Search Results (560)

Potato (Solanum tuberosum L.) is one of the most widely cultivated crops in the world; however, drought is a major constraint to its productivity. Arbuscular mycorrhizal fungi (AMF) have been shown to improve plant resistance under conditions of water stress. However, their effects on potato plants are poorly studied. The purpose of this study was to evaluate the potential of two AMF inocula (two different strains of the AMF species Rhizophagus irregularis with different origin: Southern Spain MI₁ and Tunisia MI₂) on potato tolerance to drought stress through the determination of growth parameters, photosynthetic parameters, and antioxidant systems, under well-watered (WW; field capacity) and drought stress (DS; 50% of field capacity) conditions. Therefore, the experiment consisted of two factors: AMF strain and watering regime. The results showed that under drought stress conditions, AMF inoculation considerably stimulated photosynthetic performance as compared with non-inoculated controls. Moreover, leaf superoxide dismutase (SOD) and catalase (CAT) activities of inoculated plants were higher in WW conditions, but unchanged in DS conditions. Inoculated plants had significantly higher ascorbate peroxidase (APX) and glutathione reductase (GR) activities than non-inoculated plants under DS conditions. Also, expression of some antioxidant enzyme genes were upregulated by inoculation. Lipid peroxidation content of inoculated plants was lower than that of non-inoculated. Furthermore, there was a high positive correlation between mycorrhizal root colonization (RC) and almost all the measured parameters. The results of this study indicated that AMF inoculation could enhance potato plant tolerance to water stress through the induction of antioxidant mechanisms implicated in scavenging oxygen-free radicals. Full article

Thai eggplant (Solanum melongena L. cv. Chao Phraya), a widely cultivated vegetable with increasing global demand, is highly susceptible to salinity stress, which can severely impair seed germination and early seedling development. This study investigated the effects of sodium nitroprusside (SNP), a nitric oxide (NO) donor, on seed germination and seedling growth under salt stress conditions. Seeds were pre-treated with SNP at concentrations of 0, 0.05, 0.1, and 0.2 mM for 24 h and subsequently germinated under saline conditions with NaCl solutions (0, 100, and 200 mM). SNP pre-treatment, particularly at 0.05 and 0.1 mM, significantly improved germination percentage and germination rate in seeds exposed to 200 mM NaCl compared to untreated controls. Increased NaCl concentrations induced oxidative stress in seedlings, as evidenced by elevated hydrogen peroxide (H₂O₂) accumulation, which in turn caused lipid peroxidation, reflected by higher malondialdehyde (MDA) levels. Salt stress significantly increased ascorbate peroxidase (APX) activity, whereas catalase (CAT) activity showed no significant change across treatments. Correlation analysis revealed that APX activity was positively correlated with oxidative stress markers (H₂O₂) and delayed germination (T₅₀/MGT), whereas CAT activity showed no significant correlation with these parameters. In contrast, elevated APX activity was strongly and negatively correlated with overall seedling growth and vigor (SVI/GI), indicating that the underlying stress condition had a detrimental effect on plant performance. Overall, SNP pre-treatment, particularly at 0.05 and 0.1 mM, significantly enhanced salt tolerance by promoting germination (increasing GP and reducing T₅₀/MGT) and improving seedling growth (SL and RL). This protective effect is associated with improved redox regulation and partial mitigation of oxidative damage, as reflected by changes in H₂O₂, MDA, and APX; however, excessive SNP concentrations may exert phytotoxic effects, highlighting the importance of optimal dosing. Full article

This study aimed to evaluate the effect of stress attenuators on the tolerance and antioxidant activity of watermelon cultivars under water deficit. The experiment was conducted in two stages, Stage I corresponding to water deficit levels (N1 = 0; N2 = −0.1; N3 = −0.2 MPa) and six watermelon cultivars. Stage II comprises two cultivars selected in Stage I (one sensitive and one tolerant) and the combination of water restriction with attenuators (T1 = 0.0 MPa (control), T2 = −0.2 MPa (water deficit), T3 = −0.2 MPa + hydropriming, T4 = −0.2 MPa + gibberellic acid, T5 = −0.2 MPa + salicylic acid, and T6 = −0.2 MPa + hydrogen peroxide). The concentration and exposure times of the attenuators were determined through preliminary tests. In Stage I, physiological and biochemical analyses were performed. In Stage II, in addition to these tests, hydrogen peroxide content, malondialdehyde levels, and the activity of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) were assessed. Water deficit impaired germination and seedling vigor of watermelon, with Crimson Sweet, Omaru, Charleston Gray, and Congo being the most sensitive cultivars, while Fairfax was the most tolerant. For Crimson Sweet, pre-germination treatments reduced oxidative stress and enhanced tolerance by stimulating antioxidant enzyme activity, with GA and H₂O₂ providing the most effective results. For Fairfax, greater tolerance was associated with osmotic adjustment through the accumulation of compatible solutes, a mechanism further enhanced by the use of attenuators. Full article

