Increasing H2O2 Concentration Research Articles

Real-time live imaging of cytosolic hydrogen peroxide and Ca2+ of Marchantia polymorpha gemmalings reveal immediate initial responses of plant cells triggered by nonthermal plasma irradiation.

Cold atmospheric pressure plasma generators capable of generating plasma under normal pressure and temperature conditions have recently been developed, and their biological applications have been extensively studied. Plasma irradiation has been reported to affect plant germination and growth; however, the molecular mechanism underlying these effects and initial cellular responses to plasma irradiation remains poorly understood. To unravel the molecular and cellular mechanisms underlying the effects of plasma irradiation on plants, we have been establishing novel experimental systems using a model liverwort Marchantia polymorpha. We here focused on the initial responses of plant cells to plasma irradiation. To investigate immediate cellular responses following plasma irradiation, we developed a new plasma device that allows irradiation under a microscope. Through integration with live fluorescence imaging, we established an experimental setup to track, the dynamics of intracellular concentration of H2O2 and Ca2+ as representative initial cellular responses. We revealed that plasma irradiation induced a rapid and transient increase in intracellular concentration of H2O2 and Ca2+ in Marchantia gemmalings. Pharmacological analyses suggested that the long-lived reactive species, H2O2, generated by the plasma generator was directly delivered into the plant cells. Competitive inhibitors of Ca2+ channels abolished the Ca2+ rise, suggesting that plasma irradiation immediately activate plasma membrane Ca2+ channel(s) to induce Ca2+ influx. Importantly, this study marks the inaugural demonstration of real-time monitoring of cytosolic H2O2 and Ca2+ dynamics in plants, triggered by plasma irradiation.

Fe78Si9B13/MnO2 composite: a magnetic and efficient Fenton-like catalyst in degradation of methyl orange under activation of H2O2

Abstract A magnetic and efficient Fe78Si9B13/MnO2 composite was successfully fabricated by a facile hydrothermal method. This composite was employed as a Fenton-like catalyst for the degradation of methyl orange (MO) under activation of H2O2. The phase and morphology of the composite were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The experimental results reveal that the theoretical mass loading of Fe78Si9B13/MnO2 composite and H2O2 dosage have a significant effect on MO degradation. Fe78Si9B13/MnO2 composite effectively improved MO oxidation ability and could quickly decolorize the MO to 99.7 %. Decolorization efficiency increased with increasing H2O2 concentration from 0 % to 1.15 %. Additionally, a possible reaction mechanism of the coupling system was proposed.

HSP70 and APX1 play important roles in cotton male fertility by mediating ROS homeostasis

Male sterility is used in the production of hybrid seeds and can improve the breeding efficiency of cotton hybrids. Reactive oxygen species is closely associated with the tapetum and pollen development, but their relationship in cotton male fertility remains unclear. In this study, we comprehensively compared the cytology and proteome of the anthers from an Upland cotton (Gossypium hirsutum) material, Shida 98 (WT), and its nearly-isogenic male sterile line Shida 98A (MS). Cytology indicated delayed PCD in the tapetum and defects in microspores in MS anthers. And further studies revealed disruption of ROS homeostasis. Proteomic analysis identified proteins with differential abundance mainly being related to redox homeostasis, protein folding, and apoptotic signaling pathways. GhAPX1 interacted with GhHSP70 and played a crucial role in the development of cotton anthers. Exogenous application of HSP70 inhibitor increased H2O2 content and decreased the activity of APX1 and pollen viability. The GhAPX1 mutants generated by CRISPR/Cas9-mediated gene editing exhibited premature degradation of the tapetum, significant decrease in pollen viability, and significant increase in H2O2 content. Altogether, our results imply HSP70 and APX1 being the key players jointly regulating male fertility by mediating ROS homeostasis. These results provide insights into the proteins associated with male fertility.

Role of NF-κB signaling pathway in H2O2-induced oxidative stress of hiPSCs.

