Search Results (239)

Bangia fuscopurpurea is a marine alga with significant commercial value. Although a high-light adapted species, the productivity of its commercial cultivation is frequently limited by environmental light attenuation, resulting in the algae operating under energy-limiting, sub-saturating conditions. This study investigated its physiological responses and antioxidant defense mechanisms across a sub-saturating light gradient (20, 40, and 80 µmol photons m⁻² s⁻¹). We employed exogenous ascorbic acid (AsA) supplementation to evaluate the dynamic response of the ascorbate-glutathione (AsA-GSH) cycle. Without AsA supplementation, the 40 µmol photons m⁻² s⁻¹ condition supported redox homeostasis and the highest soluble protein accumulation. In contrast, the lowest irradiance (20 µmol photons m⁻² s⁻¹) restricted physiological performance. At 80 µmol photons m⁻² s⁻¹, which remained below the light saturation point, the algae experienced oxidative stress, indicated by elevated lipid peroxidation and hydrogen peroxide levels. The efficacy of exogenous AsA depended on these energy states. Under the highest tested irradiance (80 µmol photons m⁻² s⁻¹), AsA reduced malondialdehyde (MDA) and maintained electron transport capacity, but these effects were accompanied by a significant degradation of photosynthetic pigments. These findings imply an altered partitioning of cellular reducing power, where the demand for AsA regeneration might limit the resources available for biosynthetic pathways. The study highlights that antioxidant efficacy is constrained by the cellular energy availability, which limits simultaneous stress mitigation and growth in light-limited aquaculture environments. Full article

It is widely recognized that microbial inoculants (MI) and bio-organic fertilizers (BOFs) containing beneficial microorganisms can play an important role in improving orchard soil properties and enhancing fruit quality. However, insufficient data regarding the relevant fruit quality effects hindered the supplementary MI and BOFs in kiwifruit cultivation. Using conventional fertilization management as the control, this study investigated the impacts of supplementary applications of MI and BOFs at two gradient dosages on the harvest-time quality and cold storage characteristics of ‘Puyu’ yellow-fleshed kiwifruit. Regarding leaf physiological indices and soil pH, MI-3.0 and BOF-20 treatments significantly elevated total chlorophyll content at 60 days after flowering (DAF) (the fruit expansion stage). Leaf nitrogen (N), phosphorus (P) and potassium (K) contents declined gradually during fruit development, while MI-2.0 and BOF-10 treatments markedly promoted leaf P accumulation at 20–100 DAF. Additionally, the MI-2.0 treatment significantly reduced 20–40 cm subsoil pH, which is favorable for kiwifruit plants that prefer acidic and slightly acidic conditions. On the other hand, appropriate doses of MI and BOF treatments exerted a significant effect on improving the quality of kiwifruit at the ripening stage. These effects were mainly manifested in the increased single fruit weight, firmness, dry matter content and total soluble solids (TSSs) of kiwifruit following MI-3.0 and BOF-20 treatments. Furthermore, MI-3.0 and BOF-10 notably elevated the fructose and glucose contents in both flesh and core, as well as sucrose and ascorbic acid (AsA) contents in the flesh; MI-2.0 and BOF treatments significantly increased citric and malic acids in the core and quinic acid in the flesh. During cold storage, the BOF-20 treatment not only delayed the occurrence of the ethylene peak by 20 d and significantly reduced its peak value, but also alleviated the decline in total acid content at the middle storage stage (20–40 d). Additionally, MI-2.0 and BOF-20 treatments effectively delayed kiwifruit softening at the early storage stage (0–10 d), and MI treatments maintained a high AsA content in the core during 10–20 d of cold storage. MI and BOF fertilization treatments had little effect on the dynamic change trends of sucrose synthase (SuS), sucrose phosphate synthase (SPS) and acid invertase (AI) in kiwifruit during cold storage, only exerting significant effects at specific time points. In conclusion, supplementary applications of MI and BOFs could improve kiwifruit quality at the harvest stage by positively regulating the accumulation of dry matter, soluble sugars and organic acid contents, and also have the potential to enhance the storage performance of kiwifruit. These findings provide a scientific basis for establishing an effective fertilization regime for kiwifruit. Full article