Betaphycus gelatinus, a member of the Eucheumatoideae, serves as the primary source for carrageenan extraction and has significant economic value. The growth and reproduction of B. gelatinus are significantly impacted by seasonal fluctuations in seawater temperature. To explore its adaptive mechanisms under temperature stress, we cultured the algae at 15 °C (Low temperature, LT), 27 °C (Medium temperature, MT), and 36 °C (High temperature, HT) for 2 h and conducted subsequent physiological, transcriptomics, and metabolomics analyses. The photosynthetic performance of B. gelatinus significantly declined under both LT and HT stress conditions. Carotenoid content increased significantly under LT conditions, while chlorophyll a showed no significant change. Phycocyanin and phycoerythrin decreased significantly under LT conditions, but there was no significant difference under HT conditions. Under LT stress, glutathione (GSH) levels, ascorbate peroxidase (APX) activity, and catalase (CAT) activity all increased significantly. Under HT stress, APX and CAT activities increased significantly, while superoxide dismutase (SOD) activity and malondialdehyde (MDA) levels remained unchanged. Transcriptomics and metabolomics analyses suggested that photosynthesis, carbohydrate metabolism, amino acid biosynthesis, porphyrin metabolism, and vitamin B6 metabolism are involved in the acute temperature stress response of B. gelatinus. Under both HT and LT, most genes in the targeted metabolic pathways were significantly downregulated (p < 0.05), while only a few were upregulated. Specifically, in carbohydrate metabolism, only nine genes were upregulated, while all others were downregulated. Moreover, all the genes involved in photosynthesis, photosynthetic carbon fixation, arginine biosynthesis, and porphyrin metabolism were downregulated. In contrast, only four genes involved in GSH metabolism, alanine, aspartate, and glutamate metabolism, and glycine, serine, and threonine metabolism were upregulated. These results suggest that temperature stress markedly suppresses the transcription of key genes in these pathways and that the few upregulated genes in these pathways may contribute to compensatory mechanisms or regulatory network reprogramming during stress responses. These findings help clarify how B. gelatinus adapts to different temperature stresses and provide a basis for developing improved germplasm to support stable production under climate variability. Full article

Chilling injury (CI) is a major constraint to the postharvest shelf-life of tomato fruit (Solanum lycopersicum L.), leading to severe quality deterioration, which is closely linked to cell membrane damage. While individual postharvest treatments with the elicitors, such as methyl salicylate (MeSA), methyl jasmonate (MeJA), and the nitric oxide donor sodium nitroprusside (SNP), alleviate cold stress, their synergistic potential in combination has not been systematically explored. The present study evaluated the postharvest efficacy of 1 mM MeSA, MeJA, SNP, and their combinations (MeSA + MeJA, MeSA + SNP, MeJA + SNP) on ‘Vivalto RZ’ tomato fruits stored for 20 days at 2 °C, followed by a 2-day shelf-life period at 20 °C. All treatments effectively mitigated quality loss and CI incidence compared to the control. Notably, the MeSA + SNP and MeJA + SNP combinations demonstrated the highest efficacy, resulting in the lowest CI indices (1.2–1.4 vs. 3.4 in control) and the best preservation of firmness and titratable acidity. This enhanced tolerance was correlated with improved membrane integrity (lower malondialdehyde content and ion leakage) and the strongest upregulation of the antioxidant system, specifically achieving the highest ascorbate peroxidase (APX) activity. The combined application of MeSA or MeJA with SNP exerts a synergistic effect that provides superior chilling tolerance, representing a highly effective and commercially viable strategy to extend the postharvest shelf-life of tomato fruit. Full article

