The Opposite Roles of White Light in Regulating Germination of Fresh and Aged Seed in Tobacco

Light is one of the important environmental factors for seeds to evaluate whether the natural environment is appropriate for germination and subsequent seedlings emergence. The mechanism of light-mediated germination is mainly concerned with fresh seeds (FS) of model plants but is poorly understood in aged seeds. Here, the effects of light on germination of FS and naturally aged seeds (NAS) in tobacco and their relationship with plant hormones gibberellins (GA) and abscisic acid (ABA) were investigated. The results demonstrated that light promoted and inhibited the germination of FS and NAS, respectively. GA and ABA were involved in the germination control of NAS, as well as in FS. However, light suppressed GA signal and stimulated ABA signal in NAS, whereas it stimulated GA signal and suppressed ABA signal in FS. In addition, light stimulated the GA accumulation and reduction in ABA in FS while inhibiting the increase in GA level in NAS. Together, the present study demonstrates that light has opposite effects on the germination of FS and NAS, which are closely related to the metabolism and/or signaling of plant hormones ABA and GA.

Exogenous Antioxidants Enhance Seedling Growth and Yield of Artificially Aged Cabbage and Lettuce Seeds

Aged seeds exhibit compromised vigour in terms of germination, seedling emergence and growth, but this can to some extent be alleviated by invigoration treatments before sowing. This study aimed to investigate ageing rates and patterns in cabbage (Brassica oleraceae) and lettuce (Lactuca sativa) seeds and whether the beneficial effects of invigorating aged seeds with exogenous antioxidants translate to enhanced seedling performance. Seeds were artificially aged to 25% viability before soaking in 0.4 mM glycerol, 0.6 mM GSH and 0.2 mM trolox for cabbage, and 0.6 mM glycerol, GSH and trolox for lettuce; deionised water served as a control. After 14 days of sowing, seedling emergence percentage, mean emergence time, mean daily emergence, and time taken to 25% emergence were computed. Seedling vigour index, root and shoot dry weight, root:shoot ratio, leaf area, leaf area ratio, and leaf chlorophyll content were assessed 6 weeks after sowing. Furthermore, the photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (E), and chlorophyll fluorescence were measured 6 weeks after sowing. Notably, ageing resulted in the loss of seed vigour and viability at higher rates in lettuce than cabbage. Seed pretreatment with glycerol promoted seedling growth in both species and shoot dry weight in lettuce, while glycerol and GSH enhanced Pn, Gs and E in lettuce. Trolox also enhanced Pn and E in lettuce. The beneficial effects of the antioxidant treatments are thought to be associated with the protection of photosystems from oxidative stress and/or stimulation of enzymes involved in photosynthesis, possibly through an enhanced antioxidant defence system during the early development stages when seedlings are particularly vulnerable to stress.

Non-Destructive Identification of Naturally Aged Alfalfa Seeds via Multispectral Imaging Analysis

Seed aging detection and viable seed prediction are of great significance in alfalfa seed production, but traditional methods are disposable and destructive. Therefore, the establishment of a rapid and non-destructive seed screening method is necessary in seed industry and research. In this study, we used multispectral imaging technology to collect morphological features and spectral traits of aging alfalfa seeds with different storage years. Then, we employed five multivariate analysis methods, i.e., principal component analysis (PCA), linear discrimination analysis (LDA), support vector machines (SVM), random forest (RF) and normalized canonical discriminant analysis (nCDA) to predict aged and viable seeds. The results revealed that the mean light reflectance was significantly different at 450~690 nm between non-aged and aged seeds. LDA model held high accuracy (99.8~100.0%) in distinguishing aged seeds from non-aged seeds, higher than those of SVM (87.4~99.3%) and RF (84.6~99.3%). Furthermore, dead seeds could be distinguished from the aged seeds, with accuracies of 69.7%, 72.0% and 97.6% in RF, SVM and LDA, respectively. The accuracy of nCDA in predicting the germination of aged seeds ranged from 75.0% to 100.0%. In summary, we described a nondestructive, rapid and high-throughput approach to screen aged seeds with various viabilities in alfalfa.

