Search Results (164)

Citrus trees are mainly cultivated in acidic soils. Excessive manganese (Mn) is the second most limiting factor for crop productivity in acidic soils after aluminum toxicity. The roles of reactive oxygen species (ROS) and methylglyoxal (MG) detoxification systems in augmented pH-mediated amelioration of excessive Mn are poorly understood. ‘Sour pummelo’ (Citrus grandis (L.) Osbeck) seedlings were exposed to nutrient solution at a Mn concentration of 500 (Mn500) or 2 (Mn2) μM and a pH of 3 (P3) or 5 (P5). The increase in pH attenuated Mn500-induced increases in ROS production and MG and malondialdehyde accumulation in roots and leaves. Additionally, the increase in pH enhanced the coordinated detoxification capability of both ROS and methylglyoxal scavenging systems in these tissues under Mn500. These findings corroborated the hypothesis that augmenting pH enhances the capability of these tissues to detoxify ROS and methylglyoxal under Mn excess. Therefore, this study provided new evidence on the roles of ROS and MG detoxification systems in the augmented pH-mediated amelioration of oxidative damage in ‘Sour pummelo’ leaves and roots caused by Mn excess, as well as a basis for correcting Mn toxicity by augmenting soil pH. Full article

Micronutrient malnutrition persists as a global health burden, while conventional biofortification approaches suffer from low efficiency and environmental trade-offs. This study aimed to develop and evaluate a foliar-applied selenium–zinc nanocomposite (Nano-ZSe, a mixture of zinc ionic fertilizer and nano selenium) for synergistic Se/Zn co-biofortification in Brassica chinensis L., using a controlled pot experiment that integrated physiological, metabolic, molecular, and rhizosphere analyses. Application of Nano-ZSe at 0.18 mg·kg⁻¹ (Based on soil weight) not only increased shoot biomass by 28.4% but also elevated Se and Zn concentrations in edible tissues by 7.00- and 1.66-fold (within the safe limits established for human consumption), respectively, compared to the control. Mechanistically, Nano-ZSe reprogrammed the ascorbate-glutathione redox system and redirected carbon flux through the tricarboxylic acid cycle, suppressing acetyl-CoA biosynthesis and reducing abscisic acid accumulation. This metabolic rewiring promoted stomatal opening, thereby enhancing foliar nutrient uptake. Simultaneously, Nano-ZSe triggered the coordinated upregulation of BcSultr1;1 (a sulfate/selenium transporter) and BcZIP4 (a Zn²⁺ transporter), enabling synchronized translocation and the tissue-level co-accumulation of Se and Zn. Beyond plant physiology, Nano-ZSe improved soil physicochemical properties, enriched rhizosphere microbial diversity, and increased crop yield and economic returns. Collectively, this work demonstrates that nano-enabled dual-nutrient delivery systems can bridge nutritional and agronomic objectives through integrated physiological, molecular, and rhizosphere-mediated mechanisms, offering a scalable and environmentally sustainable pathway toward functional food production and the mitigation of hidden hunger. Full article

The antimicrobial resistance crisis necessitates novel therapeutics. Selenium nanoparticles (SeNPs) offer promise, but their precise bactericidal mechanism remains poorly defined. This study aimed to define the antibacterial action of SeNPs synthesized via a green method with ascorbic acid and sodium citrate. The resulting SeNPs were monodisperse (17.8 ± 0.66 nm), crystalline, and highly stable (zeta potential: −69.9 ± 4.3 mV), exhibiting potent bactericidal activity against multidrug-resistant E. coli. To generate a mechanistic hypothesis, we integrated phenotypic analyses with a preliminary, single-replicate proteomic profiling. Recognizing this as an exploratory step, we focused our analysis on proteins with the most substantial changes. This revealed a coherent pattern of a targeted dual assault on core cellular processes. The data indicate that SeNPs simultaneously induce oxidative stress while severely depleting key components of the primary antioxidant glutathione system; key detoxification enzymes—glutathione S-transferase and glutaredoxin 2—were depleted 18- to 19-fold, while the stress protein HchA was reduced by over 63-fold. Concurrently, the patterns point toward a crippling of central energy metabolism; iron–sulfur enzymes in the TCA cycle, including aconitate hydratase (8.1-fold decrease) and succinate dehydrogenase (13.9-fold decrease), were severely suppressed, and oxidative phosphorylation was impaired (e.g., 4.7-fold decrease in NADH dehydrogenase subunit B). We propose that this coordinated disruption creates a lethal feedback loop leading to metabolic paralysis. Consequently, this work provides a detailed and testable mechanistic hypothesis for SeNPs action, positioning them as a candidate for a potent, multi-targeted antimicrobial strategy against drug-resistant pathogens. Full article

