaluated composition of 0–5 cm soil seed banks and relationships of seed banks with forest community types (ranging from low-elevation pinyon–juniper to high-elevation bristlecone pine), vegetation cover and environmental variables within a 40,000-ha relatively undisturbed coniferous forest landscape in Nevada, USA. We collected samples from 36 sites and used the emergence method to assay seed banks. Seed density averaged 479 seeds m− 2 across sites and a total of 39 taxa were detected. Most (79%) of these taxa were perennials and 35 of 39 (90%) were native. Moreover, 62% of seed-bank taxa were in the vegetation of mature forests, an uncommon finding in studies of forest soil seed banks. Seed-bank density, species richness and composition did not display strong relationships with forest community types, vegetation cover or environmental variables. Weak relationships likely arose from the relatively uniform seed-bank density among sites, where 50% of sites had seed densities in the range of 106–282 m− 2. Results suggest that while seed banks on this landscape are not large, they provide recruitment potential for some native perennial species of mature, relatively undisturbed communities.

Seed germination is a crucial event in a plant's life cycle. Because temperature and water availability are important regulators of seed germination, this process will likely be influenced by global warming. Insight into the germination process under global warming is thus crucial, and requires the study of a wide range of water availability and temperature conditions. As hydrothermal time (HTT) models evaluate seed germination for any combination of water potential and temperature, they can be suitable to predict global warming effects on seed germination. We studied the germination characteristics of the high Andean endemic tree species Polylepis besseri (Rosaceae), using HTT models. We were especially interested in the potential effects of global warming on seed germination. Assembly of HTT models for P. besseri was fairly straightforward due to the lack of a seed dormancy mechanism. The models allowed prediction of Polylepis germination under constant and alternating temperatures. Initially, a global warming induced increase in the field minimum and mean temperature will increase P. besseri germination, but as maximum temperatures rise above the optimum temperature for the species, seed germination will become jeopardized. Effects of global warming on seed germination are currently considerably underexplored. HTT models prove to be useful tools to study a plant species' general germination characteristics, and how they may become affected under global warming. For the endemic mountain tree species P. besseri, we predict an increase, followed by a decrease of seed germination under global warming.

The seasonality of the Mediterranean climate has important implications for plant physiology and some specific conditions must be met before germination can occur. Most plants sprout during the spring season although a few germinate during the autumnal rainy period. To understand the patterns of germination under autumn conditions we selected five Mediterranean autumn-flowering geophytes that usually co-exist in fire-prone habitats: Leucojum autumnale, Narcissus cavanillesii, Narcissus serotinus, Scilla autumnalis and Urginea maritima. Experiments were performed under conditions simulating those prevailing in the habitat during the autumnal Mediterranean season when seeds of these species usually germinate. In all species, germination occurred quickly ( < 7 d), was usually higher at the lowest temperatures tested (15°C, 20°C; >89%) and no signs of delayed germination were detected. Nevertheless, species usually had different patterns of seed germination, a strategy that might avoid interspecific competition when co-occurring in the same habitats. Germination was lower and slower in light than in darkness, suggesting that under natural conditions germination of seeds directly exposed to sunlight can be severely restricted. Several fire-dependent treatments (heat and ash) revealed a lack of fire-stimulated germination, and treatments even had a negative effect. In addition, only a small fraction of seeds remained viable after 1 year of dry lab storage and their germinability was very low, suggesting the absence of a permanent soil seed bank in the life cycle of these geophyes.

Seed quality is a complex trait that is the result of a large variety of developmental processes. The molecular-genetic dissection of these seed processes and their relationship with seed and seedling phenotypes will allow the identification of the regulatory genes and signalling pathways involved and, thus, provide the means to predict and enhance seed quality. Natural variation for seed-quality aspects found in recombinant inbred line (RIL) populations is a great resource to help unravel the complex networks involved in the acquisition of seed quality. Besides extensive phenotyping, RILs can also be profiled by -omics technologies, such as transcriptomics, proteomics and metabolomics in a sophisticated so-called generalized genetical genomics approach. This combined use of physiology, genetics and several -omics technologies, followed by advanced data analysis, allows the construction of regulatory networks involved in the various attributes of seed and seedling quality. This type of analysis of the genetic variation in RIL populations in combination with genome-wide association (GWA) studies will allow a relatively rapid identification of genes that are responsible for quality-related traits of seeds and seedlings. New developments in several -omics technologies, especially the fast-evolving next-generation sequencing techniques, will make a similar system-wide approach more applicable to non-model species in the near future and this will be a huge boost for the potential to breed for seed quality.