A quick, convenient and economical method for the reliable determination of methylglyoxal in millimolar concentrations: the N-acetyl-L-cysteine assay

Melatonin induced reversibility of vanadium toxicity in muskmelon by regulating antioxidant defense and glyoxalase systems

Agricultural lands with vanadium (V), pose a significant and widespread threat to crop production worldwide. The study was designed to explore the melatonin (ME) treatment in reducing the V-induced phytotoxicity in muskmelon. The muskmelon seedlings were grown hydroponically and subjected to V (40 mg L-1) stress and exogenously treated with ME (100 μmol L-1) to mitigate the V-induced toxicity. The results showed that V toxicity displayed a remarkably adverse effect on seedling growth and biomass, primarily by impeding root development, the photosynthesis system and the activities of antioxidants. Contrarily, the application of ME mitigated the V-induced growth damage and significantly improved root attributes, photosynthetic efficiency, leaf gas exchange parameters and mineral homeostasis by reducing V accumulation in leaves and roots. Additionally, a significant reduction in the accumulation of reactive oxygen species (ROS), malondialdehyde (MDA) along with a decrease in electrolyte leakage was observed in muskmelon seedlings treated with ME under V-stress. This reduction was attributed to the enhancement in the activities of antioxidants in leaves/roots such as ascorbate (AsA), superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), glutathione peroxidase (GPX), glutathione S-transferase (GST) as compared to the V stressed plants. Moreover, ME also upregulated the chlorophyll biosynthesis and antioxidants genes expression in muskmelon. Given these findings, ME treatment exhibited a significant improvement in growth attributes, photosynthesis efficiency and the activities of antioxidants (enzymatic and non-enzymatic) by regulating their expression of genes against V-stress with considerable reduction in oxidative damage.

Is Methylglyoxal a Potential Biomarker for the Warburg Effect Induced by the Lipopolysaccharide Neuroinflammation Model?

Methylglyoxal (MG) is considered a classical biomarker of diabetes mellitus and its comorbidities. However, a role for this compound in exacerbated immune responses, such as septicemia, is being increasingly observed and requires clarification, particularly in the context of neuroinflammatory responses. Herein, we used two different approaches (in vivo and acute hippocampal slice models) to investigate MG as a biomarker of neuroinflammation and the neuroimmunometabolic shift to glycolysis in lipopolysaccharide (LPS) inflammation models. Our data reinforce the hypothesis that LPS-induced neuroinflammation stimulates the cerebral innate immune response by increasing IL-1β, a classical pro-inflammatory cytokine, and the astrocyte reactive response, via elevating S100B secretion and GFAP levels. Acute neuroinflammation promotes an early neuroimmunometabolic shift to glycolysis by elevating glucose uptake, lactate release, PFK1, and PK activities. We observed high serum and cerebral MG levels, in association with a reduction in glyoxalase 1 detoxification activity, and a close correlation between serum and hippocampus MG levels with the systemic and neuroinflammatory responses to LPS. Findings strongly suggest a role for MG in immune responses.

Selenium and its nanoparticles modulate the metabolism of reactive oxygen species and morpho-physiology of wheat (Triticum aestivum L.) to combat oxidative stress under water deficit conditions

BACKGROUND

Wheat (Triticum aestivum L.) is one of the most important cereal crop species worldwide, but its growth and development are adversely influenced by drought stress. However, the application of trace elements is known to improve plant physiology under water-limited conditions. In this study, the effects of drought stress on wheat plants were investigated, with a focus on potential mitigation by foliar application of selenium nanoparticles (Se(np)) and sodium selenate (Na2SeO4). The experiment was conducted in a net house using a completely randomized design with four replications. The treatments involved three levels of drought stress (mild, moderate, and severe) started at 30 days after sowing (DAS), with foliar sprays of Se(np) and Se (both 25 µM) initiated at 27 DAS and repeated 4 times at 7-day intervals until 55 DAS.

RESULTS

Drought stress significantly reduced plant growth, whereas Se(np) and Se sprays enhanced it. Drought stress induced chlorophyll degradation, increased malondialdehyde and hydrogen peroxide levels, impaired membrane stability, and caused electrolyte leakage. Severe drought stress reduced the levels of antioxidants (e.g., proline, ascorbate, and glutathione by 4.18-fold, 80%, and 45%) and the activities of antioxidant enzymes (ascorbate peroxidase, dehydroascorbate reductase, and others). Conversely, treatment with Se(np) and Se restored these parameters, for example, 1.23-fold higher total chlorophyll content with Se(np) treatment, 26% higher APX activity with Se treatment, 15% lower electrolyte leakage with Se treatment in wheat plants under severe drought stress. This Se-associated enhancement facilitated rapid scavenging of reactive oxygen species and reduced methylglyoxal toxicity, thereby diminishing oxidative stress and positively affecting the morphophysiological and biochemical responses of the plants under drought.

CONCLUSIONS

Drought-stressed wheat plants exhibited reductions in physiological processes, including water uptake and photosynthetic activity. However, Se(np) and Se applied at 25 µM mitigated the detrimental effects of drought. The application of Se(np) was notably more effective than the application of Se in mitigating drought stress, indicating the potential of the application of Se(np) as a sustainable agricultural practice under water-limited conditions.

Harnessing plant growth-promoting rhizobacteria, Bacillus subtilis and B. aryabhattai to combat salt stress in rice: a study on the regulation of antioxidant defense, ion homeostasis, and photosynthetic parameters

Introduction

The ongoing global expansion of salt-affected land is a significant factor, limiting the growth and yield of crops, particularly rice (Oryza sativa L). This experiment explores the mitigation of salt-induced damage in rice (cv BRRI dhan100) following the application of plant growth-promoting rhizobacteria (PGPR).

Methods

Rice seedlings, at five- and six-weeks post-transplanting, were subjected to salt stress treatments using 50 and 100 mM NaCl at seven-day intervals. Bacterial cultures consisting of endophytic PGPR (Bacillus subtilis and B. aryabhattai) and an epiphytic PGPR (B. aryabhattai) were administered at three critical stages: transplantation of 42-day-old seedlings, vegetative stage at five weeks post-transplantation, and panicle initiation stage at seven weeks post-transplantation.

Results

Salt stress induced osmotic stress, ionic imbalances, and oxidative damage in rice plants, with consequent negative effects on growth, decrease in photosynthetic efficiency, and changes in hormonal regulation, along with increased methylglyoxal (MG) toxicity. PGPR treatment alleviated salinity effects by improving plant antioxidant defenses, restoring ionic equilibrium, enhancing water balance, increasing nutrient uptake, improving photosynthetic attributes, bolstering hormone synthesis, and enhancing MG detoxification.

Discussion

These findings highlight the potential of PGPR to bolster physiological and biochemical functionality in rice by serving as an effective buffer against salt stress-induced damage. B. subtilis showed the greatest benefits, while both the endophytic and epiphytic B. aryabhattai had commendable effects in mitigating salt stress-induced damage in rice plants.

Comprehensive multi-layered analyses of genotype-dependent proteo-metabolic networks reveal organellar crosstalk and biochemical pathways regulating aroma formation in rice

Molecular basis of rice aroma formation is sparsely known and developmental programs driving biochemical pathways towards aroma is in infancy. Here, discovery and targeted proteo-metabolome of non-aromatic and aromatic rice seeds across developmental stages identified a total of 442 aroma-responsive proteins (ARPs) and 824 aroma-responsive metabolites (ARMs) involved in metabolism, calcium and G-protein signaling. Biochemical examination revealed ARM/Ps were linked to 2-acetylpyrrolidine, γ-aminobutyrate, anthocyanin, tannins, flavonoids and related enzymes. Pairwise correlation and clustering showed positive correlation among ARM/Ps. Consistent with aroma-related QTLs, ARPs were mapped on chromosomes 3,4,5,8 and were mainly compartmentalized in cytoplasm and mitochondria. ARM/P-correlation network identified associations related to metabolism and signaling. Multiple reaction monitoring (MRM) confirmed role of catechins, quinic acid and quercetin in aroma formation. Pathway enrichment, multivariate analysis and qRT-PCR validated that calcium and G-protein signaling, aromatic/branched-chain aminoacid, 2-acetylpyrrolidine, oxylipin, melvonate and prenylpyrophosphate pathways, indole, phenylacetate, flavonoid, cinnamoic ester govern aroma formation in rice.

Potential of melatonin and Trichoderma harzianum inoculation in ameliorating salt toxicity in watermelon: Insights into antioxidant system, leaf ultrastructure, and gene regulation

Melatonin (MT) is an extensively studied biomolecule with dual functions, serving as an antioxidant and a signaling molecule. Trichoderma Harzianum (TH) is widely recognized for its effectiveness as a biocontrol agent against many plant pathogens. However, the interplay between seed priming and MT (150 μm) in response to NaCl (100 mM) and its interaction with TH have rarely been investigated. This study aimed to evaluate the potential of MT and TH, alone and in combination, to mitigate salt stress (SS) in watermelon plants. The findings of this study revealed a significant decline in the morphological, physiological, and biochemical indices of watermelon seedlings exposed to SS. However, MT and TH treatments reduced the negative impact of salt stress. The combined application of MT and TH exerted a remarkable positive effect by increasing the growth, photosynthetic and gas exchange parameters, chlorophyll fluorescence indices, and ion balance (decreasing Na+ and enhancing K+). MT and TH effectively alleviated oxidative injury by inhibiting hydrogen peroxide formation in saline and non-saline environments, as established by reduced lipid peroxidation and electrolyte leakage. Moreover, oxidative injury induced by SS on the cells was significantly mitigated by regulation of the antioxidant system, AsA-GSH-related enzymes, the glyoxalase system, augmentation of osmolytes, and activation of several genes involved in the defense system. Additionally, the reduction in oxidative damage was examined by chloroplast integrity via transmission electron microscopy (TEM). Overall, the results of this study provide a promising contribution of MT and TH in safeguarding the watermelon crop from oxidative damage induced by salt stress.

