Seed Science Research最新文献

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.

Seed dormancy in plants can have a significant impact on their ecology. Recent work by Rojas-Villa and Quijano-Abril (2023) classified the seed dormancy class in 14 plant species from the Andean forests of Colombia by using germination trials and several microscopy techniques to describe seed anatomy and morphology. The authors conclude that Cecropia species have both physical and physiological dormancy (of which they call physiophysical dormancy) based on seed morphology and mean germination times of over 30 days. Here, we present seed permeability and germination data from neotropical pioneer tree species: Ochroma pyramidale, Cecropia longipes, and Cecropia insignis, as well as Cecropia peltata (present in Rojas-Villa and Quijano-Abril, 2023), to demonstrate that Cecropia species do not exhibit dormancy and also have high levels of seed permeability. We find that the mean germination time for all three Cecropia species in our study was less than 30 days. This suggests a need for reporting the conditions in which germination trials take place to allow for comparability among studies and using seed permeability tests to accurately identify the physical dormancy class of seeds. Further, we present data from the literature that suggests that dormancy is not a requirement for seed persistence in the seed bank.

Seed germination is a pivotal period of plant growth and development. This process can be divided into four major stages, swelling absorption, seed coat dehiscence, radicle emergence and radicle elongation. Cupressus gigantea, a tree native to Tibet, China, is characterized by its resistance to stresses such as cold, and drought, and has a high economic and ecological value. Nevertheless, given its unique geographic location, its seeds are difficult to germinate. Therefore, it is crucial to explore the mechanisms involved in seed germination in this species to improve the germination efficiency of its seeds, thereby protecting this high-quality resource. Here, our findings indicate that seed germination was enhanced when exposed to a 6-h/8-h light/dark photoperiod, coupled with a temperature of 20°C. Furthermore, the application of exogenous GA3 (1 mg/ml, about 2.9 mM) stimulated the germination of C. gigantea seeds. Subsequently, proteomics was used to detect changes in protein expression during the four stages of seed germination. We identified 34 differentially expressed proteins (DEPs), including 13 at the radicle pre-emergence stage, and 17 at the radicle elongation stage. These DEPs were classified into eight functional groups, cytoskeletal proteins, energy metabolism, membrane transport, stress response, molecular chaperones, amino acid metabolism, antioxidant system and ABA signalling pathway. Most of them were found to be closely associated with amino acid metabolism. Combined, these findings indicate that, along with temperature and light, exogenous GA3 can increase the germination efficiency of C. gigantea seeds. Our study also offers insights into the changes in protein expression patterns in C. gigantea seeds during germination.

Seed dormancy is an important trait associated with pre-sprouting and malting quality in barley. Genome-wide association studies (GWASs) have been used to detect quantitative trait loci (QTLs) underlying complex traits in major crops. In the present study, we collected 295 barley (Hordeum vulgare L.) accessions from Australia, Europe, Canada and China. A total of 25,179 single nucleotide polymorphism (SNP)/diversity arrays technology sequence markers were used for population structure, linkage disequilibrium and GWAS analysis. Candidate genes within QTL regions were investigated, and their expression levels were analysed using RNAseq data. Five QTLs for seed dormancy were identified. One QTL was mapped on chromosome 1H, and one QTL was mapped on chromosome 4H, while three QTLs were located on chromosome 5H. This is the first report of a QTL on the short arm of chromosome 5H in barley. Molecular markers linked to the QTL can be used for marker-assisted selection in barley breeding programmes.