Drought stress (DS) is a primary environmental factor that limits the production of ginger (Zingiber officinale Roscoe). Silica nanoparticles (SiNPs) have been shown to enhance drought resistance in ginger by modulating water relations. However, the specific impact of SiNPs on the antioxidant and glyoxalase system responses to DS remains unclear. To investigate the impact of SiNP100 on photosynthetic and antioxidant metabolism in ginger under DS, four treatments were designed in this study: control (CK), drought stress (DS), silica nanoparticles (SiNP100) application, and the combined treatment of DS and SiNP100 (DS + SiNP100). The results showed that SiNP100 alleviated DS-induced damage by improving photosynthetic parameters, chlorophyll content, and the efficiency of photosystems I and II. DS significantly increased the levels of reactive oxygen species (ROS), malondialdehyde (MDA), and methylglyoxal (MG), thereby inducing oxidative stress. SiNP100 mitigated this effect by reducing ROS accumulation and enhancing the activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT). Furthermore, SiNP100 boosted the ascorbate–glutathione (AsA-GSH) cycle by increasing the activities of key enzymes (APX, DHAR, MDHAR, and GR) and upregulating the expression of ZoDHAR2, ZoAPX1, and ZoGR2. This leads to higher ascorbate and glutathione levels in ginger. SiNP100 also bolstered the glyoxalase system, as evidenced by increased activities of glyoxalase I (Gly I) and glyoxalase II (Gly II), alongside the upregulation of ZoGLY1 expression, thereby promoting methylglyoxal (MG) detoxification. In conclusion, SiNP100 enhances drought tolerance in ginger by reinforcing the antioxidant defense system, AsA-GSH cycle, and methylglyoxal detoxification system, thereby protecting photosynthetic metabolism and promoting growth. Full article

Copper (Cu) and cadmium (Cd) are common co-occurring environmental pollutants inducing combined stress, which severely harms maize growth. Previous studies have confirmed the involvement of the ascorbate–glutathione (AsA-GSH) cycle in heavy metal stress tolerance, but the regulatory effect of NATCA on this cycle under Cu-Cd combined stress—especially during maize seed germination and root development—remains unelucidated. Exogenous folcisteine (NATCA, 3-acetylthiazolidine-4-carboxylic acid) can enhance plant tolerance to abiotic stress. This study investigated the role of NATCA, a novel plant growth regulator with antioxidant potential, in alleviating Cu-Cd combined stress in maize. Two maize (Zea mays L.) varieties—Jiuyuan 15 (Cu/Cd-tolerant) and Longfuyu 6 (Cu/Cd-intolerant)—were exposed to combined stress (80 mg·L⁻¹ CuSO₄ + 100 mg·L⁻¹ CdCl₂) with/without 20 mg·L⁻¹ NATCA. Germination and hydroponic experiments were conducted to investigate NATCA’s effects on seed germination, growth, root traits, photosynthetic characteristics, reactive oxygen species (ROS) metabolism, AsA-GSH cycle (ascorbate–glutathione cycle), and endogenous hormones under stress. The results showed that combined Cu/Cd stress inhibited seed germination (reduced vigor, rate, index), while NATCA significantly reversed these declines, increased tolerance index, lowered relative damage rate, and improved seed activity—with more pronounced effects on Longfuyu 6. Stress stunted seedling growth (reduced dry/fresh weight, water content; increased water deficit), whereas NATCA promoted growth (taller plants, less leaf chlorosis, more fibrous roots), enhanced dry matter accumulation, and improved water metabolism. Stress impaired root morphology (shorter length, smaller surface area/volume, fewer tips) and absorption capacity; NATCA improved root traits, stress tolerance, and vitality. Stress weakened ROS scavenging, but NATCA elevated antioxidant enzyme activity and non-enzymatic antioxidant content, strengthened AsA-GSH cycle-mediated ROS clearance, mitigated stress damage, and maintained intracellular ROS balance in maize seedling root. These findings not only reveal a new regulatory role of NATCA in enhancing heavy metal stress tolerance via the AsA-GSH cycle but also provide a potential eco-friendly strategy for improving maize production in heavy metal-contaminated soils. Full article