Biochar and silicon relegate the adversities of beryllium stress in pepper by modulating methylglyoxal detoxification and antioxidant defense mechanism

Industrial activities have escalated beryllium (Be) release in environment which negatively affect plant growth and human health. This investigation describes Be-induced stress in pepper and its palliation by application of pineapple fruit peel biochar (BC) and potassium silicate (Si). The treatment of Be reduced seedling length, biomass, and physiological attributes and enhanced electrolyte leakage, hydrogen peroxide (H2O2), superoxide (O2•-) level in pepper plants; however, these oxidative stress markers were reduced with combined treatment (Be + BC + Si). Application of BC and Si also lowered Be cumulation in roots and shoots of pepper. Under combined treatment, superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) activities exhibited significant enhancement 19, 7.6, 22.8, and 48%, respectively, in Be-stressed pepper. The Be + BC + Si increased peroxidase (POD), glutathione S-transferase (GPX), and glutathione peroxidase (GST) activities 121, 55, and 53%, respectively, as compared to Be-treated pepper. Methylglyoxal level was reduced in pepper with rise in glyoxalase I and II enzymes. Thus, combined application of SS and BC effectively protects pepper against oxidative stress induced by Be by increasing both antioxidant defense and glyoxalase systems. Hence, pineapple fruit peel biochar along with potassium silicate can be used for enhancing crop productivity under Be-contaminated soil.

Genome sequencing and protein modeling unraveled the 2AP biosynthesis in Bacillus cereus DB25

2-Acetyl-1-pyrroline (2AP) is an important and major flavor aroma compound responsible for the fragrance of basmati rice, cheese, wine, and several other food products. Biosynthesis of 2AP in aromatic rice and a few other plant species is associated with a recessive Betaine aldehyde dehydrogenase 2 (BADH2) gene. However, the literature is scant on the relationship between the functional BADH2 gene and 2AP biosynthesis in prokaryotic systems. Therefore, in the present study, we aimed to explore the functionality of the BADH2 gene for 2AP biosynthesis in 2AP synthesizing rice rhizobacterial isolate Bacillus cereus DB25 isolated from the rhizosphere of basmati rice (Oryza sativa L.). Full-length BcBADH2 sequence was obtained through whole genome sequencing (WGS) and further confirmed through traditional PCR and Sanger sequencing. Then the functionality of the BcBADH2 gene was evaluated in-silico through bioinformatics analysis and protein docking studies and further experimentally validated through enzyme assay. The sequencing and bioinformatics analysis results revealed a full-length 1485 bp BcBADH2 coding sequence without any deletion or premature stop codons. Full-length BcBADH2 was found to encode a fully functional protein of 54.08 kDa with pI of 5.22 and showed the presence of the conserved amino acids responsible for enzyme activity. The docking studies confirmed a good affinity between the protein and its substrate whereas the presence of BcBADH2 enzyme activity confirmed the functionality of BADH2 enzyme in B. cereus DB25. In conclusion, the findings of the present study suggest that B. cereus DB25 is able to synthesize 2AP despite a functional BADH2 gene and there may be a different molecular mechanism responsible for 2AP biosynthesis in bacterial systems, unlike that found in aromatic rice and other eukaryotic plant species.

Unlocking the potential of co-application of steel slag and biochar in mitigation of arsenic-induced oxidative stress by modulating antioxidant and glyoxalase system in Abelmoschus esculentus L

This study investigates our hypothesis that how effect of arsenic stress on okra (Abelmoschus esculentus L.) can be alleviated through the use of waste materials such as steel slag (SS) and corncob biochar (BC). Different growth variables, biochemical parameters, oxidative stress markers, enzymatic and non-enzymatic antioxidants and glyoxylase enzyme activities were assessed. When okra was exposed to As, there was a noticeable decrease in seedling length, biomass, relative water content, various biochemical attributes, however, electrolyte leakage and lipid peroxidation in okra were enhanced. The supplementation of SS and BC-either individually or in combination-improved the growth parameters and reduced oxidative stress markers. Application of SS and BC also lowered As accumulation in roots and shoots of okra mitigating adverse effects of As exposure. Additionally, the activities of antioxidant and glyoxalase enzyme increased when SS and BC were present, concurrently reducing methylglyoxal content. Arsenic-induced stress led to oxidative damage, an enhancement in both enzymatic and non-enzymatic antioxidants, induced the synthesis of thiol and phytochelatins in roots and shoots. These may play a vital function in alleviating oxidative stress induced by As. Superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase activities were significantly enhanced in As-treated plants. These enhancement were further amplified when SS and BC were amended to As-treated okra. Therefore, synergistic application of SS and BC effectively protects okra against oxidative stress induced by As by increasing both antioxidant defense and glyoxalase systems. Both SS, an industrial byproduct, and BC, generated from agricultural waste, are cost-effective, environmentally friendly, safe, and non-toxic materials which can be used for crop production in As contaminated soil.

Melatonin improves drought stress tolerance of pepper (Capsicum annuum) plants via upregulating nitrogen metabolism

While ameliorating effects of melatonin (MT) on abiotic stress tolerance in plants are widely reported, the mechanism that underlies this process remains elusive. This work investigated mechanisms by which MT improved drought tolerance in pepper (Capsicum annuum ) plants. A foliar spray of 0.1mM MT treatment was applied to plants grown at 80% and 40% of full field capacity for 3days. Drought stress caused a significant decrease in plant dry weight, relative water content, leaf water potential, PSII efficiency (F v /F m ratio), chlorophyll, soluble protein, leaf and root nitrogen content. Drought increased hydrogen peroxide, malondialdehyde (MDA), nitrate, ammonium, free amino acids, soluble sugars, proline and glycine betaine. Drought also increased peroxidase (POD), glutathione S-transferase (GST) and catalase (CAT) activities, electrolyte leakage (EL) and methylglyoxal (MG). MT pre-treatment reduced oxidative stress and improved nitrogen metabolism by activating various enzymes such as nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS), glutamate synthetase (GOGAT) and glutamine dehydrogenase (GDH) activities. It also activated enzymes related to the glyoxalase system (Gly I and Gly II) and decreased NO3 - , NH4 + and free amino acid content. Our study suggests a cost-effective and sustainable solution to improve crop productivity in water-limited conditions, by enhancing plant growth, photosynthesis and nitrogen content.

N-Acetyl-l-cysteine ameliorates gestational diabetes mellitus by inhibiting oxidative stress

Objective: Gestational diabetes mellitus (GDM) affects 7% of pregnant women worldwide. How to effectively treat GDM has always been a concern of people.Research methods: In this study, a diabetes model was established by drug-induced mice. Subsequently, the blood glucose levels and serum insulin changes of the mice after N-acetyl-l-cysteine (NAC) treatment were observed. At the same time, the effect of NAC on reproduction of GDM mice was recorded.Results of the study: Mice fed NAC showed significantly improved glucose tolerance and insulin sensitivity compared to Diabetic/Control. Total serum cholesterol, serum triglycerides, and serum low-density lipoprotein were significantly reduced, and atherosclerosis index was much lower than in control mice. In addition, Diabetic/Control mice had lower litter sizes and higher birth weights. NAC treatment significantly restored litter size and reduced birth weight in Diabetic/Control mice. It was found in WB assay that the NAC-fed group significantly increased nuclear Nrf2 and HO-1 expression levels.Conclusion: NAC can improve blood glucose tolerance in GDM mice; NAC effectively relieves the symptoms of hyperlipidemia caused by GDM; NAC enhances the expression of Nrf2/HO-1 in the liver, thereby restoring redox homeostasis. NAC can reduce gestational diabetes-related disease indicators by oral administration, and has a beneficial effect on the offspring of pregnant mice (reduces its diabetes disease indicators).

Glycation modulates superoxide dismutase 1 aggregation and toxicity in models of sporadic amyotrophic lateral sclerosis

Different SOD1 proteoforms are implicated## in both familial and sporadic cases of Amyotrophic Lateral Sclerosis (ALS), an aging-associated disease that affects motor neurons. SOD1 is crucial to neuronal metabolism and health, regulating the oxidative stress response and the shift between oxidative-fermentative metabolism, which is important for astrocyte-neuron metabolic cooperation. Neurons have a limited capacity to metabolize methylglyoxal (MGO), a potentially toxic side product of glycolysis. MGO is highly reactive and can readily posttranslationally modify proteins, in a reaction known as glycation, impacting their normal biology. Here, we aimed to investigate the effect of glycation on the aggregation and toxicity of human SOD1WT (hSOD1WT). Cells with deficiency in MGO metabolism showed increased levels of hSOD1WT inclusions, displaying also reduced hSOD1WT activity and viability. Strikingly, we also found that the presence of hSOD1WT in stress granules increased upon MGO treatment. The treatment of recombinant hSOD1WT with MGO resulted in the formation of SDS-stable oligomers, specially trimers, and thioflavin-T positive aggregates, which can promote cell toxicity and TDP-43 pathology. Together, our results suggest that glycation may play a still underappreciated role on hSOD1WT and TDP-43 pathologies in sporadic ALS, which could open novel perspectives for therapeutic intervention.