Time-separated seed collections with a separation period of 12–18 years were used to study recent changes in germination traits and the role of climate factors in seven tropical dry forest (TDF) woody species in Zambia, southern Africa. In all the species, peak and final germination were lower in recent (2016–2021) seed collections than in historic (1998–2005) seed collections during the first germination season. However, in species with seed dormancy, both peak and final germination after one year burial were higher in recent seed collections than in historic seed collections. Three monthly climate factors had significant effects on final germination in the different species and the timing of most of these factors was during seed development and ripening that suggest that these factors operated through mother plants. In species with seed dormancy, post-first-year germination of buried seeds responded to climate factors in the regeneration niche. Climate factors that significantly affected germination included those that changed over the separation period between historic and recent seed collections. This indicates that short-time climatic changes may have the potential to impact germination in TDF woody species of southern Africa. The germination responses to climate factors were both positive and negative and it is not clear whether these are adaptations or not. Further research is required to assess the adaptive significance of these changes in germination traits in TDF species of southern Africa.

Alpine plant species are particularly vulnerable to climate change. Temperature fluctuations are projected to be most severe at high elevations. Even small shifts in temperature have major consequences on phenology, reproduction, and community composition. Early life stages are arguably the most important processes in the fitness of an individual plant and the dynamics and persistence of plant populations. These initial developmental stages are expected to be more vulnerable to changes in climate than adult life stages. To understand how early life stages of alpine plant species will respond to warming temperatures, seeds and seedlings of two species were exposed to three different temperature regimes. Temperatures were based on current and projected conditions under low and high emission scenarios. Two rare alpine species performed better under warmer temperatures at both the germination and seedling stages. The results show that early life stages of alpine plants may not be at high risk from warming temperatures; however, there are many other shifting climatic factors to consider, resulting from climate change beyond temperature alone.

This work provides insights into the deterioration of cacti seeds of Escontria chiotilla (F.A.C. Weber ex K. Schum) and Stenocereus pruinosus (Otto ex Pfeiff.) Buxbaum stored ex situ at 25 °C, under dry and dark conditions or buried in situ conditions in a xerophytic shrubland. Viability, germination speed, electrolyte leakage and indicators of the redox balance including glutathione content, glutathione half-cell reduction potential (EGSSG/2GSH) and malondialdehyde (MDA), oxidized protein content, together with water-soluble antioxidant enzyme activity were assessed. Over a period of two years of storage, viability was maintained when seeds were stored ex situ at 7–9% water content compared to seeds buried in the soil. A second burial experiment showed that seeds of E. chiotilla maintained viability during a year of storage that included a rainy season followed by a dry season. Thereafter, they died rapidly during the second rainy season. In contrast, those of S. pruinosus started to lose viability after 6 months of burial at the end of the rainy season and were mostly dead at the end of the dry season. This difference in persistence between species was related to a difference in the glutathione content and antioxidant enzyme activities. In both storage experiments, the loss of viability of both species was associated to a EGSSG/2GSH shift to a more oxidative state during burial. Yet, contents in MDA and oxidized soluble proteins were not related to redox imbalance and loss of viability, indicating that these compounds are not good markers of oxidative stress in cacti seeds during storage.

The assessment of seed quality and physiological potential is essential in seed production and crop breeding. In the process of rapid detection of seed viability using tetrazolium (TZ) staining, it is necessary to spend a lot of labour and material resources to explore the pretreatment and staining methods of hard and solid seeds with physical barriers. This study explores the TZ staining methods of six hard seeds (Tilia miqueliana, Tilia henryana, Sassafras tzumu, Prunus subhirtella, Prunus sibirica, and Juglans mandshurica) and summarizes the TZ staining conditions required for hard seeds by combining the difference in fat content between seeds and the kinship between species, thus providing a rapid viability test method for the protection of germplasm resources of endangered plants and the optimization of seed bank construction. The TZ staining of six species of hard seeds requires a staining temperature above 35 °C and a TZ solution concentration higher than 1%. Endospermic seeds require shorter staining times than exalbuminous seeds. The higher the fat content of the seeds, the lower the required incubation temperature and TZ concentration for staining, and the longer the staining time. And the closer the relationship between the two species, the more similar their staining conditions become. The TZ staining method of similar species can be predicted according to the genetic distance between the phylogenetic trees, and the viability of new species can be detected quickly.