The balance between oxidation and antioxidation is crucial for the development of embryo. It is harmful to the early embryonic development if embryonic stem cells (ESCs) encounter the serious oxidative stress in vivo. Induced pluripotent stem cells (iPSCs) are very similar to ESCs and are the important cell source to replace ESCs for research and therapy. Studies show that iPSCs have better resistant ability to oxidative stress, but the involved mechanism remains unclear. In this study, we predicted that the NF-κB pathway might be involved in H2O2-induced developmental damage by network toxicology analysis. Then, the oxidative stress model was established with different concentrations of H2O2 to investigate the mechanism of NF-κB pathway in oxidative stress of human induced pluripotent stem cells (hiPSCs). The results showed as follows: With the increase of H2O2 concentration, the ROS level gradually went up leading to an increasing damage degree of hiPSCs; however, the MDA content was obviously high only in the 400μM H2O2 group; the activities of some antioxidant indexes such as SOD2 and T-AOC were significantly upregulated in the 100μM group, while most of antioxidant indexes showed downregulated tendency to different degrees with the increase of H2O2 concentration. The expression levels of P65, P50, IκB, SOD2, and FHC mRNA were upregulated in most H2O2-treated groups, showing a dose-dependent relationship. In subsequent experiments, the inhibitor of IκB-α phosphorylation, Bay11-7082, reversed the upregulation of P65, IκB, and FHC mRNA expression induced by 400μM H2O2. The protein levels of P65, p-P65, P50, p-P50, IκB, p-IκB, SOD2, and FHC were upregulated in most H2O2-treated groups. However, the upregulation induced by 400μM H2O2 could be reversed by BAY 11-7082, except for IκB and SOD2. In conclusion, H2O2 could promote the expressions and phosphorylations of NF-κB that could upregulate the expressions of its downstream antioxidant genes to minimize the damage of hiPSCs caused by oxidative stress. These results contribute to a fundamental understanding of the antioxidant mechanism of iPSCs and will further facilitate the application of iPSCs, as well as provide a reference for controlling the oxidative stress encountered in the early development stage of embryo.

Synthesis of histidine, serine and folic acid-functionalized and boron and iron-doped graphene quantum dot with excellent optical behavior and peroxidase-like activity for colorimetric and fluorescence detection of H2O2 in food

Low fluorescence under visible light excitation and catalytic activity limit many applications of graphene quantum dots in optical detection, biosensing, catalysis and biomedical. The paper reports design and synthesis of histidine, serine and folic acid-functionalized and boron and iron-doped graphene quantum dot (Fe/B-GQD-HSF). The Fe/B-GQD-HSF shows excellent fluorescence behavior and peroxidase-like activity. Excitation of 330 nm ultraviolet light produces the strongest blue fluorescence and excitation of 480 nm visible light produces the strongest yellow fluorescence. The specific activity reaches 92.67 U g−1, which is higher than that of other graphene quantum dots. The Fe/B-GQD-HSF can catalyze oxidation of 3,3′,5,5′-tetramethylbenzidine with H2O2 to form blue compound. Based on this, it was used for colorimetric and fluorescence detection of H2O2. The absorbance at 652 nm linearly increases with the increase of H2O2 concentration between 0.5 and 100 μM with detection limit of 0.43 μM. The fluorescence signal linearly decreases with the increase of H2O2 concentration between 0.05 and 100 μM with detection limit of 0.035 μM. The analytical method has been satisfactorily applied in detection of H2O2 in food. The study also paves one way for design and synthesis of functional graphene quantum dots with ideal fluorescence behavior and catalytic activity.

Design and synthesis of a novel chiral photoacoustic probe and accurate imaging detection of hydrogen peroxide in vivo.

Nanocatalytic medicine, which aims to accurately target and effectively treat tumors through intratumoral in situ catalytic reactions triggered by tumor-specific environments or markers, is an emerging technology. However, the relative lack of catalytic activity of nanoenzymes in the tumor microenvironment (TME) has hampered their use in biomedical applications. Therefore, it is crucial to develop a highly sensitive probe that specifically responds to the TME or disease markers in the TME for precision diagnosis and treatment of diseases. In this work, a chiral photoacoustic (PA) nanoprobe (D/L-Ce@MoO3) based on the H2O2-catalyzed TME activation reaction was constructed in a one-step method using D-cysteine (D-Cys) or L-cysteine (L-Cys), polymolybdate, and cerium nitrate as raw materials. The designed and synthesized D/L-Ce@MoO3 chiral nanoprobe can perform in situ, non-invasive, and precise imaging of pharmacological acute liver injury. In vivo and in vitro experiments have shown that the D/L-Ce@MoO3 probe had chiral properties, the CD signal decreased upon reaction with H2O2, and the absorption and PA signals increased with increasing H2O2 concentration. This is because of the catalytic reaction between Ce ions doped in the nanoenzyme and the high expression of H2O2 caused by drug-induced liver injury to produce ·OH, which has a strong oxidizing property to kill tumor cells and destroy the Mo-S bond in the probe, thus converting the chiral probe into an achiral polyoxometalate (POM) with PA signal.