Evidence of polyamines mediated 2-acetyl-1-pyrroline biosynthesis in aromatic rice rhizospheric fungal species Aspergillus niger

Rhizosphere soil of aromatic rice inhabits different fungal species that produce many bioactive metabolites including 2-acetyl-1-pyrroline (2AP). The mechanism for the biosynthesis of 2AP in the fungal system is still elusive. Hence, the present study investigates the role of possible nitrogen (N) precursors such as some amino acids and polyamines as well as the enzymes involved in 2AP synthesis in the fungal species isolated from the rhizosphere of aromatic rice varieties. Three fungal isolates were found to synthesize 2AP (0.32-1.07 ppm) and maximum 2AP was synthesized by Aspergillus niger (1.07 ppm) isolated from rhizosphere of Dehradun Basmati (DB). To determine the N source for 2AP synthesis, various N sources such as proline, glutamate, ornithine putrescine, spermine, and spermidine were used in place of putrescine in the synthetic medium (Syn18). The results showed that maximum 2AP synthesis was found with putrescine (1.07 ppm) followed by spermidine (0.89 ppm) and spermine (0.84 ppm). Further, LC-QTOF-MS analysis revealed the mobilization of spermine and spermidine into the putrescine, indicating that putrescine is the key N source for 2AP synthesis. Moreover, higher enzyme activity of DAO, PAO, and ODC as well as higher content of methylglyoxal metabolite in the A. niger NFCCI 5060 as compared to A. niger NFCCI 4064 (control) suggests the prominent role of these enzymes in the synthesis of 2AP. In conclusion, this study showed evidence of the polyamines mediated 2AP biosynthesis in A. niger NFCCI 5060.

Bio-priming with a Novel Plant Growth-Promoting Acinetobacter indicus Strain Alleviates Arsenic-Fluoride Co-toxicity in Rice by Modulating the Physiome and Micronutrient Homeostasis

Sustainable remediation of arsenic-fluoride from rice fields through efficient bio-extraction is the need of the hour, since these toxicants severely challenge safe cultivation of rice and food biosafety. In the present study, we screened an arsenic-fluoride tolerant strain AB-ARC of Acinetobacter indicus from the soil of a severely polluted region of West Bengal, India, which was capable of efficiently removing extremely high doses of arsenate and fluoride from the media. The strain also behaved as a plant growth-promoting rhizobacterium, since it could produce indole-3-acetic acid and solubilize phosphate, zinc, and starch. Due to these properties of the identified strain, it was used for bio-priming the seeds of the arsenic-fluoride susceptible rice cultivar, Khitish for testing the efficacy of the AB-ARC strain to promote combined arsenic-fluoride tolerance in the rice genotype. Bio-priming with AB-ARC led to accelerated uptake of crucial elements like iron, copper, and nickel which behave as co-factors of physiological and antioxidative enzymes. Thus, the activation of superoxide dismutase, catalase, guaiacol peroxidase, glutathione peroxidase, and glutathione-S-transferase enabled detoxification of reactive oxygen species (ROS) and reduction of the oxidative injuries like malondialdehyde and methylglyoxal generation. Overall, due to ameliorated molecular damages and low uptake of the toxic xenobiotics, the plants were able to maintain improved growth vigor and photosynthesis, as evident from the elevated levels of Hill activity and chlorophyll content. Hence, bio-priming with the A. indicus AB-ARC strain may be advocated for sustainable rice cultivation in arsenic-fluoride co-polluted fields.

Exogenous Hydrogen Sulfide Supplementation Alleviates the Salinity-Stress-Mediated Growth Decline in Wheat (Triticum aestivum L.) by Modulating Tolerance Mechanisms

The impact of the exogenous supplementation of hydrogen sulfide (20 and 50 µM HS) on growth, enzyme activity, chlorophyll pigments, and tolerance mechanisms was studied in salinity-stressed (100 mM NaCl) wheat. Salinity significantly reduced height, fresh and dry weight, chlorophyll, and carotenoids. However, the supplementation of HS (at both concentrations) increased these attributes and also mitigated the decline to a considerable extent. The exogenous supplementation of HS reduced the accumulation of hydrogen peroxide (H2O2) and methylglyoxal (MG), thereby reducing lipid peroxidation and increasing the membrane stability index (MSI). Salinity stress increased H2O2, MG, and lipid peroxidation while reducing the MSI. The activity of nitrate reductase was reduced due to NaCl. However, the supplementation of HS alleviated the decline with obvious effects being seen due to 50 µM HS. The activity of antioxidant enzymes (superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase) was assayed and the content of reduced glutathione (GSH) increased due to salt stress and the supplementation of HS further enhanced their activity. A decline in ascorbic acid due to salinity stress was alleviated due to HS treatment. HS treatment increased the endogenous concentration of HS and nitric oxide (NO) under normal conditions. However, under salinity stress, HS supplementation resulted in a reduction in HS and NO as compared to NaCl-treated plants. In addition, proline and glycine betaine increased due to HS supplementation. HS treatment reduced sodium levels, while the increase in potassium justified the beneficial role of applied HS in improving salt tolerance in wheat.

Titanium dioxide nanoparticles require K+ and hydrogen sulfide to regulate nitrogen and carbohydrate metabolism during adaptive response to drought and nickel stress in cucumber

Crop plants face severe yield losses worldwide owing to their exposure to multiple abiotic stresses. The study described here, was conducted to comprehend the response of cucumber seedlings to drought (induced by 15% w/v polyethylene glycol 8000; PEG) and nickel (Ni) stress in presence or absence of titanium dioxide nanoparticle (nTiO2). In addition, it was also investigated how nitrogen (N) and carbohydrate metabolism, as well as the defense system, are affected by endogenous potassium (K+) and hydrogen sulfide (H2S). Cucumber seedlings were subjected to Ni stress and drought, which led to oxidative stress and triggered the defense system. Under the stress, N and carbohydrate metabolism were differentially affected. Supplementation of the stressed seedlings with nTiO2 (15 mg L-1) enhanced the activity of antioxidant enzymes, ascorbate-glutathione (AsA-GSH) system and elevated N and carbohydrates metabolism. Application of nTiO2 also enhanced the accumulation of phytochelatins and activity of the enzymes of glyoxalase system that provided additional protection against the metal and toxic methylglyoxal. Osmotic stress brought on by PEG and Ni, was countered by the increase of proline and carbohydrates levels, which helped the seedlings keep their optimal level of hydration. Application nTiO2 improved the biosynthesis of H2S and K+ retention through regulating Cys biosynthesis and H+-ATPase activity, respectively. Observed outcomes lead to the conclusion that nTiO2 maintains redox homeostasis, and normal functioning of N and carbohydrates metabolism that resulted in the protection of cucumber seedlings against drought and Ni stress. Use of 20 mM tetraethylammonium chloride (K+- channel blocker), 500 μM sodium orthovanadate (PM H+-ATPase inhibitor), and 1 mM hypotaurine (H2S scavenger) demonstrate that endogenous K+ and H2S were crucial for the nTiO2-induced modulation of plants' adaptive responses to the imposed stress.

Deciphering the biochemical regulation of metabolic pathways in abating stress-induced damages during co-exposure of arsenic and fluoride in a non-aromatic and an aromatic rice variety

The aim of the current work was to decipher the systemic damage and biochemical defense machinery due to combined arsenic (5 mg L-1 Na3AsO4) and fluoride (50 mg L-1 NaF) stress in two rice cultivars viz., IR-64 (non-aromatic) and Gobindobhog (aromatic), grown for 14 days, under 16/8 h light/dark photoperiodic cycle at 32 °C. Higher accumulation of arsenic and fluoride in Gobindobhog generated higher levels of H2O2 that caused higher electrolyte leakage, along with malondialdehyde and methylglyoxal formation. Higher oxidative damages severely compromised seed germination and led to chlorophyll loss, inhibition of root and shoot growth and fresh and dry weight of the seedlings. On the contrary, oxidative damage was less pronounced in IR-64, as compared to that of Gobindobhog, which can be attributed to higher accumulation of protective metabolites, i.e., osmolytes and antioxidants. Higher levels of osmolytes (proline, glycine betaine and amino acids) in IR-64 helped in maintaining the osmotic balance of the cells and the integrity of the cell membrane. Additionally, up regulated activity of enzymatic antioxidants (catalase, superoxide dismutase, ascorbate peroxidase, glutathione peroxidase and glutathione S-transferase) along with elevated levels of non-enzymatic antioxidants (flavonoids, phenolics, xanthophylls and carotenoids) played a pivotal role in controlling oxidative damages and strengthening the defense machinery in IR-64, as compared to that of Gobindobhog where lesser enhancement in the level of the above mentioned protective metabolites was noted. The present work illustrated differential phytotoxicity in rice seedlings and elucidated the yet uncharacterized biohazard associated with arsenic and fluoride co-contamination, with better adaptive features of IR-64, compared to Gobindobhog, which appeared as the sensitive variety.

Methyl jasmonate influences ethylene formation, defense systems, nutrient homeostasis and carbohydrate metabolism to alleviate arsenic-induced stress in rice (Oryza sativa)

The plant growth regulator, jasmonic acid (JA) has emerged as important molecule and involved in key processes of plants. In this study, we investigated the role of methyl jasmonate (MeJA) in achieving tolerance mechanisms against arsenic (As) stress in rice (Oryza sativa). Arsenic toxicity is a major global concern that significantly deteriorate rice production. The application of MeJA (20 μM) and ethylene (150 μL L-1) both individually and/or in combination were found significant in protecting against As-induced toxicity in rice, and significantly improved defense systems. The study shown that the positive influence of MeJA in promoting carbohydrate metabolism, photosynthesis and growth under As stress were the result of its interplay with ethylene biosynthesis and reduced oxidative stress-mediated cellular injuries and cell deaths. Interestingly, the use of JA biosynthesis inhibitor, neomycin (Neo) and ethylene biosynthesis inhibitor, aminoethoxyvinylglycine (AVG) overturned the effects of MeJA and ethylene on plant growth under As stress. From the pooled data, it may also be concluded that Neo treatment to MeJA- treated rice plants restricted JA-mediated responses, implying that application of MeJA modulated ethylene- dependent pathways in response to As stress. Thus, the action of MeJA in As tolerance is found to be mediated by ethylene. The study will shed light on the mechanisms that could be used to ensure the sustainability of rice plants under As stress.