Induced resistance in plants is a promising strategy for pest management, helping to reduce dependence on synthetic pesticides. However, no study has yet examined the interaction between Tetranychus urticae and Aronia melanocarpa, including host acceptance, performance, and antioxidant defence mechanisms. In this study, host acceptance of T. urticae was evaluated using two A. melanocarpa ecotypes: a non-cultivar (AMe) and the cultivated variety ‘Galicjanka’ (AGe). Leaf morphological traits (trichome density and length) and key life-history parameters of the mite (fecundity, egg development time, and larval duration) were assessed. Mite feeding effects on oxidative stress markers (hydrogen peroxide—H₂O₂; thiobarbituric acid reactive substances—TBARS) and antioxidant enzyme activity (guaiacol peroxidase—GPX ascorbate peroxidase—APX) were analysed by ecotype and infestation duration. Results showed low fecundity and prolonged development, indicating that neither ecotype is a preferred host for T. urticae. Ecotype-dependent differences in acceptance and mite performance suggest that variation in trichome density and biochemical traits may influence susceptibility. Baseline differences in H₂O₂ and TBARS imply a role in constitutive resistance, while their induction, accompanied by increased GPX and APX activity, highlights oxidative stress and antioxidant defences as key components of A. melanocarpa responses to mite attack. Full article

Drought is one of the most severe abiotic stresses limiting agricultural productivity and threatening global food security. As the central organelle responsible for photosynthesis and stress perception, the chloroplast is highly sensitive to drought, and its structural and functional stability directly determines plant adaptability. Recent studies have revealed that chloroplasts undergo pronounced ultrastructural alterations under drought stress, including thylakoid membrane shrinkage, disorganization of grana stacks, and accumulation of reactive oxygen species (ROS). Excessive ROS production causes oxidative damage to lipids, proteins, and nucleic acids, whereas moderate ROS levels act as retrograde signals to regulate nuclear gene expression. In parallel, calcium (Ca²⁺) oscillations and retrograde signaling pathways—such as those mediated by GENOMES UNCOUPLED PROTEIN1 (GUN), 3′-phosphoadenosine-5′-phosphate (PAP), and Methylerythritol cyclodiphosphate (MecPP)—integrate chloroplast-derived stress cues with nuclear responses. To counteract drought-induced damage, plants activate a series of antioxidant systems—both enzymatic (Superoxide Dismutase (SOD), Ascorbate Peroxidase (APX), Catalase (CAT)) and non-enzymatic (Ascorbic Acid (ASA), (Glutathione) GSH, tocopherols, carotenoids)—along with protective proteins such as fibrillins (FBNs) and WHIRLYs that stabilize thylakoid and membrane structures. In addition, autophagy and plastid degradation pathways selectively remove severely damaged chloroplasts to maintain cellular homeostasis. Exogenous substances, including melatonin, 5-aminolevulinic acid (ALA), and Zinc oxide (ZnO) nanoparticles, have also been shown to enhance chloroplast stability and antioxidant capacity under drought stress. In this review, we discuss the structural and functional changes in chloroplasts, signaling networks, and protective repair mechanisms under drought stress. Furthermore, we highlight future research prospects for enhancing plant stress resilience through multi-omics integration, application of functional regulators, and molecular design breeding. 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

Vegetable soybean is a major crop in China with significant economic value. However, it is prone to yellowing and browning during postharvest storage, which reduces quality, marketability, and competitiveness. ‘Tongdou No. 6’ was used to evaluate postharvest quality preservation through combined cold shock treatment and nanocomposite polymer packaging. The results demonstrate that the combined treatment effectively slows the green-to-yellow color change by significantly reducing chroma a* value, weight loss, and chlorophyll degradation. Additionally, it markedly reduces the accumulation of malondialdehyde (MDA) and reactive oxygen species (H₂O₂ and O₂·⁻), while decreasing the activities of polyphenol oxidase (PPO) and peroxidase (POD). The treatment also significantly enhanced the levels of antioxidant compounds, including ascorbic acid (AsA), total phenolics, and total flavonoids, and boosted the activities of key antioxidant enzymes—ascorbate peroxidase (APX), superoxide dismutase (SOD), phenylalanine ammonia-lyase (PAL), and catalase (CAT). Moreover, the combined application of cold shock and nanocomposite polymer packaging significantly enhanced the scavenging capacity against DPPH and hydroxyl (OH⁻) radicals. Overall, combining these two techniques effectively delayed senescence-related discoloration by activating the antioxidant system, regulating ROS metabolism, and reducing oxidative damage. This approach is highly effective in maintaining postharvest quality and offers a promising solution to the storage-induced deterioration of vegetable soybeans. Full article