One stone two birds: Endophytes alleviating trace elements accumulation and suppressing soilborne pathogen by stimulating plant growth, photosynthetic potential and defense related gene expression

In the present investigation, we utilized zinc nanoparticles (Zn-NPs) and bacterial endophytes to address the dual challenge of heavy metal (HM) toxicity in soil and Rhizoctonia solani causing root rot disease of tomato. The biocontrol potential of Bacillus subtilis and Bacillus amyloliquefaciens was harnessed, resulting in profound inhibition of R. solani mycelial growth and efficient detoxification of HM through strong production of various hydrolytic enzymes and metabolites. Surprisingly, Zn-NPs exhibited notable efficacy in suppressing mycelial growth and enhancing the seed germination (%) while Gas chromatography-mass spectrometry (GC-MS) analysis unveiled key volatile compounds (VOCs) crucial for the inhibition of pathogen. Greenhouse trials underscored significant reduction in the disease severity (%) and augmented biomass in biocontrol-mediated plants by improving photosynthesis-related attributes. Interestingly, Zn-NPs and biocontrol treatments enhanced the antioxidant enzymes and mitigate oxidative stress indicator by increasing H2O2 concentration. Field experiments corroborated these findings, with biocontrol-treated plants, particularly those receiving consortia-mediated treatments, displayed significant reduction in disease severity (%) and enhanced the fruit yield under field conditions. Root analysis confirmed the effective detoxification of HM, highlighting the eco-friendly potential of these endophytes and Zn-NPs as fungicide alternative for sustainable production that foster soil structure, biodiversity and promote plant health.

Obróbka dla przemysłu ekstrakcji oliwy z oliwek poprzez zastosowanie peroksy-elektroutleniania

This study aimed to assess the effectiveness of peroxy-electrooxidation (PEO) for treating wastewater from the olive pomace oil extraction industry. The response surface methodology was utilized to optimize the efficiency of the PEO process under varying conditions of electrolysis time, current density, and hydrogen peroxide (H2O2) dosage. Appling graphite/aluminum sheets as cathode/anode in the treatment process showed that the concentration of H2O2 directly affected the efficiency of total phenolic compounds (TPh) removal. It was observed that at an H2O2 concentration of 15 g L-1, the removal efficiency was less than 80%. The removal of chemical oxygen demand (COD) is mainly influenced by the dosage of H2O2 and the reaction time. The experiments conducted on the PEO processes with graphite/iron sheets showed that the highest removal of TPh was achieved with an H2O2 dosage of 30 g L-1 and an intermediate reaction time of 30 minutes. Current density also had an impact on TPh removal. Regarding COD removal, the results showed that the highest removal rates were attained with increased H2O2 concentrations, but reaction time was a positive factor, with better results obtained with 30 and 50 minutes. The PEO is recommended as a pre-treatment for TPh removal but not for COD and other treatment processes should be evaluated.

Effects of hydroxyl radical oxidation on the stability and biochemical functions of rex rabbit meat

Reactive oxygen species (ROS)-generating system in muscle food is an important factor as it greatly influences shelf life and quality of meat. In this study, whole muscle homogenate was used as the research object, and the Fenton reaction system as an inducer was established for analyzing the effect of oxidation on Chuanbai Rex and Hyla rabbits meat. The homogenates were exposed to varying concentrations of hydrogen peroxide (H2O2, 0, 2, 4, 6, 8, and 10 mmol/L), the level of lipid oxidation of both breeds increased with the increased H2O2 concentration, while Hyla rabbits was higher. Oxidation and molecular aggregation of myofibrillar protein (MP) was observed in both breeds, including formation of carbonyl compounds, depleted sulphydryl, and increased hydrophobicity while fluorescence decreased. After oxidation, the loss of amino acids was higher in Hyla (16%) than in Rex rabbits (11%). Cys content was identified as the most discriminant parameter capable of elucidating the variations between the two breeds under this oxidation system.