Unravelling the molecular and biochemical responses in cotton plants to biochar and biofertilizer amendments for Pb toxicity mitigation

Over the past few years, there has been a rising interest in employing biochar (BC) and biofertilizers (BF) as a means of restoring soils that have been polluted by heavy metals. The primary objective of this study was to examine how the application of BC and BF affects the ability of cotton plants to withstand Pb toxicity at varying concentrations (0, 500, and 1000 mg/kg soil). The findings revealed that exposure to Pb stress, particularly at the 1000 mg/kg level, led to a decline in the growth and biomass of cotton plants. Pb toxicity triggered oxidative damage, impaired the photosynthetic apparatus, and diminished the levels of photosynthetic pigments. By increasing the expression of Rubisco-S, Rubisco-L, P5CR, and PRP5 genes and regulating proline metabolism, BC and BF increased the levels of proline and photosynthetic pigments and protected the photosynthetic apparatus. The application of BC and BF resulted in an upregulation of genes such as CuZnSOD, FeSOD, and APX1, as well as an increase in the activity of the glyoxalase system and antioxidant enzymes. These changes enhanced the antioxidant capacity of the plants and provided protection to membrane lipids from oxidative stress caused by Pb. The inclusion of BC and BF offered protection to photosynthesis and other essential intracellular processes in leaves by minimizing the transfer of Pb to leaves and promoting the accumulation of thiol compounds. This protective effect helped mitigate the negative impact of the toxic metal Pb on leaf function. By improving plant tolerance, reducing metal transfer, strengthening the antioxidant defense system, and enhancing the level of protective substances, these amendments show promise as valuable tools in tackling heavy metal pollution.

Melatonin and strigolactone mitigate chromium toxicity through modulation of ascorbate-glutathione pathway and gene expression in tomato

Chromium (Cr) is considered one of the most hazardous metal contaminant reducing crop production and putting human health at risk. Phytohormones are known to regulate chromium stress, however, the function of melatonin and strigolactones in Chromium stress tolerance in tomato is rarely investigated. Here we investigated the potential role of melatonin (ML) and strigolactone (SL) on mitigating Chromium toxicity in tomato. With exposure to 300 μM Cr stress a remarkable decline in growth (63.01%), biomass yield (50.25)%, Pigment content (24.32%), photosynthesis, gas exchange and Physico-biochemical attributes of tomato was observed. Cr treatment also resulted in oxidative stress closely associated with higher H2O2 generation (215.66%), Lipid peroxidation (50.29%), electrolyte leakage (440.01%) and accumulation of osmolytes like proline and glycine betine. Moreover, Cr toxicity up-regulated the transcriptional expression profiles of antioxidant, stress related and metal transporter genes and down-regulated the genes related to photosynthesis. The application of ML and SL alleviated the Cr induced phytotoxic effects on photosynthetic pigments, gas exchange parameters and restored growth of tomato plants. ML and SL supplementation induced plant defense system via enhanced regulation of antioxidant enzymes, ascorbate and glutathione pool and transcriptional regulation of several genes. The coordinated regulation of antioxidant and glyoxalase systems expressively suppressed the oxidative stress. Hence, ML and SL application might be considered as an effective approach for minimizing Cr uptake and its detrimental effects in tomato plants grown in contaminated soils. The study may also provide new insights into the role of transcriptional regulation in the protection against heavy metal toxicity.

Combined effect of trehalose and spermidine to alleviate zinc toxicity in Vigna radiata

Zinc toxicity is affecting the growth and yield of major crops plants throughout globe by reducing key metabolic processes. In this backdrop, experiments were conducted to evaluate the influence of exogenous supplementation of trehalose (500 µM Treh) and spermidine (500 µM Spd) in alleviating the damaging effects of zinc toxicity (100 µM ZnSO4) in Vigna radiata. Growth, chlorophyll and photosynthesis were reduced due to Zn toxicity; however, exogenous supplementation of trehalose and spermidine not only increased the parameters but also alleviated the decline to considerable levels. Toxicity of zinc increased H2O2, lipid peroxidation and electrolyte leakage by 100.43%, 84.53% and 134.64%, respectively, and application of trehalose and spermidine a reduction of 29.32%, 39.09% and 44.91%, respectively, over the zinc-treated plants. Application of trehalose and spermidine increased the activity of nitrate reductase and the content of nitrogen concomitant with alleviation of the decline caused due to zinc toxicity. The activity of antioxidant system enzymes superoxide dismutase, catalase and the enzymes of ascorbate-glutathione cycle was significantly enhanced due to trehalose and spermidine application. Proline, glycine betaine and activity of γ-glutamyl kinase increased maximally by 281.84%, 126.21% and 181.08%, respectively, in plants treated with zinc + trehalose + spermidine over control. Significant enhancement in the content of total phenols and flavonoids was observed due to the treatment of trehalose and spermidine individually as well as combinedly. Application of trehalose and spermidine reduced the content of methylglyoxal by up-regulating the activity of glyoxylase cycle enzymes. In addition under zinc toxicity conditions, the content of zinc declined in trehalose- and spermidine-treated plants.

Arbuscular mycorrhiza differentially adjusts central carbon metabolism in two contrasting genotypes of Vigna radiata (L.) Wilczek in response to salt stress

The study aimed at investigating Arbuscular Mycorrhiza (AM) mediated metabolic changes in two genotypes of mungbean (Vigna radiata) differing in their salt tolerance in presence of salt stress (100 mM NaCl). Colonisation by Claroideoglomus etunicatum resulted in higher growth, photosynthetic efficiency, total protein content, and lower levels of stress markers, indicating alleviation of stress in mungbean plants. AM differentially upregulated the components of Tricarboxylic acid (TCA) cycle in salt tolerant (ST) and salt sensitive (SS) genotypes that could be correlated to AM-mediated moderation in nutrient uptake. Under salt stress, while maximum increase in the activity of α-ketoglutarate dehydrogenase (65%) was observed in mycorrhizal (M)-ST; the increase in isocitrate dehydrogenase (79%) and fumarase (133%) activities was maximum in M-SS plants over their non-mycorrhizal (NM) counterparts. Apart from TCA, AM also affected gamma-aminobutyric acid (GABA) and glyoxylate pathways. Activities of enzymes implicated in GABA shunt increased in both the genotypes under stress resulting in increase in GABA concentration (46%). Notably, glyoxylate pathway was induced by AM in SS only, wherein M-SS exhibited significantly higher isocitrate lyase (49%) and malate synthase (104%) activities, reflected in higher malic acid concentration (84%), than NM under stress. The results suggest that AM moderates the central carbon metabolism and strategizes towards boosting the formation of stress-alleviating metabolites such as GABA and malic acid, especially in SS, bypassing the steps catalysed by salt-sensitive enzymes in TCA cycle. The study, therefore, advances the understanding on mechanisms by which AM ameliorates salt stress.

Nitric Oxide and Strigolactone Alleviate Mercury-Induced Oxidative Stress in Lens culinaris L. by Modulating Glyoxalase and Antioxidant Defense System

Developmental activities have escalated mercury (Hg) content in the environment and caused food security problems. The present investigation describes mercury-incited stress in Lens culinaris (lentil) and its mitigation by supplementation of sodium nitroprusside (SNP) and strigolactone (GR24). Lentil exposure to Hg decreased root and shoot length, relative water content and biochemical variables. Exogenous application of SNP and GR24 alone or in combination enhanced all of the aforementioned growth parameters. Hg treatment increased electrolyte leakage and malondialdehyde content, but this significantly decreased with combined application (Hg + SNP + GR24). SNP and GR24 boosted mineral uptake and reduced Hg accumulation, thus minimizing the adverse impacts of Hg. An increase in mineral accretion was recorded in lentil roots and shoots in the presence of SNP and GR24, which might support the growth of lentil plants under Hg stress. Hg accumulation was decreased in lentil roots and shoots by supplementation of SNP and GR24. The methylglyoxal level was reduced in lentil plants with increase in glyoxalase enzymes. Antioxidant and glyoxylase enzyme activities were increased by the presence of SNP and GR24. Therefore, synergistic application of nitric oxide and strigolactone protected lentil plants against Hg-incited oxidative pressure by boosting antioxidant defense and the glyoxalase system, which assisted in biochemical processes regulation.

Alleviation of arsenic toxicity in pepper plants by aminolevulinic acid and heme through modulating its sequestration and distribution within cell organelles

Aminolevulinic acid (ALA) is essential for chlorophyll and heme synthesis. However, whether heme interacts with ALA to elicit antioxidants in arsenic (As)-exposed plants is still unknown. ALA was applied daily to pepper plants for 3 days prior to beginning As stress (As-S). Then, As-S was initiated for 14 days by employing sodium hydrogen arsenate heptahydrate (0.1 mM AsV). Arsenic treatment decreased photosynthetic pigments (chl a by 38% and chl b by 28%), biomass by 24%, and heme by 47% content, but it elevated contents of malondialdehyde (MDA) by 3.3-fold, hydrogen peroxide (H₂O₂) by 2.3-fold, glutathione (GSH), methylglyoxal (MG), and phytochelatins (PCs) and electrolyte leakage (EL) by 2.3-fold along with enhanced subcellular As concentration in the pepper plant's roots and leaves. The supplementation of ALA to the As-S-pepper seedlings enhanced the amount of chlorophyll, heme content, and antioxidant enzyme activity as well as plant growth, while it reduced the levels of H₂O₂, MDA, and EL. ALA boosted GSH and phytochelates (PCs) in the As-S-seedlings by controlling As sequestration and rendering it harmless. The addition of ALA enhanced the amount of As that accumulated in the root vacuoles and reduced the poisonousness of the soluble As in the vacuoles. The ALA treatment facilitated the deposition and fixation of As in the vacuoles and cell walls, thereby reducing the transport of As to other cell organelles. This mechanism may have contributed to the observed decrease in As accumulation in the leaves. The administration of 0.5 mM hemin (H) (a source of heme) significantly enhanced ALA-induced arsenic stress tolerance. Hemopexin (Hx, 0.4 μg L^-1), a heme scavenger, was treated with the As-S plants along with ALA and ALA + H to observe if heme was a factor in ALA's increased As-S tolerance. Heme synthesis/accumulation in the pepper plants was reduced by Hx, which counteracted the positive effects of ALA. Supplementation of H along with ALA + Hx reversed the negative effects of Hx, demonstrating that heme is required for ALA-induced seedling As-S tolerance.