Soybean mosaic virus (SMV) is a major constraint on global soybean (Glycine max (L.) Merr.) production, causing substantial economic losses worldwide. Despite these losses, the potential of resistance genes as a solution remains largely unexplored. In this study, the COPPER CHAPERONE FOR SUPEROXIDE DISMUTASE (GmCCS) was initially employed as a bait to screen the soybean cDNA library, leading to the identification of a protein homologous to Arabidopsis thaliana COP9 signalosome complex subunit 5B (AtCSN5B), designated as GmCSN5B. Quantitative real-time PCR (qRT-PCR) analysis revealed differential expression of GmCSN5B in the SMV-resistant (Qihuang No.1, QH) and susceptible (Nannong 1138-2, NN) variety following SMV-SC3 strain inoculation. Knockdown of GmCSN5B via Bean pod mottle virus (BPMV)-induced gene silencing (VIGS) significantly enhanced SMV resistance compared to control plants. This work further demonstrated that GmCSN5B can interact with the downstream GmVTC1 protein, which was potentially associated with ascorbic acid (AsA; Vitamin C) synthesis. Moreover, GmVTC1 also responded to SMV infection, and its knockdown led to a reduction in endogenous AsA levels within the host, thereby compromising the plant’s resistance to SMV. Together, these findings suggest that the GmCCS-GmCSN5B-GmVTC1 pathway in soybean modulates host resistance to SMV through the regulation of AsA synthesis. Full article

Tobacco (Nicotiana tabacum L.) is an economically important crop in China. The risk of cadmium (Cd) pollution is increasing, making the mitigation of Cd stress critical for the safe production of tobacco. Silicon (Si) has been demonstrated to enhance plant growth under heavy metal stress. To elucidate the physiological and biochemical mechanisms by which Si alleviates Cd stress in tobacco, this study conducted a hydroponic experiment with three replicates using tobacco variety Yunyan 87 and employed one-way analysis of variance (ANOVA) for statistical analysis. The effects of Si on tobacco growth and the antioxidant defense system under Cd stress were investigated. The results showed that Cd stress significantly inhibited tobacco growth, increased Cd accumulation, and induced oxidative damage. Si treatment alleviated Cd stress in tobacco, increased biomass, reduced Cd concentration in different plant organs, and decreased the Cd translocation factor and bioconcentration factor. Meanwhile, the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) in tobacco roots and leaves were significantly enhanced, while the activities of ascorbate peroxidase (APX) and glutathione reductase (GR) were also elevated. The accumulation of ascorbic acid (AsA) and glutathione (GSH) increased, and malondialdehyde (MDA) concentration decreased. Overall, these results demonstrate that Si mitigates Cd stress in tobacco by limiting Cd accumulation and transport and by coordinately activating both enzymatic and non-enzymatic antioxidant systems. Full article

Background/Objectives: Nature-inspired therapeutic strategies that promote biological regenerative mechanisms and replicate the native structural microenvironment conductive to formation of healthy tissue are increasingly recognized as a promising platform for skin tissue regeneration and wound healing. This study proposes an innovative design of novel multifunctional scaffolds composed entirely of natural components—gelatin, L-ascorbic (ASA) acid and allantoin—as a bioinspired approach for skin tissue regeneration through pro-regenerative, antimicrobial, and keratinocyte-supportive properties. Methods: The biocompatible, skin-adhesive scaffolds were prepared via a simple and environmentally friendly heat-induced crosslinking of gelatin with varying ASA contents, and by enriching the system with allantoin. The influence of ASA content on scaffold properties was investigated through characterization of their morphology, porosity, swelling behavior, skin tissue adhesion, and allantoin release potential. Biocompatibility was evaluated in vitro using human keratinocyte (HaCaT) cells, while antibacterial activity was assessed against Escherichia coli and Staphylococcus epidermidis. Results: The scaffolds revealed a highly porous, interconnected structure with tunable porosity (87.37–92.39%) and soft-tissue-matched mechanical properties (0.81–1.47 MPa). Incorporation of allantoin into the scaffolds enhanced their mechanical performance and swelling capacity. All scaffolds demonstrated antibacterial activity against both tested bacteria, supported keratinocyte viability and provided sustained release of allantoin for up to 76 h, confirming their multifunctional pro-regenerative potential. Conclusions: The novel gelatin/ascorbic acid scaffolds enriched with allantoin combine a porous replicated structure of native extracellular matrix, fluid absorption capacity, soft-tissue-like mechanical properties, stable skin tissue adhesion, cytocompatibility and antibacterial functionality with the pro-regenerative properties of allantoin, thereby representing a multifunctional and biologically inspired platform for advanced skin tissue regeneration and wound-healing applications. Full article

