Effects of Artificial Aging on Seed Vigor and Physiological Characteristics of the Invasive Alien Plant Aegilops tauschii

The control of invasive plants depends to some extent on the persistence of the soil seed bank. The high temperature (40 °C) accompanied with high humidity (95%) method was used to treat the seeds of the invasive species Aegilops tauschii Coss. The aim of our study was to evaluate the seed vigor and longevity by accelerating aging, to serve as a reference for the evaluation of invasion potential of A. tauschii and corresponding eradication strategy adoption. The results showed that with the extension of aging time, the germination rate (GR), energy (GE), and index (GI) of A. tauschii seeds reduced. All the results were significantly different from the control (CK) since the second day ( p < 0.05). During the aging process, the seed relative water content (RWC), relative electric conductivity (REC), and thiobarbituric acid (TBARS) level increased, while the superoxide dismutase (SOD) gradually decreased after second day of seed aging. In addition, the aging treatment also caused a continuous decrease in the endogenous gibberellin (GA 3 ) content and a continuous increase in the abscisic acid (ABA) content of the seeds. Thus, a sharp decrease in the GA 3 /ABA ratio was evident. Finally, the study revealed that the germination inhibitors of A. tauschii were mainly concentrated in the glumes, which was revealed during seed aging. The results of the comprehensive analysis indicated that the changes of the above-mentioned internal factors eventually led to a rapid decline of the seed vigor of A. tauschii . Based on the results of the aging test, and the distribution characteristics of A. tauschii seeds in the soil seed banks, we recommend that soil solarization is one of the effective methods to eradicate the seed bank of A. tauschii .

Longevity of genepool maize seeds under model conditions

Aim. To determine genotypic features of seed longevity of different subspecieses of maize - carriers of the corresponding genes under model conditions. Methods. Accessions of the maize (Zea mays L.) gene pool: dent maize (subsp.indentata), semi-dent (subsp. semindentata), waxy (subsp.ceratina) wx, popcorn (subsp.everta), sweet maize (subsp.saccharata.) sh were investigated in the conditions of model experiment "accelerated aging". Results. The seed longevity of studied maize genotypes was established in the conditions of model experiment on indicators of germination energy, seed germination and morphophysiological indexes of sprouting. The applied conditions of accelerated aging had a negligible effect on the studied parameters, which corresponded to the initial stages of seed aging. Variations in morphophysiological indexes were observed. Conclusions. The highest sensitivity to accelerated aging was found for sweet (sh) and waxy maize (wx). Variation of morphophysiological parameters of seedlings in experimental and control variants, seed longevity of the studied varieties are discussed.Keywords: gene pool, seeds, maize, subspecies, longevity.

Effect of Natural Seed Aging on Root and Shoot Traits in Bread Wheat (Triticum aestivum L.) Cultivars

This study targeted to elucidate the effect of seed aging on germination and emergence rates with and shoot characteristics in wheat cultivars. For this purpose, different bread wheat cultivars stored for 7 years and non-stored were compared for coleoptile length, root mass, shoot mass, root length as well as germination and seedling emergence rates. Here, the evidence suggested that seed storage over a prolonged period affected root and Shoot growth, coleoptile length, seed germination, and seedling emergence rates adversely. By linking germination and emergence rates, the data presented here indicated that a reduction in emergence rate in long-term storage was higher than that in the germination rate. It was also found that there were significant variations among the wheat cultivars about investigated traits during long-term storage. However, the emergence rates of Kate A1 and Flamura 85 were not affected substantially by long-term storage. The study suggested future studies to focus on clarification of the process controlling natural seed aging as such knowledge allows clue the eventual consequences of long-term storage.

Barley Seeds miRNome Stability during Long-Term Storage and Aging

Seed aging is a complex biological process that has been attracting scientists’ attention for many years. High-throughput small RNA sequencing was applied to examine microRNAs contribution in barley seeds senescence. Unique samples of seeds that, despite having the same genetic makeup, differed in viability after over 45 years of storage in a dry state were investigated. In total, 61 known and 81 novel miRNA were identified in dry seeds. The highest level of expression was found in four conserved miRNA families, i.e., miR159, miR156, miR166, and miR168. However, the most astonishing result was the lack of significant differences in the level of almost all miRNAs in seed samples with significantly different viability. This result reveals that miRNAs in dry seeds are extremely stable. This is also the first identified RNA fraction that is not deteriorating along with the loss of seed viability. Moreover, the novel miRNA hvu-new41, with higher expression in seeds with the lowest viability as detected by RT-qPCR, has the potential to become an indicator of the decreasing viability of seeds during storage in a dry state.

Identification of Metabolomic Biomarkers of Seed Vigor and Aging in Hybrid Rice

BackgroundSeed deterioration during rice seed storage will lead to seed vigor loss, which adversely affects agricultural production, the long-term preservation of germplasm resources, and the conservation of species diversity. However, the mechanisms underlying seed vigor maintenance remain largely unknown. ResultsIn this study, 16 hybrid rice combinations were selected from four sterile lines and four restorer lines. Following artificial aging and natural aging treatments, the metabolite markers that could accurately reflect the aging degree of the hybrid rice seeds were identified based on the germination percentage and metabolomics analysis by gas chromatography-mass spectrometry. Significantly differences in the degree of seed deterioration were observed among the 16 hybrid rice combinations tested, with each restorer and sterile lines after storage having the different germination percentage. The hybrid rice combination with the storage-resistant restorer line Guanghui122 exhibited the highest germination percentage under both natural and artificial storage. A total of 89 metabolic peaks and 56 metabolites were identified, most of which were related to primary metabolism. Interestingly, the content of galactose, gluconic acid, fructose and glycerol in the seeds increased significantly during the aging process. Absolute quantification indicated that galactose and gluconic acid were very significantly negatively correlated with the germination percentage of the seeds under the different aging treatments. The galactose content was significantly positively correlated with gluconic acid content. Additionally, while the relative content of raffinose did not change much during storage, a significant positive correlation between raffinose and the germination rate of the artificially aged seeds before storage was detected.ConclusionBased on the metabolomics, metabolite markers which could accurately reflect the aging degree of hybrid rice seeds were identified. Galactose and gluconic acid were very significantly negatively correlated with the germination percentage of the seeds which suggested that these metabolites could constitute potential metabolic markers of seed aging. These findings are of great significance for the rapid and accurate evaluation of seed aging, the determination of seed quality, and the development of molecular breeding approaches for high-vigor rice seeds.

