Dynamic Changes in Membrane Lipid Metabolism and Antioxidant Defense During Soybean (Glycine max L. Merr.) Seed Aging

Dynamic transcriptome and metabolome analyses of two sweet corn lines under artificial aging treatment

BACKGROUND

Strong tolerance to seed aging is an important agricultural trait for sweet corn production. Previous studies have primarily focused on the QTLs for the seed vigor. However, there were few researches involving in the metabolome and transcriptome of artificial aging seeds.

RESULTS

Using two inbred lines with significant differences in seed artificial aging tolerance, RNA sequencing and non-targeted metabolomic analysis were employed to extensively evaluate transcripts and metabolites in seeds that underwent artificial aging. Fourteen common transcripts and 16 common metabolites with sustained differential expression were identified in the two lines, suggesting their potential necessity in seed response to artificial aging. Enrichment analysis of differentially expressed genes (DEGs) in the transcriptome at different stages revealed significant enrichment KEGG pathways, "Oxidative phosphorylation" was the common pathway in the 0d vs 3d comparison for K107 and L155. The identical enriched KEGG pathways were observed in the 3d vs 6d comparison for K107 and 0d vs 6d comparison for L155, indicating a slower transcriptomic response in the aging-tolerance line. DEGs at 0 days between the two lines had been enriched in the "Terpenoid backbone biosynthesis" and "Ribosome" pathways, while at 6 days, the enrichment pathway were "Sulfur metabolism", "Linoleic acid metabolism", and "Plant hormone signal transduction". A total of 312 differentially expressed metabolites (DEMs) were found at 0, 3 and 6 days after seed aging treatment, and they shared enriched metabolic pathway of "ABC transporters". The KEGG enrichment of DEGs and DEMs shared the common pathway, namely "Linoleic acid metabolism". Among these, the most abundant metabolites were Glutathione, Adenosine, Trehalose, and 10E,12Z-Octadecadienoic acid. Focusing on the ascorbate-glutathione pathway revealed that the difference in ROS production and the ROS scavenging capability mediated by glutathione S-transferase (GST) genes were important factors contributing to the differing seed aging tolerance in the two lines.

CONCLUSION

In summary, these results contribute to a deeper understanding of the overall mechanisms underlying artificial aging tolerance in sweet corn seeds. The findings of this study are expected to provide valuable insights for the storage of sweet corn seeds.

Physiological, biochemical, and biophysical changes in chia seeds during accelerated aging: implications for lipid composition and seed quality

Chia, an oilseed native to Mexico and Guatemala, is prized for its nutrition and versatile uses in food and industry. Ex situ conservation of chia seeds is vital, yet their high lipid content complicates long-term storage. This study investigates artificial aging's impact on chia seed quality, emphasizing oxidative stress effects on lipid composition, antioxidants, and physiological properties. Two chia genotypes -one with mixed seed colors (MN) and another exclusively white (WN)- were subjected to accelerated aging to analyze germination, growth, electrical conductivity, and biochemical and biophysical changes over time. Accelerated aging revealed stress tolerance in chia seeds but significantly impacted germination and biochemical composition. Germination decreased from 100 to 0% over 56 days, with reduced radicle and hypocotyl lengths, fewer normal seedlings, and more abnormal or dead seeds. Peroxide values rose significantly, from 1.81 to 6.50 meq.kg-1 (WN) and 0.85 to 3.22 meq.kg-1 (MN), while free fatty acids increased from 0.41 to 2.95% oleic (WN) and 0.40 to 3.18% oleic (MN). Tocopherol content decreased markedly, disrupting the antioxidant-prooxidant balance. These biochemical changes resulted in higher saturated fatty acids, reducing membrane fluidity, and increasing electrical conductivity from 129.26 to 399.25 μS.cm-1.g-1 (WN) and 177.06 to 500.81 μS.cm-1.g-1 (MN). Thermal properties analyzed by DSC highlighted transitions within -90 to 100 °C, while FTIR spectroscopy revealed viability-related changes, particularly in the 1740 cm-1 region. These findings underscore the impact of oxidative stress on seed quality, posing challenges for conservation and commercialization and emphasizing the need for strategies to mitigate storage-related deterioration.