A comprehensive investigation of the continuous oxidation of pyrrhotite by micromolar hydrogen peroxide in near neutral and acidic solutions

Pyrrhotite oxidation poses a big threat to water environment duo to its high potential for generating pollutants. Hydrogen peroxide, commonly found in natural water at micromolar concentrations, possesses much more aggressive oxidation ability than oxygen and can complicate the pyrrhotite oxidation process. Here, the effects of micromolar H2O2 on the biotic and abiotic oxidation of pyrrhotite were examined at pH 1.93 and 6.45, respectively. Pyrrhotite oxidation was much more severe in acidic solutions compared to near neutral solutions. Jarosite with a high Fe/S molar ratio was widely detected in the precipitate collected in acidic solutions, and the introduction of external H2O2 influenced the crystallinity of jarosite. A layer of iron-deficient iron-sulfur oxide formed on the surface of pyrrhotite prevents its continuous oxidation, and the presence of Acidithiobacillus ferrooxidans enhanced this situation by promoting the release of Fe from the pyrrhotite. Additionally, the presence of external micromolar H2O2 also determined the elemental state on pyrrhotite surface, as it found that the contribution of Fe3+ and S (S4+ and S6+) species on pyrrhotite surface increased with the increase of H2O2 concentration in the solutions, especially in the presence of Acidithiobacillus ferrooxidans.

Exogenous application of gibberellic acid reduces antioxidant capacity of leaves, resulting in increased Tipburn damages in Lisianthus cultivars

Tipburn (calcium (Ca) deficiency disorder of new leaf tips) is a severe problem in horticultural crop production. Studies have focused on the fact that tipburn commonly occurs during bolting and shown that plants exhibited greater tipburn damage than the control when bolting was induced using exogenous gibberellic acid (GA). However, why exogenous GA application enhances tipburn damage and why tipburn occurs during bolting remains unclear. To address this knowledge gap, we investigated the occurrence of tipburn, Ca concentrations in each organ, antioxidant capacity (superoxide dismutase (SOD) and catalase activity), and gene expression in three lisianthus cultivars (‘Umihonoka’ (UH), ‘Reina White’ (RW), and ‘Voyage Peach’ (VP)), where bolting was induced through exogenous active GA application (GA treatment) and discussed the cause of tipburn occurring during bolting. The incidence and severity of tipburn in the GA treatment were significantly higher than those in the control group in all cultivars. The Ca concentrations in the top leaves of the GA treatment were similar to or higher than those in the control treatment for all cultivars. In contrast, SOD activity in VP was significantly lower in GA treatment than that in the control, which was consistent with the results of SOD-CuZn expression. Additionally, significantly lower catalase activity at GA treatment were detected in the UH and RW than at the control. Recent studies have reported that reactive oxygen species and antioxidants significantly affect the appearance of blossom-end rot. Therefore, exogenous GA application decreased the antioxidant capacity of the upper leaves, resulting in increased tipburn damage. In addition, it is known that a decrease in antioxidant capacity and an increase in H2O2 concentration in leaves of Arabidopsis is a trigger for the initiation of bolting. Our findings provide important insight into the causes and ecological implications of tipburn during bolting.

Congo red dye degradation using Fe-containing mineral as a reactive material derived from waste foundry dust

This study investigated the applicability of industrial waste. The high affinity of Fe-based products is widely used for industrial effluents because of their capability to oxidize contaminants. Waste foundry dust (WFD) is an Fe oxide that has been investigated as a potential reactive material that causes the generation of reactive oxidants. We aimed to investigate the physicochemical properties of WFD and the feasibility in the Fenton oxidation process. The WFD was used as a catalyst for removing Congo red (CR), to evaluate the generation of •OH and dissolution of Fe during the oxidation process. The linkage of •OH generation by WFD with eluted Fe(II) through the Fe dissolution was found. The Fenton oxidation reaction, CR degradation was affected by H2O2 concentration, initial pH, WFD dosage, initial CR concentration, and coexisting anions. The CR degradation efficiency increased with an increase in H2O2 concentration and WFD dosage. In addition, chloride and sulfate in solution promoted CR degradation, whereas carbonate had a negative effect on the Fenton oxidation process. The elution of Fe promotes CR degradation, over three reuse cycles, the degradation performance of the CR decreased from 100 to 81.1%. For the Fenton oxidation process, •OH generation is linked to Fe redox cycling, the surface passivation and Fe complexes interrupted the release of reactive oxidants, which resulted in the degradation of the CR decreased. This study proposed that WFD can serve as catalysts for the removal of CR.