Priming Fresh and Aged Seed of Soybean (Glycine max L.)

Background: High and stable production requires quality seed. Seed quality is the basis of efficient crop production and farmers need such seeds for optimum yield production. Therefore, various procedures are applied in seed production technology that aim to improve not only the germination of seeds but also the speed of its germination. These methods can reduce of seed aging and the effects of different agroecological factors. Methods: For research the impact of priming used seed aged seven months (fresh seeds) and seed was nineteen months old (aged seed). The seed was treated with following solutions: potassium nitrate (1%), ascorbic acid (100mgl-1) and potassium chloride (1%) for 6 hours and then germinated at 25°C in 8 days. Result: The analysis showed that seed aging resulted in a decrease in its germination energy and germination. Moreover, time required for germination is prolonged, the lipid peroxidation intensity and content of free proline are increased and the amount of vitamin C is reduced. The results showed that the effect of priming is dependable on variety selection, seed age and treatments. Therefore, we can conclude that there is no universal use of one only primer, as it may not be suitable for each particular cultivar and can ultimately lead to a decrease in the germination energy and germination.

Relationship between mitochondrial changes and seed aging as a limitation of viability for the storage of beech seed (Fagus sylvatica L.)

Aging is one of the most fundamental biological processes occurring in all forms of eukaryotic life. Beech trees (Fagus sylvatica L.) produce seeds in intervals of 5–10 years. Its yearly seed yield is usually very low, so there is a need for long-term seed storage to enable propagation of this species upon demand. Seeds for sowing must be of high quality but they are not easy to store without viability loss. Understanding the mechanism responsible for seed aging is therefore very important. We observed the generation of reactive oxygen species (ROS) in mitochondria of embryonic axes and cotyledons of beech seeds during natural aging. The presence of ROS led to changes in compromised mitochondrial membrane integrity and in mitochondrial metabolism and morphology. In this study, we pointed to the involvement of mitochondria in the natural aging process of beech seeds, but the molecular mechanisms underlying this involvement are still unknown.

Climate change affects seed aging? Initiation mechanism and consequences of loss of forest tree seed viability

Key message Environmental stress resulting from rapid climate changes leads to the initiation of the seed aging process in mitochondria and peroxisomes. Seed storage methods limiting germinability loss are fundamental for forest future. Abstract Seed aging is a natural process. It decreases the seed germination rate, i.e. the process is essential for the plant’s life cycle. Aging involves a progressive accumulation of oxidative damage over time. One of the main plant responses to stress is an excessive production of reactive oxygen species (ROS), such as O 2 −• , H2O2 and •OH. If the concentration of ROS is too high, it causes damage of the structure of lipid membranes, proteins, carbohydrates, and DNA. Climate changes affect tree reproduction and may have long-term consequences in the form of reduced species dispersal and acquisition of new habitats. High temperatures accelerate the aging of seeds and decrease their viability. There is, therefore, an indisputable need to store forest reproductive material to maintain continuity of regeneration in farm forests. The quality of seeds subjected to long-term storage correlates negatively with ROS concentration, as ROS accumulation typically occurs in tissues experiencing oxidative stress. Therefore, to preserve forest genetic resources, it is particularly important to know the causes and sites of initiation of the aging process in seed cells, as well as to prevent the germination rate decrease by developing appropriate storage methods. The main organelles responsible for intracellular ROS production are mitochondria and peroxisomes. This article aims at verifying the causes of seed aging and determining its consequences for future forest regeneration due to climate changes. We review the literature on oxidative stress, as well as the sites where the tree seed aging process originates, such as mitochondria and peroxisomes.

Analysis of Stored mRNA Degradation in Acceleratedly Aged Seeds of Wheat and Canola in Comparison to Arabidopsis

Seed aging has become a topic of renewed interest but its mechanism remains poorly understood. Our recent analysis of stored mRNA degradation in aged Arabidopsis seeds found that the stored mRNA degradation rates (estimated as the frequency of breakdown per nucleotide per day or β value) were constant over aging time under stable conditions. However, little is known about the generality of this finding to other plant species. We expanded the analysis to aged seeds of wheat (Triticum aestivum) and canola (Brassica napus). It was found that wheat and canola seeds required much longer periods than Arabidopsis seeds to lose seed germination ability completely under the same aging conditions. As what had been observed for Arabidopsis, stored mRNA degradation (∆Ct value in qPCR) in wheat and canola seeds correlated linearly and tightly with seed aging time or mRNA fragment size, while the quality of total RNA showed little change during seed aging. The generated β values reflecting the rate of stored mRNA degradation in wheat or canola seeds were similar for different stored mRNAs assayed and constant over seed aging time. The overall β values for aged seeds of wheat and canola showed non-significant differences from that of Arabidopsis when aged under the same conditions. These results are significant, allowing for better understanding of controlled seed aging for different species at the molecular level and for exploring the potential of stored mRNAs as seed aging biomarkers.