The Effects of Ozone Exposure on Aged Soybean Seeds Stored in Different Packaging

This article describes an idea about improving the aged soybean seed quality through ozone application based on the consideration that the ozone's oxidative and reactive nature could preserve agriculture commodities during storage. Using soybean seeds that were naturally aged in room temperature storage (25±5°C) for two months, gaseous ozone's efficacy in rejuvenating the aged seeds was examined. The aged seeds were divided into three different packages: open container, polypropylene woven sack, and vacuum polyethylene plastic. Gaseous ozone at a capacity of 150 g/h was continuously exposed on packaged seeds during six months of storage under low temperature (18±5°C). The authors found that ozone in specific limit exposure could improve physiological characteristics and inhibit some chemical properties deterioration of aged soybean seeds during storage. Our technique allows for improvement in germination percentage and germination rate of aged seeds in the fourth month of ozone exposure (p<0.05). However, these physiological parameters decreased significantly in the sixth month of ozone exposure, signing that prolonged ozone exposure would lead to adverse effects due to excessive oxidation. The result also showed that ozone storage significantly retard the elevation of moisture and free fatty acid content of aged soybean seeds. The ozone effectiveness evaluation is confirmed in all packaging conditions, but the vacuum packaging offered better preservation on almost entirely seed quality parameters during storage, except for protein. This research result provides a promising technique to restore aged seed quality and can be used for better seed provision in the seed industry.

A simple new method for aged seed utilization based on melatonin-mediated germination and antioxidant nutrient production

Seed deterioration, coupled with a decrease in nutrients, is unavoidable following long-term storage, and these seeds are therefore used as livestock fodder. Here, we developed a simple, rapid and efficient method of producing high amounts of antioxidants from deteriorated seeds via melatonin-induced germination. Legume seeds were subjected to high humidity at 55 °C for 12–36 h to obtain aged seeds with a 40% germination rate and severely reduced antioxidant nutrition (total phenolics content, ferric reducing power and 1,1-diphenyl-2-picryhydrazyl (DPPH) radical scavenging capacity). Aged seeds were then treated with 0.1 mM melatonin, resulting in the production of sprouts with a higher total phenolics content (fivefold), greater ferric reducing power (sevenfold) and greater DPPH radical scavenging capacity (twofold) compared to the aged seeds. These findings suggest that melatonin treatment efficiently converted aged seed reserve residues into antioxidant nutrients, providing an alternative use for deteriorated seeds in food production.

Biochemical Investigations on Vigour Enhancement in Fresh and Aged Seeds Upon Seed Priming in Cowpea [Vigna unguiculata (L.) Walp.]

Background: Loss in seed quality that occurs from maturity in the field to storage, leads to seed deterioration. Storage of cowpea seeds under ambient, hot and humid conditions is very problematic since these conditions deteriorate seed quality faster. Seed deterioration is associated with many metabolic defects that occur due to changes in enzyme and protein levels. Method: The present study was performed to verify the effects of cowpea [Vigna unguiculata (L.) Walp.] seed priming (GA3, ammonium molybdate, Ca Cl2, KBr, Mg (NO3)2, ZnSO4, Hydro priming and dry non primed) with fresh and accelerated aged seeds.Result: The deterioration was rectified to the extent possible by the technique of seed priming. SDS PAGE profiling indicated the differential expression of proteins with seed priming. Esterase and peroxidase enzyme which were completely lost as a result of ageing showed reappearance after priming. The band intensity as well as the number of proteins induced by seed priming increased over control. Priming also restored the lost seed vigour in aged seeds due to reactivation of proteins in old seeds and expression of these proteins in priming treatments are related to priming induced proteins in contrast to their absence in the aged seeds which are necessary for germination and longevity of seeds. The present study concluded that priming with GA3 (100 ppm) and Ammonium Molybdate (10-3 M) for 24 hours in aged seeds of cowpea showed increase enzyme activity, restored almost entire protein profile and esterase and peroxidise isozyme profile as it allowed repair system to combat sub-cellular damage and activated synthesis of enzymes and proteins.