Graphic abstract

Spermidine Revives Aged Sorghum Seed Germination by Boosting Antioxidant Defense

Seed aging has adverse effects on agricultural production, mainly because seed vigor is inhibited. Spermidine can improve seed vitality and germination ability to a certain extent and is essential for plant growth and plant response to stress. This study explored how spermidine counteracted aging effects on sorghum seed germination through antioxidant metabolism regulation. Aged seeds showed decreased vigor due to heightened reactive oxygen species (ROS) and diminished antioxidants. Applying spermidine notably enhanced aged seeds' germination and vigor by boosting antioxidant enzyme activity and curbing ROS. Integrated transcriptomic, proteomic, and metabolomic analyses demonstrated that the majority of differentially expressed genes following exogenous spermidine treatment in aged sorghum seeds were significantly enriched in pathways related to glutathione metabolism, phenylpropanoid, and flavonoid biosynthesis, resulting in increased expression of genes encoding peroxidase, chalcone synthase, and glutathione s-transferase. Exogenous spermidine facilitated the synthesis of peroxidases and glutathione transferases. Analysis of flavonoid pathway intermediates showed a notable increase in antioxidant metabolites like isoquercitrin, underscoring their role in oxidative stress resistance. This multi-omics strategy underscores Spd's role in boosting aged seeds' antioxidants, highlighting the molecular basis of seed aging and Spd's rejuvenating impact.

Characterizing the variation in safflower seed viability under different storage conditions through lipidomic and proteomic analyses

The aging of seeds seriously affects their yield. Vacuum and low temperatures have been shown to prolong seed life and delay seed senescence. However, the underlying mechanisms that control these processes in safflower have yet to be explored. Therefore, this study aimed to study the structural, physiological and biochemical changes that occur in safflower seeds stored for one year at different temperatures and sealing conditions. X-ray imaging, germination percentage determination, determination of water content, and TTC staining were utilized to analyze seed structure and viability. The structure of its outer surface was observed by scanning electron microscope, and the changes of catalase activity and malondialdehyde content were determined to understand its physiological and biochemical status. In addition, lipidomic and proteomic analyses were performed. The results showed that the germination percentage was improved under vacuum and low temperature conditions. Compared with high-temperature storage, low-temperature storage not only reduces the level of reactive oxygen species, but also facilitates the preservation of intact seed structure. Lipidomic analysis indicated the levels of PA reduced at low temperatures, while the content of PC, PE, PS, and PG exhibited an inverse correlation, increasing as temperatures decreased. Proteomic analysis identified two proteins (HH-013791-RA, HH-017308-RA) that may be involved in fatty acid metabolism and carbon metabolism respectively. Expression levels of these proteins were found to be lower at -18 °C, but increased with increasing storage temperatures. Storing safflower seeds under low-temperature and vacuum conditions significantly enhances germination rates and preserves seed structure by reducing reactive oxygen species levels. Two proteins (HH-013791-RA, HH-017308-RA) in the fatty acid metabolism and carbon metabolism pathways are temperature-regulated, and are involved in lipid metabolism, affecting seed structure and vitality.

Lipid remodeling and response mechanisms during the germination of aged oat seeds

BACKGROUND

The high fat content in oat seeds makes them susceptible to aging during storage, leading to reduced seed vigor, delayed germination, and even seed death. Much evidence suggests that lipid remodeling is closely associated with successful seed germination. However, the dynamic behavior and response mechanisms of lipids during the germination of aged oat seeds remain unclear. In this study, 'Monida' (aging-tolerant) and 'Haywire' (aging-sensitive), were used to investigate the lipid profiles in the embryo and endosperm and the dynamic transcriptomic differences in the embryo during the germination.

RESULTS

The results demonstrate that phospholipid alterations during the germination of aged seeds are more significant compared to unaged seeds, indicating that aging affects lipid remodeling during germination, particularly in the 'Haywire'. Further analysis revealed that the most critical lipid response events occurred at the end of germination stage II (32 h) in embryo, primarily regulated through the PLC-DGK pathway to modulate phospholipid and glycerolipid molecules. Specifically, transcripts of PLC, DGK, and DGAT were upregulated, promoting the generation of diacylglycerol (DG) from various phospholipids, which further increased the monogalactosyldiacylglycerol/digalactosyldiacylglycerol (MGDG/DGDG) ratio, thereby influencing membrane repair. Additionally, at 6 h of germination in aged seeds, PC(3:0/0:0) levels significantly decreased. Compared to 'Monida,' the aging-sensitive 'Haywire' seeds exhibited substantial production of PE(19:0/0:0) and PC(15:0/0:0) at 32 h of germination, which may be key factors contributing to the seed's sensitivity to aging and the significant reduction in germination percentage after aging. Therefore, PC(3:0/0:0), PE(19:0/0:0), and PC(15:0/0:0) could serve as important lipid metabolic markers in future studies on the mechanisms of oat seed vigor.

CONCLUSIONS

The findings of this study provide insights into the specificity of lipid remodeling and its response mechanisms during the germination of aged oat seeds, providing a theoretical foundation for the safe preservation of oat germplasm and the development of aging-tolerant varieties.