Lead (Pb) is a widespread environmental pollutant that severely threatens plant growth and development. While the mechanisms of Pb uptake and accumulation have been extensively studied in herbaceous plants, the glutathione (GSH)-mediated biochemical responses in woody species remain largely unexplored. This knowledge gap limits our understanding of the detoxification strategies of perennial plants with high phytoremediation potential. In this study, two Salix integra clones (P336 and P646) with contrasting Pb tolerance were used to investigate the temporal regulation of GSH metabolism under Pb stress. P336 displayed both early and sustained increases in cysteine (Cys), GSH, ascorbic acid (AsA), phytochelatins (PCs), and the activities of γ-ECS and APX, conferring stronger antioxidant and detoxification capacity than P646. Notably, glutathione reductase (GR) activity remained unchanged in both clones, indicating that GSH homeostasis was maintained mainly through de novo synthesis rather than GR-mediated recycling. These findings demonstrate that Pb tolerance in P336 is achieved through γ-ECS–driven de novo GSH biosynthesis, which sustains both the AsA–GSH cycle and PC synthesis for efficient ROS detoxification and Pb sequestration. By providing the first detailed evidence of GSH-centered detoxification dynamics in a woody phytoremediant, this study advances our mechanistic understanding of Pb tolerance in S. integra and highlights its application potential in the phytoremediation of Pb-contaminated environments. Full article

Low-temperature stress severely restricts cotton seed germination and seedling establishment, especially in early spring. Ascorbic acid (AsA) priming is a promising strategy to enhance stress tolerance, yet its mechanisms in cotton remain unclear. This study examined the effects of AsA priming on seed germination at 15 °C. Seeds were treated with 0, 25, 50, or 100 mg/L AsA for 3, 6, 12, or 24 h. Results showed that 50 mg/L AsA for 24 h significantly improved germination potential, rate, index, and promptness index (p < 0.05). Compared with water-primed seeds, AsA-primed seeds exhibited greater radicle length (+17.67%) and fresh weight (+136.26%) under chilling stress. This treatment markedly increased antioxidant enzyme activities, including POD (+196.74%), SOD (+43.81%), and CAT (+49.43%), while also promoting the accumulation of Ascorbate–Glutathione cycle-related enzymes and metabolites, thereby reinforcing the antioxidant defense system. Multidimensional statistical analyses further indicated that AsA enhanced root growth by stimulating antioxidant defenses while inducing a trade-off that slightly reduced fresh weight, suggesting a balance between growth and oxidative protection. Overall, AsA priming improves cotton seed cold tolerance by activating enzymatic and non-enzymatic antioxidant systems and mediating a growth–defense trade-off, underscoring its potential as an effective priming agent for early sowing under low-temperature stress. Full article

With the rapid development of industry and agriculture, soil heavy metal pollution has become increasingly severe. Copper (Cu) and cadmium (Cd) often co-occur in soils, exerting combined stress on crops. As a major food and feed crop, maize was studied under CuCd stress to assess the mitigating effects of exogenous Folcisteine (NATCA). Two varieties with contrasting tolerance (Jiuyuan 15 and Longfuyu 6) were subjected to composite stress (80 mg·L⁻¹ CuSO₄ + 100 mg·L⁻¹ CdCl₂), with or without 20 mg·L⁻¹ NATCA. The impacts on photosynthesis, reactive oxygen species (ROS) metabolism, the ascorbate–glutathione cycle, and endogenous hormones were investigated. The results showed that CuCd stress reduced the activities of RUBPCase and PEPCase, inhibiting CO₂ fixation, while NATCA application enhanced their activities and improved photosynthetic efficiency. Stress also induced ROS accumulation (elevated O₂·⁻ and H₂O₂) and elevated electrolyte leakage, whereas NATCA reduced oxidative damage and stabilized membrane integrity. Additionally, NATCA boosted both enzymatic and non-enzymatic antioxidant capacity in the ascorbate–glutathione cycle, improving ROS scavenging. Stress disrupted endogenous hormone balance, decreasing IAA, GA, and ZR, and increasing ABA. NATCA application restored hormone levels toward balance, promoting growth and enhancing tolerance to CuCd stress. These findings demonstrate NATCA’s role in improving maize resilience under heavy metal stress. Full article