Heat stress, intensified by global warming, poses a great threat to plant growth and crop production. However, the molecular mechanisms underlying heat stress response (HSR) remain largely unclear. In this study, we identified and characterized SlFBX38, an F-box gene in tomato. SlFBX38 was predominantly expressed in leaves and fruits, and its expression levels were induced by heat stress and various phytohormones, including ABA, JA and SA. Subcellular location analysis revealed that SlFBX38 resides in both the nucleus and cytoplasm in N. benthamiana leaf cells, but it displays no transcriptional activity. Overexpression of SlFBX38 (OE) lines conferred enhanced heat stress tolerance, as evidenced by improved photosynthetic efficiency, elevated accumulation of ascorbic acid (AsA), stronger protective enzyme activities, and upregulation of HSR-related genes in SlFBX38-OE lines under heat stress condition. To identify potential interacting proteins, yeast two-hybrid (Y2H) library screening and further Y2H verification indicate that SlFBX38 may interact with SlbHLH058. Collectively, these findings establish SlFBX38 as a positive regulator of thermotolerance in tomato and provide a basis for further mechanistic studies of its role in HSR. Full article

Mature-green tomatoes are prone to rapid ripening and quality deterioration during the postharvest stage, highlighting the urgent need for environmentally friendly and efficient preservation technologies. This study investigated the synergistic regulatory effects of nano-SiO₂ and light quality (white light, W; blue light, B; red/blue mixed light, RB, 1:1) on postharvest appearance, physiological processes, and quality attributes in ‘Yu Zhu’ (Solanum lycopersicum L.), a tasty tomato cultivar with light-yellow fruit color. Mature-green fruits were treated with light quality in combination with nano-SiO₂ (pre-immersion in 1 mL/L nano-SiO₂ for 1 h, followed by periodic spraying with 0.5 mL/L nano-SiO₂ every two days). Key indicators—including ripening traits, flavor attributes, antioxidant capacity, and endogenous hormone metabolites—were monitored on their respective sampling days. The results revealed distinct light quality-dependent responses: (1) B-Si (B + nano-SiO₂) significantly delayed the breaker stage compared to W, maintained the lowest water loss, and exhibited the slowest softening rate. W-Si showed a significantly higher dry weight-to-fresh weight ratio than W. (2) RB-Si achieved superior flavor quality, with 11.47% soluble solids, 1.62% titratable acidity, and a sugar-to-acid ratio of 7.2—values markedly higher than those in RB. (3) RB-Si increased total phenolic (TP), flavonoids, and ascorbic acid (AsA) levels relative to RB, while enhancing total antioxidant capacity (T-AOC) and the activities of superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), with only slight suppression of ascorbate peroxidase (APX) activity. (4) Nano-SiO₂ differentially regulated hormonal metabolism depending on light quality: it activated the jasmonic acid (JA)–gibberellin (GA) pathway under W light, fine-tuned cytokinin (CK) metabolism under B light, and upregulated JA, GA, CK, and auxin under RB light. Moreover, RB-Si significantly reduced ACC accumulation compared to W, thereby delaying senescence. Collectively, RB-Si synergistically regulates endogenous hormone metabolism to simultaneously delay ripening, reduce water loss, maintain firmness, optimize flavor, and enhance antioxidant capacity. This study elucidates the interaction mechanism between nano-SiO₂ and light quality, providing theoretical and technical support for the green preservation of horticultural crops. Full article

