Seed Science Research最新文献

Although seed trait variations and their relationship to the ecological niche have been studied extensively at the species level, they do not necessarily reflect variations at the population level. In this study, we explored the intra-specific variation in relative embryo length, seed mass and germination speed in 40 populations of Daucus carota distributed across Europe and North America. By including information on local climate conditions, we aimed to examine the impact of the geographical origin on various seed functional traits and to detect potential local adaptation. No significant difference was observed in final seed germination for European and North American seeds incubated at 20°C, nor in seed viability. In European populations, relative embryo length significantly increased with increasing seed mass, but no such relation was found in North American populations. Larger relative embryo length at dispersal resulted in increased germination speed in both European and North American populations. Populations in drier areas typically had seeds with larger relative embryo lengths. Precipitation-related climate variables showed a negative relationship with relative embryo length, indicating a reduction in relative embryo length with increased precipitation. No clear relationship between climate and seed mass was observed. We can conclude that seed functional traits of D. carota are adapted to local climate conditions, as a clear gradient was observed in the relative embryo length of D. carota, which was associated with germination speed and climate. This gradient was less pronounced in North America, which can be explained by its relatively recent introduction to the continent.

Nypa fruticans Wurmb is both a relic plant and a true mangrove. In China, wild populations are distributed only on Hainan Island and face significant challenges in regeneration from seedlings. This study explored the underlying causes of recruitment limitation by examining seed morphological traits from three distinct populations (Haikou, Wenchang and Wanning) and analysing seed germination and seedling growth characteristics under varying conditions. The key findings are as follows: fruiting and seed-setting rates for N. fruticans were notably low, standing at only 21 and 40%, respectively. The Wanning population exhibited significantly higher rates compared to the other two populations. Under natural conditions, the germination and seedling emergence rates were also modest, at 36.58 and 22.99%, respectively. The germination and emergence rates of the Wanning population were significantly greater than those of the Haikou and Wenchang populations. Meanwhile, seeds from a single population did not differ in germination rates among three in situ N. fruticans habitats, but seedling emergence rates differed significantly. Optimal conditions for seed germination involved a light intensity of 60%, a salinity of 5‰ and a flooding time of 8 h/day. In natural settings, these three environmental factors fall short of the ideal conditions. The study underscores that light, salinity and flooding are primary factors contributing to the limitations in N. fruticans seedling recruitment. In addition to advocating increased investment in scientific research and technology to address seed source issues, we recommend heightened efforts in habitat restoration, in situ conservation and the optimization of relocation and field return strategies to bolster N. fruticans populations.

The performance of plants in any one generation can be influenced not just by the prevailing biotic and abiotic factors, but also by those factors experienced by the parental generation. These maternal effects have been recorded in an array of plant species, but most studies tend to focus on abiotic factors over two generations. Here we show that maternal effects in the annual forb Senecio vulgaris may be influenced by beneficial arbuscular mycorrhizal fungi and insect herbivory over four successive generations. These effects were very much determined by seed provisioning, wherein C:N:P ratios were altered by both fungi and aphids. There was little evidence of epigenetic changes induced by the fungi or insects, instead the driving forces seemed to be allocation of N and P to the seeds. However, changes in seed chemistry were not cumulative over generations, often decreases in seed nutrient content were followed by recovery in subsequent generations. The changes in seed stoichiometry can have important consequences for viability, germination and subsequent seedling growth rates. We conclude that studies of maternal effects need to be conducted over multiple generations, and also need to be multifactorial, involving variation in abiotic factors such as water and nutrients, combined with biotic factors.

Seed genebanks must maintain collections of healthy seeds and regenerate accessions before seed viability declines. Seed shelf life is often characterized at the species level; however, large, unexplained variation among genetic lines within a species can and does occur. This variation contributes to unreliable predictions of seed quality decline with storage time. To assess variation of seed longevity and aid in timing regeneration, ten varieties of pea (Pisum sativum L.), chickpea (Cicer arietinum L.) and lentil (Lens culinaris Medikus subsp. culinaris) from the Australian Grains Genebank were stored at moderate temperature (20°C) and moisture (7–11% water, relative humidity [RH] ~30%) and deterioration was assessed by yearly germination tests for 20 years. Decline in germination was fit to a sigmoidal model and the time corresponding to 50% germination (P50) was used to express seed longevity for each genetic line. The feasibility of using RNA fragmentation to assess changed seed health was measured using RNA integrity number (RIN) from RNA extracted from seeds that were stored for 13 and 20 years. Seed lots of legume grains that maintained high survival throughout the 20 years (i.e. they aged slower than other lines) had higher RIN than samples that degraded faster. RIN was lower in embryonic axes compared with cotyledons in the more deteriorated samples, perhaps indicating that axes exhibit symptoms of ageing sooner than cotyledons. Overall, RIN appears to be associated with longevity indicators of germination for these legumes and indicating that RIN decline can be used to assess ageing rate, which is needed to optimize viability monitoring.