Efficiency of Hydrogen Peroxide and Fenton Reagent for Polycyclic Aromatic Hydrocarbon Degradation in Contaminated Soil: Insights from Experimental and Predictive Modeling

This study investigates the degradation kinetics of polycyclic aromatic hydrocarbons (PAHs) in contaminated soil using hydrogen peroxide (H2O2) and the Fenton process (H2O2/Fe2+). The effect of oxidant concentration and the Fenton molar ratio on PAH decomposition efficiency is examined. Results reveal that increasing H2O2 concentration above 25 mmol/samples leads to a slight increase in the rate constants for both first- and second-order reactions. The Fenton process demonstrates higher efficiency in PAH degradation compared to H2O2 alone, achieving decomposition yields ranging from 84.7% to 99.9%. pH evolution during the oxidation process influences PAH degradation, with alkaline conditions favoring lower elimination rates. Fourier-transform infrared (FTIR) spectroscopy analysis indicates significant elimination of PAHs after treatment, with both oxidants showing comparable efficacy in complete hydrocarbon degradation. The mechanisms of PAH degradation by H2O2 and the Fenton process involve hydroxyl radical formation, with the latter exhibiting greater efficiency due to Fe2+ catalysis. Gaussian process regression (GPR) modeling accurately predicts reduced concentration, with optimized ARD-Exponential kernel function demonstrating superior performance. The Improved Grey Wolf Optimizer algorithm facilitates optimization of reaction conditions, yielding a high degree of agreement between experimental and predicted values. A MATLAB 2022b interface is developed for efficient optimization and prediction of C/C0, a critical parameter in PAH degradation studies. This integrated approach offers insights into optimizing the efficiency of oxidant-based PAH remediation techniques, with potential applications in contaminated soil remediation.

Effects of radiation dose and dose rate on alginate and the use of radiation degraded alginate for peanut

Aqueous solutions of alginate (4 %) with or without hydrogen peroxide (0–2 % H2O2) were irradiated under a gamma Co-60 source. The effect of dose rate on the radiation scission yield (Gs) of resulting irradiated alginate was determined. At the dose of 20 kGy, the G(s) value of irradiated alginate decreased with the increase dose rate, suggesting that the irradiation at a suitable dose rate could further improve the radiation chemical yield of degradation. For the alginate irradiated at the same dose rate, G(s) value increased with the increase of H2O2 concentration. Average molecular weight (Mw) and polydispersity index (PI) of irradiated alginate rapidly decreased with the increase in dose and further decreased by addition of H2O2. The oligoalginate with Mw ~ 9800 g/mol was obtained by radiation degradation of 4 % alginate solution containing 2 % H2O2 at dose of 20 kGy. Radiation scission of glycoside bonds and formation of carbonyl groups (C=O) were indicated in UV and FTIR spectra of irradiated alginate. Peanut seedlings were fertilized with alginate and oligoalginate solutions, and the results showed that all growth parameters of the treated plants were better than those of the control. Furthermore, the oligoalginate prepared by gamma irradiation can be applied as a plant growth promoter for agriculture production.

Comprehensive analysis of MAPK gene family in upland cotton (Gossypium hirsutum) and functional characterization of GhMPK31 in regulating defense response to insect infestation

Key messageThe transcriptomic, phenotypic and metabolomic analysis of transgenic plants overexpressing GhMPK31 in upland cotton revealed the regulation of H2O2 burst and the synthesis of defensive metabolites by GhMPK31.Mitogen-activated protein kinases (MAPKs) are a crucial class of protein kinases, which play an essential role in various biological processes in plants. Upland cotton (G. hirsutum) is the most widely cultivated cotton species with high economic value. To gain a better understanding of the role of the MAPK gene family, we conducted a comprehensive analysis of the MAPK gene family in cotton. In this study, a total of 55 GhMPK genes were identified from the whole genome of G. hirsutum. Through an investigation of the expression patterns under diverse stress conditions, we discovered that the majority of GhMPK family members demonstrated robust responses to abiotic stress, pathogen stress and pest stress. Furthermore, the overexpression of GhMPK31 in cotton leaves led to a hypersensitive response (HR)-like cell death phenotype and impaired the defense capability of cotton against herbivorous insects. Transcriptome and metabolomics data analysis showed that overexpression of GhMPK31 enhanced the expression of H2O2-related genes and reduced the accumulation of defensive related metabolites. The direct evidence of GhMPK31 interacting with GhRBOHB (H2O2-generating protein) were found by Y2H, BiFC, and LCI. Therefore, we propose that the increase of H2O2 content caused by overexpression of GhMPK31 resulted in HR-like cell death in cotton leaves while reducing the accumulation of defensive metabolites, ultimately leading to a decrease in the defense ability of cotton against herbivorous insects. This study provides valuable insights into the function of MAPK genes in plant resistance to herbivorous insects.