Gibberellic acid mitigates nickel stress in soybean by cell wall fixation and regulating oxidative stress metabolism and glyoxalase system

It is broadly known that excessive concentration of nickel (Ni) causes venomous effects on plant health as well as food security. The underlying gibberellic acid (GA) mechanism to overcome Ni-induced stress is still unclear. Our outcomes represented the potential role of gibberellic acid (GA) to boost the soybean stress tolerance mechanism against Ni toxicity. GA elevated the seed germination, plant growth, biomass indices, and photosynthetic machinery as well as relative water contents under Ni-induced stress in soybean. We found that the GA lowered the Ni uptake, and distribution in the soybean plants, as well as GA, can decrease the Ni fixation in the root cell wall by lowering the hemicelluloses content. However, it reduces the MDA level, over-generation of ROS, electrolyte leakage, and methylglyoxal contents by up-surging the level of antioxidant enzyme, and glyoxalase I and glyoxalase II activities. Furthermore, GA regulates the antioxidant-related (CAT, SOD, APX, and GSH) and phytochelatins (PCs) genes expression to sequester the excessive Ni to the vacuoles and efflux the Ni outer the cell. Hence, less Ni was translocated toward shoots. Overall, GA augmented cell wall Ni elimination, and the antioxidant defense mechanism possibly upgraded the soybean tolerance against Ni stress.

Nicosulfuron stress on the glyoxalase system and endogenous hormone content in sweet maize seedlings

To reduce the harmful effects of nicosulfuron on sweet corn, the physiological regulation mechanism of sweet corn detoxification was studied. This study analyzed the effects of nicosulfuron stress on the glyoxalase system, hormone content, and key gene expression of nicosulfuron-tolerant "HK301" and nicosulfuron-sensitive "HK320" sweet corn seedling sister lines. After spraying nicosulfuron, the methylglyoxal (MG) content in HK301 increased first and then decreased. Glyoxalase I (GlyI) and glyoxalase II (GlyII) activities, non-enzymatic glutathione (GSH), and the glutathione redox state glutathione/(glutathione + glutathione disulfide) (GSH/(GSH + GSSG)) showed a similar trend as the MG content. Abscisic acid (ABA), gibberellin (GA), and zeatin nucleoside (ZR) also increased first and then decreased, whereas the auxin (IAA) increased continuously. In HK301, all indices after spraying nicosulfuron were significantly greater than those of the control. In HK320, MG accumulation continued to increase after nicosulfuron spraying and GlyI and GlyII activities, and GSH first increased and then decreased after 1 day of stress. The indicators above were significantly greater than the control. The GSH/(GSH + GSSG) ratio showed a decreasing trend and was significantly smaller than the control. Furthermore, ABA and IAA continued to increase, and the GA and ZR first increased and then decreased. Compared with HK320, HK301 significantly upregulated the transcription levels of GlyI and GlyII genes in roots, stems, and leaves. Comprehensive analysis showed that sweet maize seedlings improved their herbicide resistance by changing the glyoxalase system and regulating endogenous hormones. The results provide a theoretical basis for further understanding the response mechanism of the glyoxalase system and the regulation characteristics of endogenous hormones in maize under nicosulfuron stress.

Sodium nitroprusside ameliorates lead toxicity in rice (Oryza sativa L.) by modulating the antioxidant scavenging system, nitrogen metabolism, lead sequestration mechanism, and proline metabolism

As a toxic anthropogenic pollutant, lead (Pb) can be harmful to both plants and animals. Here, the effects of the application of nitric oxide (NO) donor, sodium nitroprusside (SNP, 0, 50, and 100 μM), on the morphological, biochemical, and molecular responses of rice plants under Pb (0, 150, and 300 μM) toxicity in hydroponic conditions were investigated. Pb stress decreased biomass, photosynthetic pigments, Fv/Fm value, and nitrogen (N) and increased the accumulation of hydrogen peroxide (H₂O₂), methylglyoxal (MG), malondialdehyde (MDA), and electrolyte leakage (EL) in rice seedlings. However, by improving the metabolism of chlorophyll and proline, SNP increased the content of chlorophyll and proline, restored the performance of the photosynthetic apparatus, and stimulated the growth of Pb-stressed rice seedlings. SNP by reducing the expression of HMA2 and increasing the expression of HMA3 and HMA4 caused the immobilization of Pb in the roots and reduced its transfer to the leaves. Adding SNP increased the activity of antioxidant enzymes and glyoxalase cycle and decreased H₂O₂, MG, MDA, and EL in the leaves of Pb-stressed rice seedlings. By upregulating the expression of genes GSH1, PCS, and ABCC1, SNP increased the accumulation of GSH and PCs in the roots and leaves and increased the plant's tolerance to Pb stress. By modulating the activity of enzymes involved in N metabolism, SNP increased the concentration of N and nitrate and decreased the concentration of ammonium in the leaves of Pb-stressed seedlings. Our study provides evidence that NO may become a promising tool for increasing the tolerance of rice plants to Pb toxicity.

Nitric oxide and spermidine alleviate arsenic-incited oxidative damage in Cicer arietinum by modulating glyoxalase and antioxidant defense system

Anthropogenic activities such as mining, fossil fuel combustion, fertilisers and pesticides utilisation in agriculture, metallurgic processes and disposal of industrial wastes have contributed an exponential rise in arsenic content in environment. The present paper deals with arsenate (AsV) incited stress in chickpea (Cicer arietinum L.) plants and its alleviation through the application of nitric oxide (NO) and spermidine (SPD). The exposure of C. arietinum to AsV reduced seedling length, biomass, relative water content and biochemical constituents. All the above-mentioned parameters were escalated when sodium nitroprusside (SNP) or SPD were utilised alone or in combination with AsV. The electrolyte leakage and malondialdehyde content were increased in chickpea treated with AsV, but reduced in combine treatment (As+SNP+SPD). In chickpea seedlings, 89.4, 248.4 and 333.3% stimulation were recorded in sugar, proline and glycine betaine contents, respectively, with As+SNP+SPD treatment in comparison to control. SNP and SPD modulated function of glyoxalase enzymes by which methylglyoxal (MG) was significantly detoxified in C. arietinum . Maximum reduction 45.2% was observed in MG content in SNP+SPD treatment over AsV stress. Hence, synergistic application of NO and SPD protected chickpea plants against AsV-generated stress by strengthening the antioxidant defence and glyoxalase system, which helped in regulation of biochemical pathways.

Sesquiterpenoid-rich Java Ginger rhizome extract prompts autophagic cell death in cervical cancer cell SiHa mainly by modulating cellular redox homeostasis

Java Ginger or Curcuma zanthorrhiza Roxb. has long gained focus among tribal people of Java, for its medicinal properties mainly against gynaecological challenges. The present study aims to identify the most potent phytocompound present in the extract and determine primary mode of action accountable for cytotoxic activity of Curcuma zanthorrhiza rhizome extract against HPV16-positive SiHa cervical cancer cells. The phytochemically-rich extract of rhizome (CZM) was capable to inhibit proliferation of target cells in a dose-dependent manner with an IC50 of 150 μg/ml. Dysregulation of intercellular antioxidant defence system resulted to surges in ROS and RNS level, increased calcium concentration and compromised mitochondrial membrane potential. Nucleus got affected, cell cycle dynamics got impaired while clonogenicity and migration ability diminished. Expression of viral oncogenes E7 and E6 decreased significantly. Accumulation of toxic cell metabolite and decrease in level of essential ones continued. Finally, alteration in PI3K/AKT/mTOR signalling route was followed by onset of autophagic cell death concomitant with the upregulated expression of Beclin1, Atg5-12 and LC3II. Curcumin and a novel crystal as well as few phyto-fractions were isolated by column chromatography. Of these, curcumin was found to be most potent in inducing cytotoxicity in SiHa while two other fractions also showed significant activity. Thus, CZM acted against SiHa cells by inducing autophagy that commences in compliance to the changes in PI3K/AKT/mTOR pathway mainly in response to oxidative stress. To the best of our knowledge this is the first report of Curcuma zanthorrhiza Roxb. inducing autophagy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-022-03415-9.

Deficiency of Parkinson's Related Protein DJ-1 Alters Cdk5 Signalling and Induces Neuronal Death by Aberrant Cell Cycle Re-entry

DJ-1 is a multifunctional protein involved in Parkinson disease (PD) that can act as antioxidant, molecular chaperone, protease, glyoxalase, and transcriptional regulator. However, the exact mechanism by which DJ-1 dysfunction contributes to development of Parkinson's disease remains elusive. Here, using a comparative proteomic analysis between wild-type cortical neurons and neurons lacking DJ-1 (data available via ProteomeXchange, identifier PXD029351), we show that this protein is involved in cell cycle checkpoints disruption. We detect increased amount of p-tau and α-synuclein proteins, altered phosphoinositide-3-kinase/protein kinase B (PI3K/AKT) and mitogen-activated protein kinase (MAPK) signalling pathways, and deregulation of cyclin-dependent kinase 5 (Cdk5). Cdk5 is normally involved in dendritic growth, axon formation, and the establishment of synapses, but can also contribute to cell cycle progression in pathological conditions. In addition, we observed a decrease in proteasomal activity, probably due to tau phosphorylation that can also lead to activation of mitogenic signalling pathways. Taken together, our findings indicate, for the first time, that aborted cell cycle re-entry could be at the onset of DJ-1-associated PD. Therefore, new approaches targeting cell cycle re-entry can be envisaged to improve current therapeutic strategies.