Pitaya (Hylocereus undatus) is a typical Crassulacean Acid Metabolism (CAM) plant with strong drought tolerance but high sensitivity to low temperatures. In this study, the responses of pitaya cultivated in the karst areas of Guizhou Province in southwest China to drought and low temperature were examined in winter seasons. The stems of ‘Zihonglong’ pitaya were used as materials to investigate the physiological responses to cold temperatures of pitaya stems under different water conditions, so as to understand the effects of drought stress on the response to low temperatures. The results showed that the severity of chilling injury in pitaya stems was influenced by cold degree and duration and temperature variation. Under sustained low-temperature conditions, the lower the temperature and the longer the duration, the more severe the chilling injury, particularly at 4 °C and below. Drastic temperature rise after exposure to low temperature of 5 °C aggravated the damage, especially when the temperature rise exceeded 10 °C. Compared to normally irrigated plants, those subjected to drought pretreatment exhibited milder chilling injury and higher survival rates under a temperature shift from 5 to 20 °C. The drought-treated pitaya stems had significantly lower membrane leakage and malondialdehyde (MDA) and reactive oxygen species (ROS) contents compared with the well-watered control under different temperature increases starting from 5 °C. Drought significantly reduced soluble sugars and soluble proteins but increased proline under a temperature shift from 5 to 20 °C. It significantly enhanced the activities of catalase (CAT) and ascorbate peroxidase (APX) under temperature shifts from 5 to 10 or 20 °C, but had no significant effect on peroxidase (POD) and superoxide dismutase (SOD). Drought also significantly increased ascorbic acid (ASA) content but significantly reduced glutathione (GSH). It is concluded that a drastic post-cold temperature rise causes more severe damage than the cold temperature itself. Drought pretreatment increases the chilling tolerance of pitaya stems. This effect involves an enhanced ASA-GSH cycle, which strengthens ROS scavenging and prevents membrane damage. Full article

Silicon (Si) plays a crucial role in mitigating biotic and abiotic stress in crops, yet its effects on cucumber seed germination under drought stress remain unclear. This study investigated the impact of exogenous Si on the ascorbic acid-glutathione (AsA-GSH) cycle during cucumber seed germination under PEG-6000-induced drought stress. Seeds of the cucumber cultivar ‘Xinchun No. 4’ were used in this study. Na₂SiO₃ served as the silicon source, and drought stress was simulated using PEG-6000. The treatments included distilled water (CK), 10% polyethylene glycol (PEG), and PEG combined with five concentrations of silicon (1, 3, 5, 7, and 9 mM Si). Results showed that 10% PEG significantly inhibited seed germination and reduced antioxidant capacity. In contrast, 5 mM Si (5.0 Si + PEG) alleviated PEG-induced stress, reducing malondialdehyde (MDA) and proline (Pro) by 36.87% and 13.71%, respectively, and decreasing reactive oxygen species (ROS) accumulation. Specifically, H₂O₂ and O₂·⁻ contents declined by 20.00–41.76% and 14.29–27.27%, respectively. The 5.0 Si + PEG treatment also reduced soluble sugar content by 29.08% and 27.84% at 48 h and 72 h, respectively, while increasing soluble protein content by 9.97% and 10.30% at 6 h and 12 h. Additionally, it enhanced activities of dehydroascorbate reductase (DHAR), glutathione reductase (GR), and glutathione Stransferase (GST) by 15.00%, 17.48%, and 18.81%, respectively, and elevated ascorbic acid (AsA) content and the GSH/GSSG ratio. In conclusion, 5 mM Si alleviated drought stress by activating the AsA-GSH cycle and enhancing antioxidant defense, providing valuable insights for Si application in agriculture. Full article