Shotgun proteomics profiling of chia seeds (Salvia hispanica L.) reveals genotypic differential responses to viability loss

Introduction

Exposure to elevated temperatures and relative humidity expedites the seed aging process, finally leading to seed viability loss. In this context, certain proteins play a pivotal role in safeguarding the longevity of seeds. However, the seedproteomic response to loss viability in Salvia hispanica L., commonly known as chia, remains incompletely understood.

Methods

This work explores the application of proteomics as a potent tool for uncovering molecular responses to viability loss caused by artificial aging in two chia genotypes, WN and MN.

Results

By using a quantitative label-free proteomics analysis (LC-MS/MS), 1787 proteins wereidentified in chia seeds at a 95% confidence level, including storage proteins, heat shock proteins (HSPs), late embryogenesis abundant proteins (LEA),oleosins, reactive oxygen species (ROS)-related enzymes, and ribosomal proteins. A relatively low percentage of exclusive proteins were identified in viable and non-viable seeds. However, proteins exhibiting differential abundancebetween samples indicated variations in the genotype and physiological status. Specifically, the WN genotype showed 130 proteins with differential abundancecomparing viable and non-viable seeds, while MN displayed changes in the abundance of 174 proteins. While both showed a significant decrease in keyproteins responsible for maintaining seed functionality, longevity, and vigor withhigh-temperature and humidity conditions, such as LEA proteins or HSPs, ROS, and oleosins, distinct responses between genotypes were noted, particularly in ribosomal proteins that were accumulated in MN and diminished in WN seeds.

Discussion

Overall, the results emphasize the importance of evaluating changes in proteins of viable and non-viable seeds as they offer valuable insights into the underlying biological mechanisms responsible for the maintenance of chia seed integrity throughout high-temperature and humidity exposure.

Integrated examination of the transcriptome and metabolome of the gene expression response and metabolite accumulation in soybean seeds for seed storability under aging stress

Soybean quality and production are determined by seed viability. A seed's capacity to sustain germination via dry storage is known as its seed life. Thus, one of the main objectives for breeders is to preserve genetic variety and gather germplasm resources. However, seed quality and germplasm preservation have become significant obstacles. In this study, four artificially simulated aging treatment groups were set for 0, 24, 72, and 120 hours. Following an aging stress treatment, the transcriptome and metabolome data were compared in two soybean lines with notable differences in seed vigor-R31 (aging sensitive) and R80 (aging tolerant). The results showed that 83 (38 upregulated and 45 downregulated), 30 (19 upregulated and 11 downregulated), 90 (52 upregulated and 38 downregulated), and 54 (25 upregulated and 29 downregulated) DEGs were differentially expressed, respectively. A total of 62 (29 upregulated and 33 downregulated), 94 (49 upregulated and 45 downregulated), 91 (53 upregulated and 38 downregulated), and 135 (111 upregulated and 24 downregulated) differential metabolites accumulated. Combining the results of transcriptome and metabolome investigations demonstrated that the difference between R31 and R80 responses to aging stress was caused by genes related to phenylpropanoid metabolism pathway, which is linked to the seed metabolite caffeic acid. According to this study's preliminary findings, the aging-resistant line accumulated more caffeic acid than the aging-sensitive line, which improved its capacity to block lipoxygenase (LOX) activity. An enzyme activity inhibition test was used to demonstrate the effect of caffeic acid. After soaking seeds in 1 mM caffeic acid (a LOX inhibitor) for 6 hours and artificially aging them for 24 hours, the germination rates of the R31 and R80 seeds were enhanced. In conclusion, caffeic acid has been shown to partially mitigate the negative effects of soybean seed aging stress and to improve seed vitality. This finding should serve as a theoretical foundation for future research on the aging mechanism of soybean seeds.

Comparative Proteomic Analysis of Ridge Gourd Seed (Luffa acutangula (L.) Roxb.) during Artificial Aging

Seed aging is a complicated process influenced by environmental conditions, impacting biochemical processes in seeds and causing deterioration that results in reduced viability and vigor. In this study, we investigated the seed aging process of ridge gourd, which is one of the most exported commercial seeds in Thailand using sequential window acquisition of all theoretical fragment ion spectra mass spectrometry. A total of 855 proteins were identified among the two groups (0 d/15 d and 0 d/30 d). The Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses of differentially expressed proteins revealed that in ridge gourd seeds, the aging process altered the abundance of proteins related to the oxidative stress response, nutrient reservoir, and metabolism pathway. The most identified DEPs were mitochondrial proteins, ubiquitin-proteasome system proteins, ribosomal proteins, carbohydrate metabolism-related proteins, and stress response-related proteins. This study also presented the involvement of aconitase and glutathione pathway-associated enzymes in seed aging, with aconitase and total glutathione being determined as possible suggestive biomarkers for aged ridge gourd seeds. This acquired knowledge has the potential to considerably improve growing methods and seed preservation techniques, enhancing seed storage and maintenance.