Wheat variety carrying 2NvS chromosomal segment provides yield advantage through lowering terminal heat-induced oxidative stress

A 2N^vS chromosomal segment carrying bread wheat variety, BARI Gom 33 ('BG33'), showed tolerance to terminal heat stress and higher yield over a heat-tolerant non-2N^vS BARI Gom 26 ('BG26') and a heat-susceptible Pavon 76 ('Pavon'). This study aimed to ascertain the potential of the 2N^vS 'BG33' in terminal heat-induced oxidative stress tolerance compared to non-2N^vS 'BG26' and heat-susceptible 'Pavon' under two heat regimes at the reproductive stages viz. control (optimum sowing time) and heat stress (late sowing). We found that both 'BG26' and 'BG33' showed significantly higher tolerance to oxidative stress by limiting the generation of reactive oxygen species (ROS), methylglyoxal under heat stress. During terminal heat stress, both 'BG33' and 'BG26' exhibited greater cellular homeostasis than heat-susceptible 'Pavon', which was maintained by the increased accumulation of osmolytes, nonenzymatic antioxidants, and enzymes associated with ROS scavenging, ascorbate-glutathione cycle, and glyoxalase system. Lesser cellular damage in 'BG26' and 'BG33' was eventually imitated in a smaller reduction in grain yield (15 and 12%, respectively) than in 'Pavon', which had a 33% reduction owing to heat stress. Collectively, our findings revealed that the chromosomal segment 2N^vS provides yield advantage to 'BG33' under terminal heat stress by lowering oxidative damage. As 2N^vS translocation contains multiple nucleotide-binding domain leucine-rich repeat containing, cytochrome P450, and other gene families associated with plant stress tolerance, further studies are warranted to dissect the underlying molecular mechanisms associated with higher heat stress tolerance of 2N^vS carrying 'BG33'.

Nitric oxide and hydrogen sulfide work together to improve tolerance to salinity stress in wheat plants by upraising the AsA-GSH cycle

The participation of nitric oxide (NO) in wheat plant tolerance to salinity stress (SS) brought about by hydrogen sulphide (H₂S) via modifying the ascorbate-glutathione (AsA-GSH) cycle was studied. The SS-plants received either 0.2 mM sodium hydrosulfide (NaHS; H₂S donor), or NaHS plus 0.1 mM sodium nitroprusside (SNP; a NO donor) through the nutrient solution. Salinity stress decreased plant growth, leaf water status, leaf K⁺, and glyoxalase II (gly II), while it elevated proline content, leaf Na⁺ content, oxidative stress, methylglyoxal (MG), glyoxalase I (gly I), the superoxide dismutase, catalase and peroxidase activities, contents of endogenous NO and H₂S. The NaHS supplementation elevated plant development, decreased leaf Na⁺ content and oxidative stress, and altered leaf water status, leaf K⁺ and involved enzymes in AsA-GSH, H₂S and NO levels. The SNP supplementation boosted the positive impact of NaHS on these traits in the SS-plants. Moreover, 0.1 mM cPTIO, scavenger of NO, countered the beneficial effect of NaHS by lowering NO levels. SNP and NaHS + cPTIO together restored the beneficial effects of NaHS by increasing NO content, implying that NO may have been a major factor in SS tolerance in wheat plants induced by H₂S via activating enzymes connected to the AsA-GSH cycle.

Surface functionalization and size of polystyrene microplastics concomitantly regulate growth, photosynthesis and anti-oxidant status of Cicer arietinum L

Microplastics are a recent entrant in the list of environmental pollutants, exhibiting great diversity owing to different sizes, surface charges, and morphologies. The present study explores the impact of varied size, surface functionalization, and concentration of polystyrene microplastics (PS MP) on plants. For this study, Cicer seedlings were exposed to two different sizes of PS (1 μm and 12 μm) with three different surface functionalization (plain, carboxylated, and aminated) and at three distinct concentrations (10, 50, and 100 mg/L). The growth and photosynthetic parameters (like pigment content, Hill activity, etc.) along with oxidative stress marker (ROS) and anti-oxidant enzyme activities (like Superoxide dismutase, Catalase, and Peroxidase) were assessed. The results incline towards the idea that with increasing concentration of PS, there was a decline in the growth of the seedlings. There was also a dose-dependent increase in oxidative stress due to the suppression of the action of antioxidant enzymes. The effect was more prominent for 12 μm PS, perhaps due to its larger size and adherence to roots resulting in mechanical damage as deduced from MDA levels in the seedlings. Besides, MP with negative surface charge was comparatively less toxic than uncharged or positively charged PS of 1 μm. Overall, it can be concluded that the impact of MP on plants does not rely on individual characteristics of the particles alone, rather it is a concerted result of various determinants like size, charge, and concentration.

Extensive cross-talk among stress-regulated protective metabolites, biogenic-amines and phytohormone-signalling, co-ordinated by dopamine-mediated seed-priming, governs tolerance against fluoride stress in rice

Seed priming with dopamine reduced fluoride bioaccumulation, induced endogenous dopamine level, thereby orchestrating phytohormone homeostasis and biogenic amine metabolism, and modulating osmolyte and antioxidant machinery to enhance fluoride tolerance in rice. The aim of this study was to decipher the efficacy of seed priming with dopamine in curtailing the adverse impacts of fluoride toxicity in rice seedlings. Fluoride-stressed seedlings exhibited severe growth retardation, high fluoride bioaccumulation, electrolyte leakage and marked cellular injuries. Dopamine priming stimulated the overall physiological growth parameters during stress, via reduced formation of H₂O₂, malondialdehyde and methylglyoxal, due to lesser fluoride-accumulation. Fluoride stress-induced endogenous dopamine level was further induced upon dopamine priming, marked by the up regulated DOPA decarboxylase expression. Additionally, dopamine treatment led to escalated activity of catalase, superoxide dismutase and glutathione peroxidase in the stressed seedlings, concomitant with altered CAT, SOD and GPX expression. The higher accumulation of protective osmolytes (proline and total amino acids) and non-enzymatic antioxidants (phenolics, flavonoids, anthocyanins, glutathione and carotenoids), upon dopamine priming, during fluoride stress, could be linked with the altered expression pattern of the respective genes. Dopamine promoted active utilization of the biogenic amine (polyamines and ϒ-amino butyric acid) pools for toxicity mitigation, correlated with the modulation of the concerned enzyme activity and gene expression. Dopamine stimulated the accumulation of phytohormones like gibberellin and salicylic acid, via inducing the biosynthetic genes like gibberellin-3-oxidase (GA3ox) and isochorismate synthase (ICS), respectively, while depreciating the abscisic acid and melatonin level during fluoride stress. To our knowledge, this is the first documented report for the remedial role of dopamine priming against fluoride stress in any plant species. This study will open new arenas in sustainable agriculture for the exploitation of this pulsating biomolecule against fluoride stress.

The involvement of hydrogen sulphide in melatonin-induced tolerance to arsenic toxicity in pepper (Capsicum annuum L.) plants by regulating sequestration and subcellular distribution of arsenic, and antioxidant defense system

Melatonin (MT) and hydrogen sulphide (H₂S) are recognised as vital biomolecules actively taking part in plant defence systems as free radical scavengers and antioxidants against a myriad of biotic and abiotic stressors. However, it has been yet unknown in plants subjected to arsenic (As) toxicity whether or not H₂S interacts with MT to regulate endogenous antioxidant defence system. Prior to beginning As stress (As-S) treatments, MT (0.10 mM) was applied externally to plants daily for three days. AsS was then started for two weeks with As(V) (0.1 mM as Na₂HAsO₄·7H₂O). The treatment of As reduced plant biomass (24.4%) and chlorophyll a (51.7%), chlorophyll b (25.9%), while it increased subcellular As in roots and leaves, levels of glutathione (GSH), hydrogen peroxide (H₂O₂), malondialdehyde (MDA), methylglyoxal (MG), H₂S and phytochelatins (PCs) in pepper plants. In As-stressed pepper plants, the application of MT increased plant biomass (16.3%), chlorophyll a (52.7%), chlorophyll b (28.2%), antioxidant enzymes' activities, and H₂S accumulation, while it lowered the concentrations of MDA and H₂O₂. In As-treated plants, GSH and phytochelatins (PCs) were increased by MT by regulating As sequestration to make it harmless. The addition of MT increased As accumulation in the vacuoles of roots and caused the soluble fraction of As in vacuoles to become less toxic to vital organelles. MT-induced tolerance to As stress was further enhanced using NaHS, a source of H₂S. Hypotaurine (0.1 mM HT), a H₂S scavenger, was applied to the control and As-stressed plants together with MT and MT + NaHS to determine whether H₂S was implicated in MT-induced increased As-S tolerance. By reducing H₂S generation in pepper plants, HT counteracted the beneficial effects of MT, whereas the addition of NaHS to MT + HT restored the negative effects of HT, proving that H₂S is necessary for the pepper plants As-stress tolerance caused by MT.