Background: The escalating global salinization poses a significant threat to agricultural productivity, necessitating a thorough understanding of plant responses to high salinity. Pea sprouts (Pisum sativum), a nutrient-rich crop increasingly cultivated in salinized regions, serve as an ideal model for such investigations due to their rapid growth cycle and documented sensitivity to ionic stress. Methods: In order to understand the response of pea sprouts in physiological regulation, redox-metabolic adjustments, and transcriptome reprogramming under salt stress, we investigated the effects of high salt concentrations on the ascorbic acid–glutathione cycle, endogenous hormone levels, metabolite profiles, and gene expression patterns in it. Results: Our findings reveal early-phase antioxidant/hormonal adjustments, mid-phase metabolic shifts, and late-phase transcriptomic reprogramming of pea sprouts under salt conditions. In addition, a biphasic response in the ascorbic acid cycle was found, with initial increases in enzyme activities followed by a decline, suggesting a temporary enhancement of antioxidant defenses. Hormonal profiling indicated a significant increase in abscisic acid (ABA) and jasmonic acid (JA), paralleled by a decrease in indole acetic acid (IAA) and dihydrozeatin (DZ), underscoring the role of hormonal regulation in stress adaptation. Metabolomic analysis uncovered salt-induced perturbations in sugars, amino acids, and organic acids, reflecting the metabolic reconfiguration necessary for osmotic adjustment and energy reallocation. Transcriptomic analysis identified 6219 differentially expressed genes (DEGs), with a focus on photosynthesis, hormone signaling, and stress-responsive pathways, providing insights into the molecular underpinnings of salt tolerance. Conclusions: This comprehensive study offers novel insights into the complex mechanisms employed by pea sprouts to combat salinity stress, contributing to the understanding of plant salt tolerance and potentially guiding the development of salt-resistant crop varieties. Full article

Oxybenzone (OBZ), an organic ultraviolet filter, is an emerging contaminant posing severe threats to ecosystem health. Using tobacco (Nicotiana tabacum) as a model plant, this study investigated the alleviation mechanisms of exogenous silicon (Na₂SiO₃, Si) and bamboo-based biochar (Bc) under OBZ stress. We systematically analyzed physiological and biochemical responses, including phenotypic parameters, reactive oxygen species metabolism, photosynthetic function, chlorophyll synthesis, and endogenous hormone levels. Results reveal that OBZ significantly inhibited tobacco growth and triggered a reactive oxygen species (ROS) burst. Additionally, OBZ disrupted antioxidant enzyme activities and hormonal balance. Exogenous Bc mitigated OBZ toxicity by adsorbing OBZ, directly scavenging ROS, and restoring the ascorbate-glutathione (AsA-GSH) cycle, thereby enhancing photosynthetic efficiency, while Si alleviated stress via cell wall silicification, preferential regulation of root development and hormonal signaling, and repair of chlorophyll biosynthesis precursor metabolism and PSII function. The mechanisms of the two stress mitigators were complementary, Bc primarily relied on physical adsorption and ROS scavenging, whereas Si emphasized metabolic regulation and structural reinforcement. These findings provide practical strategies for simultaneously mitigating organic UV filter pollution and enhancing plant resilience in contaminated soils. Full article