Influence of Nitrogen-Modified Atmosphere Storage on Lipid Oxidation of Peanuts: From a Lipidomic Perspective

The effect of nitrogen-modified atmosphere storage (NS) on peanut lipid oxidation was investigated in this paper. Non-targeted lipidomics was employed to detect the lipid metabolites in peanuts with the aim of exploring the mechanism of lipid oxidation in peanuts under different storage conditions. The results showed that compared with conventional storage (CS), NS significantly (p < 0.05) delayed the increase in acid value, carbonyl value, and 2-thiobarbituric acid value and the decrease in vitamin E content. However, the storage time has a much greater effect on lipid oxidation than the oxygen level in the storage environment. Lipidomics analysis revealed that there were significant differences in metabolite changes between CS and NS. NS reduced the decline of most glycerophospholipids by regulating lipid metabolism in peanuts. NS maintained higher levels of Diacylglycerol (DAG), sulfoquinovosyl diacylglycerol (SQDG), lysophophatidylcholine (LPC), lysophosphatidylethanolamine (LPE) and phosphatidylinositol (PI) compared to CS. This work provided a basis for the application of NS technology to peanut storage.

Integrated Transcriptomic and Metabolomic Analyses Identify Critical Genes and Metabolites Associated with Seed Vigor of Common Wheat

Seed aging is a common physiological phenomenon during storage which has a great impact on seed quality. An in-depth analysis of the physiological and molecular mechanisms of wheat seed aging is of great significance for cultivating high-vigor wheat varieties. This study reveals the physiological mechanisms of wheat seed aging in two cultivars differing in seed vigor, combining metabolome and transcriptome analyses. Differences between cultivars were examined based on metabolomic differential analysis. Artificial aging had a significant impact on the metabolism of wheat seeds. A total of 7470 (3641 upregulated and 3829 downregulated) DEGs were detected between non-aging HT and LT seeds; however, 10,648 (4506 up and 6142 down) were detected between the two cultivars after aging treatment. Eleven, eight, and four key metabolic-related gene families were identified in the glycolysis/gluconeogenesis and TCA cycle pathways, starch and sucrose metabolism pathways, and galactose metabolism pathways, respectively. In addition, 111 up-regulated transcription factor genes and 85 down-regulated transcription factor genes were identified in the LT 48h group. A total of 548 metabolites were detected across all samples. Cultivar comparisons between the non-aged groups and aged groups revealed 46 (30 upregulated and 16 downregulated) and 62 (38 upregulated and 24 downregulated) DIMs, respectively. Network analysis of the metabolites indicated that glucarate O-phosphoric acid, L-methionine sulfoxide, isocitric acid, and Gln-Gly might be the most crucial DIMs between HT and LT. The main related metabolites were enriched in pathways such as glyoxylate and dicarboxylate metabolism, biosynthesis of secondary metabolites, fatty acid degradation, etc. However, metabolites that exhibited differences between cultivars were mainly enriched in carbon metabolism, the TCA cycle, etc. Through combined metabolome and transcriptome analyses, it was found that artificial aging significantly affected glycolysis/gluconeogenesis, pyruvate metabolism, and glyoxylate and dicarboxylate metabolism, which involved key genes such as ACS, F16P2, and PPDK1. We thus speculate that these genes may be crucial in regulating physiological changes in seeds during artificial aging. In addition, an analysis of cultivar differences identified pathways related to amino acid and polypeptide metabolism, such as cysteine and methionine metabolism, glutathione metabolism, and amino sugar and nucleotide sugar metabolism, involving key genes such as BCAT3, CHI1, GAUT1, and GAUT4, which may play pivotal roles in vigor differences between cultivars.

Insights into mechanisms of seed longevity in soybean: a review

Soybean, a crop of international importance, is challenged with the problem of seed longevity mainly due to its genetic composition and associated environmental cues. Soybean's fragile seed coat coupled with poor DNA integrity, ribosomal dysfunction, lipid peroxidation and poor antioxidant system constitute the rationale for fast deterioration. Variability among the genotypes for sensitivity to field weathering contributed to their differential seed longevity. Proportion and density of seed coat, glassy state of cells, calcium and lignin content, pore number, space between seed coat and cotyledon are some seed related traits that are strongly correlated to longevity. Further, efficient antioxidant system, surplus protective proteins, effective nucleotide and protein repair systems and free radical scavenging mechanisms also contributed to the storage potential of soybean seeds. Identification of molecular markers and QTLs associated with these mechanisms will pave way for enhanced selection efficiency for seed longevity in soybean breeding programs. This review reflects on the morphological, biochemical and molecular bases of seed longevity along with pointers on harvest, processing and storage strategies for extending vigour and viability in soybean.