Mitigation of Negative Effects of Chromium (VI) Toxicity in Faba Bean (Vicia faba) Plants through the Supplementation of Kinetin (KN) and Gibberellic Acid (GA3)

The present study was carried out to explore the possible role of kinetin and gibberellic acid (GA3) on faba bean under chromium (Cr) stress. Cr treatment negatively affected growth and biomass production, reduced photosynthetic pigments, and inhibited photosynthesis, gas exchange parameters, antioxidant enzymes, and the glyoxylase cycle. Moreover, Cr stress enhanced the production of malondialdehyde (MDA, 216.11%) and hydrogen peroxide (H₂O₂, 230.16%), electrolyte leakage (EL, 293.30%), and the accumulation of proline and glycine betaine. Exogenous application of kinetin and GA3 increased growth and biomass, improved pigment contents and photosynthesis, as well as up-regulated the antioxidant system by improving the antioxidant enzyme activities and the content of nonenzymatic components, and the glyoxylase cycle. Additionally, kinetin and GA3 application displayed a considerable enhancement in proline (602.61%) and glycine betaine (423.72), which help the plants to maintain water balance under stress. Furthermore, a decline in Cr uptake was also observed due to kinetin and GA3 application. Exogenous application of kinetin and GA3 ameliorated the toxic effects of Cr in faba bean plants, up-shooting the tolerance mechanisms, including osmolyte metabolism and the antioxidant system.

High pH Alleviated Sweet Orange (Citrus sinensis) Copper Toxicity by Enhancing the Capacity to Maintain a Balance between Formation and Removal of Reactive Oxygen Species and Methylglyoxal in Leaves and Roots

The contribution of reactive oxygen species (ROS) and methylglyoxal (MG) formation and removal in high-pH-mediated alleviation of plant copper (Cu)-toxicity remains to be elucidated. Seedlings of sweet orange (Citrus sinensis) were treated with 0.5 (non-Cu-toxicity) or 300 (Cu-toxicity) μM CuCl₂ × pH 4.8, 4.0, or 3.0 for 17 weeks. Thereafter, superoxide anion production rate; H₂O₂ production rate; the concentrations of MG, malondialdehyde (MDA), and antioxidant metabolites (reduced glutathione, ascorbate, phytochelatins, metallothioneins, total non-protein thiols); and the activities of enzymes (antioxidant enzymes, glyoxalases, and sulfur metabolism-related enzymes) in leaves and roots were determined. High pH mitigated oxidative damage in Cu-toxic leaves and roots, thereby conferring sweet orange Cu tolerance. The alleviation of oxidative damage involved enhanced ability to maintain the balance between ROS and MG formation and removal through the downregulation of ROS and MG formation and the coordinated actions of ROS and MG detoxification systems. Low pH (pH 3.0) impaired the balance between ROS and MG formation and removal, thereby causing oxidative damage in Cu-toxic leaves and roots but not in non-Cu-toxic ones. Cu toxicity and low pH had obvious synergistic impacts on ROS and MG generation and removal in leaves and roots. Additionally, 21 (4) parameters in leaves were positively (negatively) related to the corresponding root parameters, implying that there were some similarities and differences in the responses of ROS and MG metabolisms to Cu-pH interactions between leaves and roots.

Supplementation of nitric oxide and spermidine alleviates the nickel stress-induced damage to growth, chlorophyll metabolism, and photosynthesis by upregulating ascorbate-glutathione and glyoxalase cycle functioning in tomato

Experiments were conducted to evaluate the role of exogenously applied nitric oxide (NO; 50 µM) and spermidine (Spd; 100 µM) in alleviating the damaging effects of Ni (1 mM NiSO46H2O) toxicity on the growth, chlorophyll metabolism, photosynthesis, and mineral content in tomato. Ni treatment significantly reduced the plant height, dry mass, and the contents of glutamate 1-semialdehyde, δ-amino levulinic acid, prototoporphyrin IX, Mg-prototoporphyrin IX, total chlorophyll, and carotenoids; however, the application of NO and Spd alleviated the decline considerably. Supplementation of NO and Spd mitigated the Ni-induced decline in photosynthesis, gas exchange, and chlorophyll fluorescence parameters. Ni caused oxidative damage, while the application of NO, Spd, and NO+Spd significantly reduced the oxidative stress parameters under normal and Ni toxicity. The application of NO and Spd enhanced the function of the antioxidant system and upregulated the activity of glyoxalase enzymes, reflecting significant reduction of the oxidative effects and methylglyoxal accumulation. Tolerance against Ni was further strengthened by the accumulation of proline and glycine betaine due to NO and Spd application. The decrease in the uptake of essential mineral elements such as N, P, K, and Mg was alleviated by NO and Spd. Hence, individual and combined supplementation of NO and Spd effectively alleviates the damaging effects of Ni on tomato.

Insight into the Mechanism of Salt-Induced Oxidative Stress Tolerance in Soybean by the Application of Bacillus subtilis: Coordinated Actions of Osmoregulation, Ion Homeostasis, Antioxidant Defense, and Methylglyoxal Detoxification

Considering the growth-promoting potential and other regulatory roles of bacteria, we investigated the possible mechanism of the role of Bacillus subtilis in conferring salt tolerance in soybean. Soybean (Glycine max cv. BARI Soybean-5) seeds were inoculated with B. subtilis, either through a presoaking with seeds or a direct application with pot soil. After 20 days of sowing, both the seed- and soil-inoculated plants were exposed to 50, 100, and 150 mM of NaCl for 30 days. A clear sign of oxidative stress was evident through a remarkable increase in lipid peroxidation, hydrogen peroxide, methylglyoxal, and electrolyte leakage in the salt treated plants. Moreover, the efficiency of the ascorbate (AsA)–glutathione (GSH) pathways was declined. Consequently, the plant growth, biomass accumulation, water relations, and content of the photosynthetic pigments were decreased. Salt stress also caused an increased Na⁺/K⁺ ratio and decreased Ca²⁺. On the contrary, the B. subtilis inoculated plants showed increased levels of AsA and GSH, their redox balance, and the activities of the AsA–GSH pathway enzymes, superoxide dismutase, catalase, glutathione peroxidase, glutathione S-transferase, and peroxidase. The B. subtilis inoculated plants also enhanced the activities of glyoxalase enzymes, which mitigated methylglyoxal toxicity in coordination with ROS homeostasis. Besides this, the accumulation of K⁺ and Ca²⁺ was increased to maintain the ion homeostasis in the B. subtilis inoculated plants under salinity. Furthermore, the plant water status was uplifted in the salt treated soybean plants with B. subtilis inoculation. This investigation reveals the potential of B. subtilis in mitigating salt-induced oxidative stress in soybean plants through modulating the antioxidant defense and glyoxalase systems along with maintaining ion homeostasis and osmotic adjustments. In addition, it was evident that the soil inoculation performed better than the seed inoculation in mitigating salt-induced oxidative damages in soybean.

Modulation of osmoprotection and antioxidant defense by exogenously applied acetate enhances cadmium stress tolerance in lentil seedlings

To examine the potential role of acetate in conferring cadmium (Cd) stress tolerance in lentil (Lens culinaris), several phenotypical and physio-biochemical properties have been examined in Cd-stressed lentil seedlings following acetate applications. Acetate treatment inhibited the translocation of Cd from roots to shoots, which resulted in a minimal reduction in photosynthetic pigment contents. Additionally, acetate-treated lentil showed higher shoot (1.1 and 11.72%) and root (4.98 and 30.64%) dry weights compared with acetate-non-treated plants under low-Cd and high-Cd concentrations, respectively. Concurrently, acetate treatments increase osmoprotection under low-Cd stress through proline accumulation (24.69%), as well as enhancement of antioxidant defense by increasing ascorbic acid content (239.13%) and catalase activity (148.51%) under high-Cd stress. Acetate-induced antioxidant defense resulted in a significant diminution in hydrogen peroxide, malondialdehyde and electrolyte leakage in Cd-stressed lentil seedlings. Our results indicated that acetate application mitigated oxidative stress-induced damage by modulating antioxidant defense and osmoprotection, and reducing root-to-shoot Cd transport. These findings indicate an important contribution of acetate in mitigating the Cd toxicity during growth and development of lentil seedlings, and suggest that the exogenous applications of acetate could be an economical and new avenue for controlling heavy metal-caused damage in lentil, and potentially in many other crops.

Iron oxide nanoparticles and selenium supplementation improve growth and photosynthesis by modulating antioxidant system and gene expression of chlorophyll synthase (CHLG) and protochlorophyllide oxidoreductase (POR) in arsenic-stressed Cucumis melo

Current research reveals the positive role of iron oxide nanoparticles (IONPs) and selenium (Se) in extenuation of arsenic (As) induced toxicity in Cucumis melo. C. melo plants grown in As spiked soil (20 mg kg^-1 As) showed reduced growth, chlorophyll (Chl) content, photosynthetic rate, stomatal conductivity and transpiration. On the other hand, the alone applications of IONPs or Se improved growth and physiochemical parameters of C. melo plants. Additionally, exogenous application IONPs and Se synergistically improved the activity of antioxidative enzymes and glyoxalase system in C. melo plants. In addition, the collective treatment of IONPs and Se reduced As uptake, enhanced rate of photosynthesis and increased gas exchange attributes of C. melo plants under As stress. Interactive effect of IONPs and Se regulated reduced glutathione (GSH), oxidized glutathione (GSSG) and ascorbate (AsA) content in C. melo plants exposed to As-contaminated Soil. IONPs and Se treatment also regulated expression of respiratory burst oxidase homologue D (RBOHD) gene, chlorophyll synthase (CHLG) and protochlorophyllide oxidoreductase (POR). Therefore, the combined treatment of IONPs and Se may enhance the growth of crop plants by alleviating As stress.