Ultraviolet-A light-emitting diode (UVA-LED) irradiation is an emerging technology for biofortifying plants with enhanced nutraceuticals. This study firstly investigated effects of various doses (0-control, 16, 32, 48 J/cm²) on Chinese cabbage microgreens (CCM) quality, identifying 32 J/cm² as the suitable dose for improving total antioxidant capacity (TAC) of CCM. Based on this dosage, the following two irradiation patterns were compared: single irradiation (SI, single pulse of 32 J/cm²) and fractionated irradiation (FI; four pulses of 8 J/cm² each). Both FI and SI significantly enhanced CCM quality, though through distinct mechanisms. FI effectively promoted accumulation of biomass and vitamin C, with increases by 9.25% and 13.20%, respectively. Meanwhile, SI markedly enhanced 20.90% higher TAC than FI. This was achieved by elevating enzymatic (7.71% superoxide dismutase-SOD, 9.03% peroxidase-POD, 40% catalase-CAT, and 52.17% ascorbate peroxidase-APX) and non-enzymatic (18.89% total phenolics-TPC, 10.04% total flavonoids-TF, and 18.99% carotenoids) antioxidants. Additionally, both FI and SI significantly reduced the nitrate content. To our knowledge, this is the first study to demonstrate the effect of UVA-LED irradiation pattern on microgreens quality. These findings provide basic information for UVA-LED application in indoor agriculture and the food industry, emphasizing the importance of strategically selecting irradiation patterns to achieve specific production goals. Full article

Cobalt (Co) is an essential micronutrient for many organisms, but, at higher concentrations, it becomes harmful, primarily due to competitive interactions with other metal ions. Enzyme inhibition and disruption of nutrient homeostasis may lead to oxidative stress in Co-exposed cells. Compared to other heavy metals, such as Cd, Cu, Cr, Pb, or Ni, this element has been less studied in algae with respect to its toxicity and tolerance. Taking into account Co-induced oxidative stress and antioxidant response, the studies on algae usually did not cover a wider range of antioxidants and ROS-detoxifying enzymes monitored in one model. The aim of this study was to assess the impact of CoCl₂ on the model green microalga Chlamydomonas reinhardtii from a broader perspective. We monitored algal growth, photosynthetic pigment content, the maximum quantum yield of photosystem II (F_v/F_m), the efficiency of nonphotochemical quenching of chlorophyll fluorescence (NPQ), and oxidative stress markers (superoxide production, lipid peroxidation). The measured antioxidants included soluble thiols, ascorbate (Asc), proline (Pro), α-tocopherol (α-Toc), and plastoquinol (PQH₂-9). The superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) activities were also determined. Exposure to CoCl₂ resulted in increased levels of thiols, Asc, α-Toc, PQH₂-9, and CAT activity. At lower concentrations of CoCl₂, no increase in oxidative stress markers was observed, suggesting efficient antioxidant protection. On the contrary, exposure to higher concentrations of CoCl₂ caused the inhibition of growth and chlorophyll (Chl) synthesis, as well as the reduction in the Chl a/Chl b ratio, the F_v/F_m parameter, the efficiency of NPQ induction, and the levels of lipophilic antioxidants, along with an increase in lipid hydroperoxides. An interesting and novel result is the inhibitory effect of Co toxicity on state transitions in exposed algae. Full article

The induction of resistance in plants involves prior activation of physiological and biochemical systems in the face of external stimuli, promoting greater tolerance to biotic stresses. Faced with the growing challenge of emerging diseases in agricultural plants and the search for more sustainable phytosanitary practices, natural substances are promising alternatives. Xylopia frutescens, known as “pindaiba-da-folha-pequena”, native to the Brazilian Cerrado and traditionally used as an antimicrobial treatment, is still little-explored in the literature and presents potentially effective compounds for the control of plant diseases. This study characterized the chemical composition and thermal stability of the X. frutescens essential oil (XEO), while evaluating its physiological and phytotoxic effects and the potential for disease control in maize and cowpea plants. The main constituents found in X. frutescens essential oil were nopinone (13.75%), spatulenol (12.94%), myrtenal (12.47%), and β-pinene (11.02%). Thermogravimetric analysis indicated that X. frutescens is highly volatile, with a large mass loss at 94.74 °C. In bioassays, the oil preserved chlorophyll levels at adequate amounts and activated several antioxidant mechanisms, but also showed a dose-dependent phytotoxic effect. In vitro assays further confirmed its antifungal activity against key phytopathogens, supporting its potential use in disease control. A general increase in the activities of the enzymes superoxide dismutase (SOD), ascorbate peroxidase (APx) and—partially—chitinase (CHIT) was observed. Catalase (CAT) decreased in both maize and cowpea plants treated with this essential oil but was higher in untreated infected plants. Such enzymatic changes suggest that the oil acts as a natural elicitor of resistance, strengthening biochemical and physiological defenses. Finally, disease severities, as measured by AUDPCs, demonstrated significant reductions in the progress of maize “Curvularia leaf spot” (Curvularia lunata) and cowpea “Web blight” (Rhizoctonia solani). The results highlight the potential of X. frutescens essential oil as an active compound stimulating defense mechanisms for applications in sustainable agricultural systems. Full article