Enzyme-Empowered "Two Birds with One Stone" Strategy for Amplifying Tumor Apoptosis and Metabolic Clearance.

Nanomedicine has reshaped the landscape of cancer treatment. However, its efficacy is still hampered by innate tumor defense systems that rely on adenosine triphosphate (ATP) for fuel, including damage repair, apoptosis resistance, and immune evasion. Inspired by the naturally enzymatic reaction of glucose oxidase (GOx) with glucose, here a novel "two birds with one stone" technique for amplifying enzyme-mediated tumor apoptosis and enzyme-promoted metabolic clearance is proposed and achieved using GOx-functionalized rhenium nanoclusters-doped polypyrrole (Re@ReP-G). Re@ReP-G reduces ATP production while increasing H2O2 concentrations in the tumor microenvironment through GOx-induced enzymatic oxidation, which in turn results in the downregulation of defense (HSP70 and HSP90) and anti-apoptotic Bcl-2 proteins, the upregulation of pro-apoptotic Bax, and the release of cytochrome c. These processes are further facilitated by laser-induced hyperthermia effect, ultimately leading to severe tumor apoptosis. As an enzymatic byproduct, H2O2 catalyzes the conversion of rhenium nanoclusters in Re@ReP-G nanostructures into rhenate from the outside in, which accelerates their metabolic clearance in vivo. This Re@ReP-G-based "two birds with one stone" therapeutic strategy provides an effective tool for amplifying tumor apoptosis and safe metabolic mechanisms.

Complex Formation between the Transcription Factor WRKY53 and Antioxidative Enzymes Leads to Reciprocal Inhibition.

The transcription factor WRKY53 of the model plant Arabidopsis thaliana is an important regulator of leaf senescence. Its expression, activity and degradation are tightly controlled by various mechanisms and feedback loops. Hydrogen peroxide is one of the inducing agents for WRKY53 expression, and a long-lasting intracellular increase in H2O2 content accompanies the upregulation of WRKY53 at the onset of leaf senescence. We have identified different antioxidative enzymes, including catalases (CATs), superoxide dismutases (SODs) and ascorbate peroxidases (APXs), as protein interaction partners of WRKY53 in a WRKY53-pulldown experiment at different developmental stages. The interaction of WRKY53 with these enzymes was confirmed in vivo by bimolecular fluorescence complementation assays (BiFC) in Arabidopsis protoplasts and transiently transformed tobacco leaves. The interaction with WRKY53 inhibited the activity of the enzyme isoforms CAT2, CAT3, APX1, Cu/ZuSOD1 and FeSOD1 (and vice versa), while the function of WRKY53 as a transcription factor was also inhibited by these complex formations. Other WRKY factors like WRKY18 or WRKY25 had no or only mild inhibitory effects on the enzyme activities, indicating that WRKY53 has a central position in this crosstalk. Taken together, we identified a new additional and unexpected feedback regulation between H2O2, the antioxidative enzymes and the transcription factor WRKY53.

MiR408 balances plant growth and heat response in rice

MicroRNAs are small noncoding RNAs that regulate gene expression by targeting complementary mRNA molecules. Among them, microRNA408 (miR408) is an ancient microRNA influencing plant growth and aiding in abiotic stress adaptation. We proved that miR408 sliced uclacyanin7 (UCL7) directly by degradome sequencing. However, the mechanisms underlying the balance between growth and stress response of rice (Oryza sativa L.) controlled by miR408 remain unclear. We conducted a study comparing Nipponbare (wild-type, WT) plants with miR408–3p-overexpression (miR408–3p-OX) and UCL7-overexpression (UCL7-OX) plants under normal and heat stress conditions. Through RNA-sequencing, physiological measurements, and phenotype examination, we observed that miR408 overexpression resulted in increased dry weight and grain yield, higher levels of ATP and non-structural carbohydrates (NSC), improved photosynthesis, and reduced H2O2 content, antioxidant enzyme activity, and ATPase activity in seedling plants compared to UCL7-OX plants. Additionally, the application of H2O2 scavengers, such as ascorbic acid (ASA) and dimethylthiourea (DMTU), further enhanced dry weight and photosynthesis by reducing H2O2 levels. Under heat stress conditions, miR408 overexpression sharply increased H2O2 content, antioxidant enzyme activity, ATP levels, and ATPase activity compared to UCL7-OX plants, thereby enhancing heat tolerance in rice seedlings. These findings suggest that miR408 and its target gene UCL7 participate in regulating energy homeostasis to achieve a balance between growth and heat response. This regulation involves modulating H2O2 levels and optimizing the relationship between the target of rapamycin (TOR) and SNF1-related protein kinase 1 (SnRK1) in rice.