Silicon-mediated metabolic upregulation of ascorbate glutathione (AsA-GSH) and glyoxalase reduces the toxic effects of vanadium in rice

Although beneficial metalloid silicon (Si) has been proven to reduce the toxicity of several heavy metals, there is a lack of understanding regarding Si potential function in mitigating phytotoxicity induced by vanadium (V). In this study, effect of Si (1.5 mM) on growth, biomass production, V uptake, reactive oxygen species (ROS), methylglyoxal (MG) formation, selected antioxidants enzymes activities, glyoxalase enzymes under V stress (35 mg L^-1) was investigated in hydroponic experiment. The results showed that V stress reduced rice growth, caused V accumulation in rice. Addition of Si to the nutritional medium increased plant growth, biomass yield, root length, root diameter, chlorophyll parameters, photosynthetic assimilation, ion leakage, antioxidant enzymes activities under V stress. Notably, Si sustained V-homeostasis and alleviated V caused oxidative stress by boosting ascorbate (AsA) levels and the activity of antioxidant enzymes in V stressed rice plants. Furthermore, Si protected rice seedlings against the harmful effects of methylglyoxal by increasing the activity of glyoxalase enzymes. Additionally, Si increased the expression of numerous genes involved in the detoxification of reactive oxygen species (e.g., OsCuZnSOD1, OsCaTB, OsGPX1, OsAPX1, OsGR2, and OsGSTU37) and methylglyoxal (e.g., OsGLYI-1 and OsGLYII-2). The findings supported that Si can be applied to plants to minimize the V availability to plant, and also induced V stress tolerance.

Beneficial role of methyl jasmonate on morphological, physiological and phytochemical responses of Calendula officinalis L. under Chromium toxicity

Contamination of soil with chromium (Cr) is a rising problem in terms of agricultural sustainability and food safety. Here, the effects of methyl jasmonate (MJ; 0, 5, and 10 µM) on alleviating Cr stress (0, 100, and 200 µM) were surveyed in pot marigold (Calendula officinalis L.). The results showed that Cr stress significantly reduced photosynthetic pigments and leaf accumulation of total soluble sugars, total starch, and mineral nutrients and, consequently, lowered the height and biomass of pot marigold plants. Chromium toxicity also increased the leaf levels of oxidative stress markers and induced oxidative stress, which was associated with damage to bio-membranes and increased levels of malondialdehyde. However, MJ supplementation reduced the leaf accumulation of Cr, increased the content of photosynthetic pigments, and improved the performance of the photosynthetic machinery in Cr-stressed plants. MJ supplementation boosted the antioxidant defense system by upregulating antioxidant enzymes, glyoxalase enzymes, and the ascorbate-glutathione (AsA-GSH) pool redox, which significantly diminished Cr-induced oxidative stress. Hence, MJ supplementation might be a practicable approach for reducing Cr absorption and its negative impacts on pot marigold plants growing under Cr-contaminated conditions. Clinical trials registration Not applicable.

Methyl jasmonate increases aluminum tolerance in rice by augmenting the antioxidant defense system, maintaining ion homeostasis, and increasing nonprotein thiol compounds

Aluminum (Al) stress is known as a serious threat to the growth and production of crops in acidic soils. Here, the effects of different concentrations of methyl jasmonate (MJ, 0.5 and 1 µM) on rice plants were investigated hydroponically under different concentrations of Al (0.5 and 1 mM). Aluminum treatments injured membrane lipids and photosynthetic apparatus by reducing the leaf contents of mineral nutrients and increasing the accumulation of free radicals (hydrogen peroxide, methylglyoxal, and superoxide anion), resulting in reduced growth and biomass of rice. In comparison to control plants, 0.5 and 1 μM Al treatments lowered height by 21 and 37% and total dry weight by 24 and 41%, respectively. Exogenously added methyl diminished the inhibitory effects of Al stress on growth and photosynthetic apparatus by restoring ion homeostasis and improving chlorophyll metabolism. The application of MJ, by inducing the activity of antioxidant enzymes and the glyoxalase cycle, lessened the levels of the toxic compounds hydrogen peroxide, methylglyoxal, and superoxide anion and, as a result, dwindled the toxic Al-induced oxidative stress. Methyl jasmonate enhanced the leaf accumulation of nonprotein thiol compounds and improved plant tolerance under Al stress by increasing the activity of enzymes involved in the synthesis of thiol compounds. Methyl jasmonate increased the leaf accumulation of glutathione and phytochelatins in Al-stressed plants by increasing the expression of GSH1, PCS, and ABCC1, which reduced the toxicity of toxic Al accumulated in leaves by sequestering toxic Al in vacuoles. Together, the results revealed that MJ increased the tolerance of rice under Al toxicity by maintaining ion homeostasis, improving the activity of antioxidant enzymes and the glyoxalase system, and increasing the level of non-protein thiol compounds. This research adds to our understanding of how MJ may be used in the future to improve Al stress tolerance in sustainable agriculture.

Foliar application of Zinc oxide nanoparticles alleviates cadmium toxicity in purslane by maintaining nutrients homeostasis and improving the activity of antioxidant enzymes and glyoxalase system

Cadmium (Cd) reduces plant growth by interfering with important plant metabolic processes at the physiological, biochemical, and molecular levels. Here, the effects of foliar application of zinc oxide nanoparticles (ZnO-NPs) on growth, antioxidant enzymes, glyoxalase system, and macro- and micro-elements levels of purslane (portulaca oleracea L.) under Cd toxicity were investigated. The results revealed that Cd toxicity increased the levels of hydrogen peroxide (H₂O₂), methylglyoxal (MG) and malondialdehyde (MDA), resulting in oxidative stress and the induction of electrolyte leakage (EL). Cd stress enhanced the leaf concentration of Cd and declined the leaf concentrations of macro- and micro-elements, resulting in a decrease in the content of photosynthetic pigments and plant growth. However, the foliar application of ZnO-NPs improved the activity of antioxidant enzymes and the glyoxalase system and, consequently, reduced the levels of H₂O₂, MG, MDA, and EL in Cd-stressed plants. ZnO-NPs decreased the leaf concentration of Cd and restored the leaf concentrations of macro- and micro-elements, thereby improving photosynthetic pigments and the growth of Cd-stressed purslane plants. In general, the results revealed that the foliar application of ZnO-NPs improved the growth of purslane plants under Cd phytotoxicity by maintaining nutrient homeostasis, improving the defense mechanisms (antioxidant enzymes and glyoxalase cycle), and increasing the accumulation of proline and glutathione. Therefore, the results of the present study strongly recommend that ZnO-NPs could be used effectively in the cultivation of plants in areas contaminated with toxic Cd metal.

Physiological defense and metabolic strategy of Pistia stratiotes in response to zinc-cadmium co-pollution

Pistia stratiotes is a cadmium (Cd) hyperaccumulating plant with strong bioaccumulation and translocation capacity for Cd. A hydroponic experiment was used to evaluate the combined effect of Zinc (Zn) and Cd at different concentrations on leaf growth and metabolism of P. stratiotes. This study revealed the physiological defense and metabolic strategy of responses to Zn-Cd co-pollution. With the Zn₅₀Cd₁, Zn₅₀Cd₁₀, Zn₁₀₀Cd_1, and Zn₁₀₀Cd₁₀ treatments for 9 d, the relative crown diameter, relative leave number, and ramet number of the plant had no significant difference with the control. Under the compound treatments containing Zn₅₀Cd₅₀ and Zn₁₀₀Cd₅₀, the activity of the glyoxalase system and amino acid metabolism in the leaves were inhibited. The leaf photosynthetic apparatus increased heat dissipation to reduce the damage to the photosystem II (PS II) reaction center caused by excess excitation energy under Zn-Cd stress. This safeguarded the balance between the absorption and utilization of light energy. Compared to the control, the Zn and Cd co-pollution for 9 d had no effect on the reduced glutathione (GSH) and oxidized glutathione (GSSG) contents. There was no effect on the dehydroascorbate reductase (DHAR) and glutathione reductase (GR) activities, but there was increased ascorbate peroxidase (APX) activity and oxidized ascorbic acid (DHA) content. These increased the antioxidant capacity of the ascorbate-glutathione (AsA-GSH) cycle. The treated plants also had increased levels of carnosol and substances related to lipid metabolism including 9, 10-Dihydroxystearate, Prostaglandin G2, Sphingosine, and 13-L-Hydroperoxylinoleic acid, maintaining the cell stability and resistance to the Zn-Cd stress.

Spermine-mediated polyamine metabolism enhances arsenic-stress tolerance in Phaseolus vulgaris by expression of zinc-finger proteins related genes and modulation of mineral nutrient homeostasis and antioxidative system

The contamination of groundwater and agricultural land by metalloids especially arsenic (As) is one of the most serious threats to people and plants worldwide. Therefore, the present study was design to explore the role of spermine (Spm)- mediated polyamine metabolism in the alleviation of arsenic (As) toxicity in common bean (Phaseolus vulgaris L.). It was noted that As stress caused reduction in the intracellular CO₂ concentration, stomatal conductivity and transpiration rate as compared to the control treatment and also impairedplant growth attributes and mineral nutrient homeostasis (sulfur, phosphorus, potassium and calcium). However, the exogenous application of Spm resulted in a considerable enhance in the content of glutathione and nitric oxide, and the activity of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), glutathione-reductase (GR), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR) in P. vulgaris seedlings grown As-contaminated soil. In addition, Spm application significantly improved the endogenous production of putrescine and spermidine accompanied along with reduction in malondialdehyde, electrolyte leakage, hydrogen peroxide, superoxide level besides enhanced methylglyoxal (MG) detoxification. Moreover, Spm treatment elevated the expression level of zinc-finger proteins related genes (PvC3H24, PvC3H25, PvC3H26 and PvC3H27) involved in abiotic stress response. The study concluded that Spm acted as an enhancing agent and improved tolerance to As-toxicity by upregulating the expression of zinc-finger proteins related genes, polyamine metabolism, Mg detoxification and antioxidant system in P. vulgaris.