As an important bioactive signaling molecule, nitric oxide (NO) participates in the responses of plants to various environmental stresses. The aim of this study was to investigate the influence of exogenous NO on the growth and cadmium (Cd) accumulation of alfalfa (Medicago sativa) during early growth. The results showed that Cd significantly inhibited alfalfa seedling growth and induced membrane lipid peroxidation. Addition of sodium nitroprusside (SNP, as an NO donor) significantly promoted seedling growth and induced the mobilization of seed photosynthate reserves, leading to an increase in total soluble sugar (SS) and reducing sugar (RS) contents. Application of SNP mitigated membrane peroxidation damage caused by Cd stress by enhancing catalase (CAT), ascorbate peroxidase (APX), superoxide dismutase (SOD) and peroxidase (POD) activities in order to eliminate reactive oxygen species (ROS), thereby improving Cd resistance and increasing Cd accumulation in alfalfa. This promoting effect of SNP depended on its concentration; the most optimal SNP concentration to promote the growth and Cd absorption of alfalfa under Cd stress was found to be 200 µM. The fresh weight (FW), dry weight (DW) and Cd accumulation of seedlings treated with 200 µM SNP increased significantly by 23.10%, 30.32% and 82.50%, respectively, on the fifth day, compared with the Cd-only treatment. Full article

Tris(2-chloroethyl) phosphate (TCEP), as an organophosphate contaminant, poses a significant threat to the growth and development of plants, especially roots. This study aimed to clarify the mechanisms of TCEP’s toxicity and damage to root systems, as well as the mechanisms of its damage to the respiration and energy metabolism of alfalfa root cells. The results showed that TCEP obviously affected the root length, root surface area, root volume, and root diameter of alfalfa. With increasing stress intensity, the total mitochondrial respiration rate and Cytochrome C Oxidase (COX) pathway respiration rate progressively declined, while the Alternative Oxidase (AOX) pathway respiration rate and its proportion of total respiration gradually rose. In addition, adenosine triphosphate (ATP) content and root vigor were significantly reduced. Moreover, with an increase in TCEP concentration, root superoxide anion radical content in alfalfa root cells was significantly elevated, while superoxide dismutase (SOD) and catalase (CAT) activities were significantly lowered, and ascorbate peroxidase (APX) and peroxidase (POD) activities were significantly enhanced. The present study indicated that respiration was disrupted, causing a lack of ATP in root cells under TCEP. Both the overproduction of reactive oxygen species (ROS) from the mitochondrial respiratory electron transport chain (mECT) and the deficiency of ROS-scavenging enzymes caused ROS accumulation, which led to the destruction of the cell membrane structure and exacerbated the disruption of the respiratory metabolism. The disruption of the conversion and reuse of energy by TCEP affected root growth and development. Full article

Salt stress is a significant environmental factor influencing plant growth and development. Anoectochilus roxburghii is a valuable medicinal plant, but it is still unclear how it responds to salinity. In this study, A. roxburghii was used as experimental material to investigate its physiological mechanisms underlying salt stress resistance. Seedlings were subjected to various NaCl concentrations (0, 50, 100, 150, and 200 mmol/L), and changes in key physiological parameters were subsequently analyzed. The results indicated that under NaCl-induced salt stress, the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX), as well as soluble protein content, initially increased and then decreased, with peak levels observed between 100 and 150 mmol/L. Malondialdehyde (MDA) content exhibited a steady increase with rising salt concentration. Total chlorophyll content declined progressively, while anthocyanin content increased initially but decreased significantly when NaCl concentration exceeded 100 mmol/L. Additionally, the contents of total flavonoids and total phenolics decreased markedly at salt concentrations above 100 mmol/L. These findings suggest that A. roxburghii can tolerate salt stress up to 100 mmol/L for 24 h without exhibiting substantial physiological or morphological damage. This study provides a theoretical basis for analyzing the salt tolerance mechanism of A. roxburghii. Full article