Saline–alkali stress is one of the important abiotic stresses, which affect plant growth and development. However, the understanding of miRNA pathways in different saline–alkali stress is still limited. In order to better understand the salt–alkali stress response mechanism of wheat, we analyzed miRNA transcription levels in two wheat varieties differing in saline–alkali tolerance (Qingmai 6, QM, tolerant; Meisheng 0308, MS, sensitive) under mixed saline–alkali stress (150 mmol·L¹ and 300 mmol·L¹) for 7 days. High-throughput sequencing identified 11,368 miRNAs (106 conserved, 11,262 non-conserved), among which four miRNAs (miR9653b, miR5384-3p, miR9777, and miR531) exhibited a consistent expression trend across both varieties and all stress concentrations. Additionally, a potential miRNA-mediated regulatory network (including miR408 and miR1135) was predicted to regulate reactive oxygen species (ROS) metabolism via cytochrome P450, plant hormone signal transduction, and MAPK pathways. Saline–alkali-tolerant and sensitive wheat cultivars exhibited distinct miRNA expression patterns under stress. QM maintained higher contents of non-enzymatic antioxidants (ascorbic acid, AsA; reduced glutathione, GSH) and activities of key antioxidant enzymes (ascorbate peroxidase, APX; glutathione reductase, GR), which contributed to balanced ROS homeostasis and enhanced saline–alkali tolerance. Full article

Eutrema salsugineum is a model species for studying stress resistance, particularly extreme salinity, and is often compared with Arabidopsis thaliana. Previous research has shown that basal salicylic acid (SA) levels are significantly lower in E. salsugineum than in A. thaliana. In this study, subtractive hybridization revealed that SA-related genes were extensively induced in Arabidopsis but not in Eutrema. Using exogenous SA and the biosynthesis inhibitor paclobutrazol (PBZ), we further demonstrated that the low endogenous SA level in Eutrema significantly upregulates dehydroascorbate reductase (DHAR) and glutathione reductase (GR) gene expression, doubling the pools of total ascorbic acid and total glutathione. While SA treatment decreased the ratios of reduced ascorbic acid (ASA) to dehydroascorbate (DHA) and reduced glutathione (GSH) to oxidized glutathione (GSSG), PBZ treatment increased them, correspondingly modulating DHAR and GR activities and gene expression. The resulting enhancement of these key non-enzymatic antioxidants is a critical mechanism underpinning the superior salt tolerance of Eutrema. Full article

Low salinity tolerance during germination and early seedling establishment limits large-scale cultivation of halophytes for forage, food, restoration, and conservation purposes. This study evaluates the potential of redox priming to enhance salt tolerance in the perennial C₄ halophyte grass Urochondra setulosa, which could be used as a revegetation and phytoremediation crop for coastal saline lands. Fresh seeds were found to be non-dormant with ~90% mean final germination (MFG) in distilled water. Redox priming, including hydrogen peroxide (H₂O₂), melatonin (MT), sodium nitroprusside (SNP; a nitric oxide donor), and ascorbic acid (AsA), significantly accelerated the germination rate index (GRI) and reduced mean germination time (MGT) without altering MFG under non-saline conditions. Salinity severely suppressed germination, as unprimed seeds reached only ~1% MFG with ~99% germination reduction (GR) and near-zero germination stress tolerance index (GSTI) at 200 mM NaCl. All priming treatments significantly improved MFG, GRI, and GSTI and decreased GR, with H₂O₂ priming showing the highest amelioration. Ungerminated seeds from all treatments recovered ~90% germination capacity in water, indicating enforced dormancy owing to osmotic constraints. Salinity did not impair growth in unprimed seedlings. However, MT priming uniquely enhanced total length, leaf area, and seedling vigor index (SVI) at 200 mM NaCl, while MT and SNP priming resulted in the highest chlorophyll and carotenoid contents. Multivariate analyses confirmed MT’s consistent superiority across traits under stress. Thus, H₂O₂ priming optimizes germination, while MT priming improves seedling vigor and offers a practical, targeted strategy to improve early-stage salinity tolerance in U. setulosa for coastal revegetation and sustainable saline agriculture. Full article