Comparative Time-Course Physiological Responses and Proteomic Analysis of Melatonin Priming on Promoting Germination in Aged Oat (Avena sativa L.) Seeds

Melatonin priming is an effective strategy to improve the germination of aged oat (Avena sativa L.) seeds, but the mechanism involved in its time-course responses has remained largely unknown. In the present study, the phenotypic differences, ultrastructural changes, physiological characteristics, and proteomic profiles were examined in aged and melatonin-primed seed (with 10 μM melatonin treatment for 12, 24, and 36 h). Thus, 36 h priming (T36) had a better remediation effect on aged seeds, reflecting in the improved germinability and seedlings, relatively intact cell ultrastructures, and enhanced antioxidant capacity. Proteomic analysis revealed 201 differentially abundant proteins between aged and T36 seeds, of which 96 were up-accumulated. In melatonin-primed seeds, the restoration of membrane integrity by improved antioxidant capacity, which was affected by the stimulation of jasmonic acid synthesis via up-accumulation of 12-oxo-phytodienoic acid reductase, might be a candidate mechanism. Moreover, the relatively intact ultrastructures enabled amino acid metabolism and phenylpropanoid biosynthesis, which were closely associated with energy generation through intermediates of pyruvate, phosphoenolpyruvate, fumarate, and α-ketoglutarate, thus providing energy, active amino acids, and secondary metabolites necessary for germination improvement of aged seeds. These findings clarify the time-course related pathways associated with melatonin priming on promoting the germination of aged oat seeds.

Effects of Fe-Zn-NA chelates priming on the vigour of aged hybrid rice seeds and the maintenance of priming benefits at different storage temperatures

The effects of seed priming with Fe-Zn-NA chelate (FeSO4&plus;ZnSO4&plus;niacinamide) and the longevity of the beneficial priming effects were investigated for aged seeds of hybrid rice cv. Lingyouhuazhan (LYHZ) and cv. Longxiangyou 130 (LXY130). As compared with untreated and hydroprimed seeds, Fe-Zn-NA chelate priming significantly enhanced germination energy (GE), germination percentage (GP), germination index (GI), vigour index (VI) and normal seedling rate (NSR), and increased seedling shoot height (SH) and seedling dry weight (DW) in both cultivars. After priming with Fe-Zn-NA chelates, the GP of LYHZ was 96.0&percnt;, which was 12.7 and 12.0&percnt; higher than hydroprimed and non-primed seeds, respectively. Similarly, the GP of LXY130 was 89.5&percnt;, significantly higher than the hydroprimed and non-primed seeds (by 11.5 and 10.0&percnt;, respectively). When stored at 25&deg;C, the benefits of Fe-Zn-NA chelate priming on seed vigour and viability was maintained for three months; while after six months storage, the GP of LYHZ and LXY130 was only 48.0 and 34.0&percnt;, respectively, which was significantly lower than the non-primed seeds (84.0 and 71.1&percnt;). When stored at 15 or 5&deg;C for six months, the germination potential of Fe-Zn-NA chelate-primed seeds was still high. The GP of LYHZ and LXY130 seeds was 94.4&percnt; and 77.8%, respectively, after storage at 15&deg;C, and 97.8&percnt; and 85.6&percnt; after storage at 5&deg;C. In conclusion, the Fe-Zn-NA chelate priming was an effective method to improve the vigour and viability of hybrid rice aged seeds; however, the duration of beneficial priming effects needs to be determined according to the storage temperature.

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.