Drought deficit inhibits oat growth and yield. Fulvic acid (FA) can enhance plant stress tolerance, but its effects on regulating the ascorbate–glutathione cycle, chlorophyll synthesis, and carbon–assimilation ability remain unclear. Therefore, this study aimed to elucidate the physiological mechanisms of the FA regulation of drought tolerance in oats and its relationship with growth and yield using the drought-resistant variety Yanke 2 and the drought-sensitive variety Bayou 9. The effects of FA on growth and yield, the antioxidant system, chlorophyll synthesis, and carbon–assimilation capacity of oats under drought stress were investigated by systematically assessing changes in morphogenesis, ascorbate–glutathione cycle, chlorophyll and its intermediates, carbon–assimilation enzyme activities, and carbohydrate metabolism. The results showed that under drought stress, FA treatment significantly promoted oat growth (leaf area, dry matter) and yield, elevated glutathione peroxidase, ascorbate peroxidase, glutathione reductase, and dehydroascorbate reductase activities, reduced ascorbic acid, and reduced glutathione content. In addition, FA increased chlorophyll, as well as magnesium protoporphyrin IX, protoporphyrin IX, and protochlorophyllin acid ester content, enhanced 1,5-bisphosphate ribulose carboxylase, 1,5-bisphosphate ribulose carboxylase enzyme, 1,7-bisphosphate sestamibiose heptulose esterase, 1,6-bisphosphate fructose aldolase, sucrose synthase, sucrose phosphate synthase, acid invertase, and neutral invertase activities, and increased sucrose, glucose, and fructose content. Overall, fulvic acid (FA) alleviates drought-induced damage in oats by enhancing the ascorbate–glutathione cycle, promoting chlorophyll biosynthesis, and improving carbon assimilation and carbohydrate metabolism. The drought-sensitive variety (Yanke 2) was more effective in application compared to the drought-resistant variety (Bayou 9). This research provides valuable insight into its potential as a biostimulant under abiotic stress. Full article

In Northeast China, waterlogging has emerged as a significant challenge due to climate change, particularly during the June–August period when spring maize (Zea mays L.), at the post-tasseling phase, impedes a comprehensive understanding of responses and the development of resistance technologies. 2-(3,4-dichlorophenoxy) triethylamine (DCPTA) is suitable for the entire lifecycle of various economic and food crops, improving crop quality and enhancing stress resistance. The study investigated the ear leaf photosynthesis in relation to the root antioxidant systems’ differential responses of spring maize to waterlogging among the tasseling (VT), vesicle (R2) and dough (R4) stages, and the exogenous DCPTA regulating effect. Results revealed that waterlogging inhibited root physiological activity due to oxidative damage. Consequently, the stomatal restriction and non-stomatal restriction on photosynthesis appeared successively, and R4 was the most sensitive stage. Pretreatment with DCPTA reduced stomatal restriction by maintaining water transfer to the leaf through maintaining root physiological activity via enhanced ascorbate–glutathione cycle. Delayed non-stomatal restriction appeared due to relatively stable chlorophyll content and photosynthetic activities, and VT stage exhibited the highest susceptibility to DCPTA. The study provides a necessary theoretical foundation for comprehending the physiological mechanisms underlying yield formation of spring maize under waterlogging stress in Northeast China, and offers valuable insights for the development of chemical regulation technology. Full article