Ascorbic acid (AsA) is a key antioxidant and nutrient in plants, regulating reactive oxygen species (ROS) levels and maintaining cellular redox homeostasis. The AsA recycling pathway sustains AsA pools by restoring its oxidized forms, ensuring intracellular balance. Among the enzymes involved, monodehydroascorbate reductase (MDHAR) is important for the regeneration of AsA from monodehydroascorbate. In this study, we analyzed the four MDHAR paralogs in Lactuca sativa using CRISPR/Cas9 to determine whether disruption of individual MDHAR genes could alter AsA levels in lettuce leaves. Unexpectedly, none of the knockouts caused long-term changes in leaf AsA content. Transcriptomic analyses at 14 and 28 days showed minimal effects on AsA recycling or biosynthesis genes, except MDHAR genes. However, several other genes indirectly implicated in AsA regulation displayed differential expression in all mutants compared to the wild type, suggesting the presence of a complex regulatory network. In particular, genes encoding transcription factors (TFs), such as mTERF15, COL9, UPBEAT1, NAC28, and NAC42, were differentially regulated in all MDHAR mutants compared to the wild type at 28 days. These findings indicate that, although AsA content remains unchanged, MDHAR single knockouts alter expression of other genes through which the plants may indirectly compensate to maintain redox homeostasis. Full article

L-ascorbic acid (ASA) is an essential micronutrient critical for antioxidant defense and metabolic regulation in animals. Unlike many vertebrates, Drosophila melanogaster possesses the ability to synthesize ASA endogenously, yet the regulatory mechanisms governing this biosynthesis remain unclear. 2-keto-L-gulonic acid (2KGA), a key precursor in industrial vitamin C production, has been shown to enhance ASA accumulation in plants, but its role in invertebrates is unknown. This study systematically investigated the effect of exogenous 2KGA supplementation on ASA biosynthesis in Drosophila. Fruit flies were reared on media with or without 2KGA (1.6 g/L; n = 30 per group) for 12 days, followed by ASA quantification via high-performance liquid chromatography (HPLC). Results showed that 2KGA treatment increased mean ASA content from 0.00853 ± 0.0012 to 0.01064 ± 0.0015 μg/fly (24.74% increase; p = 0.0194, r² = 0.558) compared to the control group, indicating that 2KGA acts as a metabolic regulator to promote ASA biosynthesis. Sex-separated analyses further revealed that this effect was primarily driven by male flies (p = 0.0057, r² = 0.879), whereas females showed no significant response (p = 0.1783), pointing to a sex-dependent regulation of 2KGA-mediated ASA biosynthesis. These findings provide the first evidence that 2KGA modulates ASA levels in an invertebrate disease model and suggest that fruit flies can serve as a useful platform to explore conserved redox-regulatory mechanisms relevant to human health and disease. Full article

Plant root growth and architectural modifications are well-documented responses to phosphorous (P) starvation. The spatiotemporal dynamics of hydrogen peroxide (H₂O₂) in mediating root development under P deficiency, especially in cereal crops like wheat, remain insufficiently understood. A nutrient solution experiment was conducted to grow two varieties of wheat, including SM15 and HG35, with the treatments of 0.005 and 0.25 mmol/L P supply. Exogenous H₂O₂ and its scavenger ascorbic acid (AsA), and a NADPH oxidase inhibitor diphenylene iodonium (DPI) were added. The distribution of reactive oxygen species (ROS) in roots were detected by chemical staining and fluorescent probe technology. Low P supply did not change the root dry weight and total root length, while it decreased the lateral root density. The increase in the primary root and lateral root growth in P-starved wheat coincided with more ROS in the cell wall of the elongation zone. ROS production and oxidative enzyme activity of P-starved roots increased significantly. Low H₂O₂ induced the formation of lateral roots and significantly increased lateral root density under low P conditions. High H₂O₂ significantly reduced lateral root density but stimulated the nodal root formation. Exogenous AsA or DPI addition reversed the promotion of root growth imposed under the low P treatment or H₂O₂ addition. Furthermore, exogenous H₂O₂ treatment reduced the inhibitory effect of the DPI treatment on nodal root formation. It is suggested that the involvement of ROS in the regulation of wheat root system architecture under low P supply. Full article