Seeds of many Amazonian floodplain forest trees are dispersed during high-water periods and spend weeks or months underwater until the flooding retreats. To assess whether prolonged seed submersion affects germination and early seedling development, an experiment was carried out in a greenhouse with seeds of Campsiandra laurifolia, Cassia leiandra, Crataeva tapia, Ilex inundata, Macrolobium acaciifolium, Nectandra amazonum, Pouteria glomerata, Psidium acutangulum, Sorocea duckei, and Vitex cymosa. They are common in this type of forest, differ in fruit type, number of seeds per fruit, fruit dimensions, and fresh mass and have fruits or seeds that can float. Seeds were collected in a Central Amazonian floodplain forest (flooded approximately 6 months year−1; water column of 5 m) and germinated in (1) irrigated soil or (2) underwater (water column of 5–7 cm) for 6 months. Seeds that germinated underwater were transferred to drained soil. Seeds of all species germinated underwater and developed seedlings when transferred to soil. However, submersion reduced the germination percentage of Psidium acutangulum, N. amazonum, P. glomerata and V. cymosa. Six species delayed germination in water. Ca. leiandra, I. inundata and P. glomerata did not differ in mean germination time in drained soil and underwater, whereas S. duckei seeds germinated faster underwater. Seed submersion negatively affected seedling growth (shoot length) of three species but did not affect seedling biomass. Timing of fruit dispersal, fruit buoyancy and high number of seeds per fruit can be critical for species with seeds that are not as able to cope with long-term submersion.

The environment experienced by a plant before and after reproduction can have a profound effect on the behaviour of the progeny after shedding. Maternal environmental effects on seeds are important for phenology and fitness in plants, especially for bet-hedging reproductive strategies. Maternal tissues that disperse with seeds are important for dormancy in many species, particularly those with coat-imposed dormancy and those that disperse in indehiscent fruits. Maternal nitrogen status, temperature and photoperiod modify maternal tissues and also influence the developing zygote. During seed development on the mother, the progeny may acquire environmental information directly, but there is also evidence for maternal–filial signalling and the epigenetic inheritance of environmental information through the germline.

Several experimental tools allow researchers to manipulate environmental variables to simulate future climate change scenarios during in situ seed ecology studies. The most common ones are designed to modify a single environmental variable. For example, open-top chambers (OTCs) increase temperature or rain-out shelters decrease precipitation. However, changes in environmental variables in the future are expected to happen simultaneously, and at present, an understanding of their combined effects in natural environments is limited. Here, we present a passive novel OTC design that simultaneously increases the soil temperature and decreases soil moisture. We assessed the performance of the design during 1 year in a high-mountain environment and reported its effects on the organic and topsoil layers. The modified OTC reduced the soil volumetric water content throughout the study period. Overall, chambers increased the mean day air temperature by 3.3 °C (at 10 cm above the soil surface), the mean day soil surface temperature by 1.35 °C and the mean day below the soil surface temperature by 1.30 °C (at −5 cm) and 1.25 °C (at −10 cm). Remarkably, surface and soil temperatures remained warmer at night (+0.65 at soil surface, +0.41 at −5 cm and +0.24 at −10 cm). We detail the design plans, tools and materials needed for its construction. Furthermore, we recommend on how to use it during seed ecology studies. This tool can help increase our understanding of the potential responses of seeds and seedlings to the combined effects of warming temperatures and a decrease in precipitation.

Grass seeds play a critical and fundamental role in grass breeding and production. Elymus sibiricus L. is a widespread Poaceae forage grass in northern Eurasia which is used for ecological restoration and forage production. Sucrose is the main source of substrate and energy required for starch synthesis in the seeds, so the hydrolysis of sucrose determines and influences starch synthesis and filling in the seeds, especially Poaceae. However, the process behind carbohydrate metabolism during E. sibiricus seed development remains unclear. This study addresses a significant gap in our understanding of the carbohydrate metabolism during seed development in E. sibiricus by employing full-length transcriptome sequencing across five developmental stages for the first time. Full-length transcriptome sequencing was performed on E. sibiricus seeds at five developmental stages (S5, S9, S15, S20, S25) to get better molecular insights. We identified 13,205 differentially expressed genes, with 7,471 up-regulated and 5,734 down-regulated. Through KEGG enrichment analysis, genes were enriched in ‘starch and sucrose metabolism’, ‘photosynthetic-related’ and ‘hormone signal transduction’ pathways. Gene ontology enrichment analysis showed that genes were enriched in the ‘beta-amylase activity’ term of molecular functions. In addition, top 21 transcription factor families were identified as involved in seed development. The homologous genes of ABSCISIC ACID-INSENSITIVE 3 (ABI3), NUCLEAR FACTOR-YB1 (NF-YB1), STARCH SYNTHASE I (SSI) were identified as candidate genes of seed development in E. sibiricus. Combined with physiological index, transcriptome analyses, weighted gene co-expression network analysis and real-time quantitative PCR, the mechanism of starch and sucrose content of seed development was revealed and ten hub genes were identified. Overall, this study provides the molecular bases to understand seed development and starch and sucrose metabolism at the different seed developmental stages in E. sibiricus.