The present study aimed to investigate the effects of exogenous carnitine treatments on maize seed germination by stimulating lipid metabolism and regulating the mitochondrial respiratory pathway. Maize seeds were grown as control, 5, 7.5, and 10 μM carnitine treatment groups in a germination chamber at 25 °C under dark conditions for 5 d. It was determined that carnitine treatments increased the germination rate (GR), germination index (GI), germination potential (GP), vigor index (VI), root and hypocotyl length, fresh weight (FW), and content of total soluble protein but decreased the total carbohydrate content. It was also found that it increased the activities of α-amylase, isocitrate lyase (ICL), and malate synthase (MS) enzymes, which are critical in the germination process, and upregulated the expression of ICL and MS genes. To clarify the potential of carnitine treatments to promote the participation of lipids in respiration in roots and hypocotyls, lipase, carnitine acyltransferases (CATI and CATII), and citrate synthase (CS) enzyme activities were examined, and significant increases in these activities were detected. It was also found that gene levels of respiratory enzymes cytochrome oxidase (COX), pyruvate dehydrogenase (PDH), and Atp synthase, lipase, and CS proteins were upregulated by carnitine treatment. In support of the enzyme and gene change findings, significant changes were determined in fatty acid contents, free carnitine, and long-chain acylcarnitine levels in seeds, roots, and hypocotyls depending on carnitine application. In roots and hypocotyls, carnitine treatments significantly increased glutamine synthase (GS) and glutamate dehydrogenase (NADH-GDH) activities and gene expression levels, which are closely related to the tricarboxylic acid cycle (TCA). It was also noted that all proteins analyzed at the gene expression level were upregulated by carnitine applications in seeds. In addition, significant increases were recorded in antioxidant enzyme ascorbate peroxidase (APX) and superoxide dismutase (SOD) activities and total ascorbate (AsA) and glutathione (GSH) contents in roots and hypocotyls, while decreases were determined in guaiacol peroxidase (GPX) and catalase activities. Significant changes were recorded in all parameters examined, especially with 7.5 µM carnitine application. The findings suggest that carnitine may promote the transport of fatty acids to mitochondrial respiration by accelerating lipid catabolism in five-day-old maize and contribute to seed germination and growth and development processes by activating other metabolic pathways associated with respiration in this process. Full article

Ascorbic acid (AA) and glutathione (GSH) play a pivotal role in health assessment, drug development, and quality control of nutritional supplements. The development of a new and efficient method for their detection is highly desired. In this work, we fabricated magnetic core–shell nanocomposites (Fe₃O₄@MnPc-NDs) by a one-pot hydrothermal method with citric acid and manganese tetraamino phthalocyanine (MnTAPc) as precursors. Fe₃O₄@MnPc-NDs exhibited enhanced peroxidase activity compared to bare Fe₃O₄ nanoparticles, enabling catalytic oxidation of colorless 3,3′,5,5′-tetramethylbenzidine (TMB) to blue ox-TMB in the presence of H₂O₂. Leveraging the antioxidant properties of AA/GSH to reduce ox-TMB, a colorimetric assay achieved a low detection limit of 0.161 μM for AA and 0.188 μM for GSH with broad linear ranges. Moreover, this method displayed high specificity against 12 interfering substances and excellent recyclability (>90% activity after five cycles). Finally, the Fe₃O₄@MnPc-NDs could act as an efficient colorimetric sensor for accurately detecting AA in genuine VC tablets and GSH in whitening serums with high accuracy. Therefore, Fe₃O₄@MnPc-NDs exhibited great potential in bioassay applications, benefiting from their outstanding sensitivity and high recycling rate. Full article

Water stress is one of the foremost global abiotic stressors limiting agricultural productivity. Biostimulants and bioactive compounds are emerging as promising tools to enhance crop stress tolerance. This study investigates the effects of Cytolan^® Stress, a novel seaweed-derived biostimulant, on the water stress tolerance of lettuce plants. Three application strategies were evaluated: priming, where the biostimulant is applied before the onset of stress to prepare the plants for adverse conditions; buffering, involving application at the onset of stress to mitigate its immediate effects; and detoxifying, where the biostimulant is applied after stress to aid in plant recovery. Biomass, stress-related parameters, antioxidant activity, osmoprotectant levels, and photosynthesis-related metrics were analyzed to elucidate its potential mechanisms of action. The results demonstrated that Cytolan^® Stress in priming and buffering applications significantly improved water stress tolerance, reducing biomass loss from 45% to only 25%. Moreover, the detoxifying treatment was the most effective, as plants showed biomass values similar to those of the control plants. The biostimulant reduced oxidative stress indicators while enhancing antioxidant defenses, including ascorbate (AsA)-glutathione (GSH) cycle, antioxidant compounds, and enzyme activities. In addition, Cytolan^® Stress preserved photosynthesis performance under water stress conditions. These findings highlight the potential of Cytolan^® Stress to mitigate drought stress effects in lettuce, offering broader implications for crop tolerance and resilience under water-limited conditions. Further studies are recommended to explore its efficacy across different crops and stress scenarios. Full article