Salt stress responses of microalgae biofilm communities under controlled microcosm conditions

Algal biofilms play an essential role in ecosystem functioning, but their physiological and biochemical changes during salt stress remain poorly understood. This study aimed at investigating how biofilm communities react to different salinity in a microcosm experiment and to offer insights into the potential effects of future freshwater salinization. Biofilm samples collected from Iriri River (Drâa basin, Southern Morocco) were exposed to water gradually enriched with sodium chloride to obtain three final concentrations (1, 10, and 30 g/L) over 14 days, and the changes were compared with control. Several biofilm responses were analyzed throughout the experiment, including biofilm biomass, changes in community structure and composition via eDNA metabarcoding, physiological feedback, biochemical parameters, antioxidant activities, non-enzymatic salt stress markers, osmoprotection indicators, and nitrogen assimilation. High salt concentrations significantly altered biofilm communities' composition, structure, and function, leading to an overall decrease in alpha diversity and a decrease in diatom and cyanobacterial biomass, while green algae remained unchanged. Chlorophyll a content increased in biofilm exposed to low salt concentration (1 g/L) and decreased at high salt concentrations while carotenoid significantly increased even at high salinity (10 g/L). Biofilm also showed an increase in carbohydrates and a decrease in protein content under high salinities (10 and 30 g/L). In addition, salt stress-induced ROS generation in the biofilm, with an increase in H2O2 content, caused oxidative damage and lipid peroxidation with an increase in MDA levels. To prevent this damage, elevated proline content was recorded, and additionally, the biofilm exhibited antioxidant defense mechanisms by rising activity of ROS-scavenger enzymes such as SOD, CAT, and POD. Our experimental results highlighted the salinity effect on algal biofilm as well as physiological and biochemical responses. This study could help predict the consequences of freshwater salinization on river biofilms and its potential impact at the ecosystem level.

Foliar treatment with MSB (menadione sodium bisulphite) to increase artemisinin content in Artemisia annua plants

Artemisinin is a sesquiterpene lactone endoperoxide, recognized for its application as a treatment for malaria. Besides, it has activity against several types of cancers, as well as anti-viral and anti-inflammatory properties. The chemical synthesis of artemisinin is quite complex and economically unfeasible. Hence, artemisinin is typically obtained from Artemisia annua plants in low quantities in relation to the biomass. A strategy to increase the biosynthesis of secondary metabolites would be the application of elicitors. In this work, the effect of treating A. annua plants with menadione sodium bisulphite (MSB) is studied. An initial dose-optimization was conducted by treating the plants with different MBS concentrations (0, 0.2, 0.8, 1, 2, 3 and 4 mM) and artemisinin was quantified 48 h after treatment. The highest artemisinin content (3.71 mg artemisinin g−1 DW) was obtained with 1 mM of MSB. Then, harvesting time was optimised (24, 48 and 72 h after treatment application) with 1 mM of MSB. The largest increase in artemisinin content was observed at 48 h with an increment of 62.37 % over the control. The treatment increased H2O2 content, as well as the activity of superoxide dismutase (SOD) and ascorbate peroxidase (APX). Besides, MSB up-regulated HMGR (the gene for 3-hydroxy-3-methylglutaryl-CoA reductase) and DXS (the gene for 1-deoxy-D-xylulose-5-phosphate synthase) 24 h after treatment. Both genes are involved in the MVA (mevalonate) and MEP (2C-methylerythritol 4-phosphate) pathways, respectively. These pathways represent the initiation of artemisinin biosynthesis. Thus, MSB application and the consequent up-regulation of early biosynthetic pathway genes along with the triggered oxidative stress may have been contributed to the observed increase in artemisinin production.