Ascorbate Peroxide Research Articles

Zinc Seed Priming Alleviates Salinity Stress and Enhances Sorghum Growth by Regulating Antioxidant Activities, Nutrient Homeostasis, and Osmolyte Synthesis

Salinity is a serious abiotic stress that limits crop production and food security. Micronutrient application has shown promising results in mitigating the toxic impacts of salinity. This study assessed the impacts of zinc seed priming (ZSP) on the germination, growth, physiological and biochemical functioning of sorghum cultivars. The study comprised sorghum cultivars (JS-2002 and JS-263), salinity stress (control (0 mM) and 120 mM)), and control and ZSP (4 mM). Salinity stress reduced germination and seedling growth by increasing electrolyte leakage (EL: 60.65%), hydrogen peroxide (H2O2: 109.50%), malondialdehyde (MDA; 115.30%), sodium (Na), and chloride (Cl) accumulation and decreasing chlorophyll synthesis, relative water contents (RWC), total soluble proteins (TSPs), and potassium (K) uptake and accumulation. Nonetheless, ZSP mitigated the deleterious impacts of salinity and led to faster germination and better seedling growth. Zinc seed priming improved the chlorophyll synthesis, leaf water contents, antioxidant activities (ascorbate peroxide: APX, catalase: CAT, peroxidase: POD, superoxide dismutase: SOD), TSPs, proline, K uptake and accumulation, and reduced EL, MDA, and H2O2 production, as well as the accumulation of toxic ions (Na and Cl), thereby promoting better germination and growth. Thus, these findings suggested that ZSP can mitigate the toxicity of salinity by favoring nutrient homeostasis, antioxidant activities, chlorophyll synthesis, osmolyte accumulation, and maintaining leaf water status.

Exogenous glutathione protected wheat seedling from high temperature and water deficit damages

High temperatures (HT) and drought are two major factors restricting wheat growth in the early growth stages. This study investigated the role of glutathione (GSH) amendment (0.0, 0.5, 1.0, and 2.0 mM) to soil in mitigating the adverse effect of HT (33 °C, with 25 °C as a control), water regimes (60% of field capacity and control), and their combinations. HT decreased the length, project area, surface area, volume, and forks of the root, while drought had the reverse effect. Shoot length, leaf area, leaf relative water content, and shoot and root dry matter were significantly decreased by HT and drought, and their combined impact was more noticeable. GSH significantly promoted the root system, shoot growth, and leaf relative water content. The combined treatment reduced chlorophyll a, chlorophyll b, and total chlorophyll. However, 0.5 mM GSH raised chlorophyll a, chlorophyll b, and total chlorophyll by 28.6%, 41.4%, and 32.5%, respectively, relative to 0.0 mM GSH. At combined treatment, 0.5 mM GSH decreased malondialdehyde (MDA) by 29.5% and increased soluble protein content by 24.1%. GSH meaningfully enhanced the activity of superoxide dismutase, catalase, and ascorbate peroxide in different treatments. This study suggested that GSH could protect wheat seedlings from the adverse effects of HT and/or drought stresses.

Trehalose Induced regulations in Physio-biochemical attributes of Helianthus annuus under Lead stress

Heavy metal is a substantially severe abiotic environmental stress that is rising in many regions of the world. Current climate change circumstances and rapid industrialization increased heavy metal accumulation in soil and water. Overall, worldwide agricultural production decreased. Trehalose, a well-known plant growth regulator, is crucial in plants' responses to a variety of abiotic conditions. The Morpho-physiological and biochemical parameters were analyzed in hydroponic research to identify the possible role of trehalose in alleviating heavy metal lead acetate stress in sunflower (Helianthus annuus L.) crops. In the sole and mixed form, two Pb(C2H3O2)2 (Control and 30 micron) and one trehalose (50 M L-1) levels were used, and a half-strength Hoagland solution was used as a nutritional medium. The current study found that heavy metal stress had a significant negative impact on plant growth (root and shoot length), fresh and dry biomass, and plant water relations, as well as poor plant water relations, membrane stability, chlorophyll content, and antioxidant enzyme activities such as superoxide dismutase (SOD), peroxide (POD), ascorbate peroxide (APX), and catalase (CAT). MDA and H2O2 are the stress markers reduced by the application of trehalose. Exogenous treatment of trehalose, on the other hand, significantly mitigates the detrimental effects of metal toxicity by altering plant physiology, enhancing water relations, and providing robust antioxidant defense against heavy metal lead acetate stress. The findings of this study provide a new dimension to scientists' understanding of the beneficial usage of trehalose in plant science and offer up new research opportunities.

Biochemical Studies on Evaluation of Sunflower (Helianthus annuus L.) Genotypes for Heat Stress

Crops are facing heat stress because of rapid climate change caused by global warming. We examined these issues in sunflower by exposing the plants growing with mean maximum temperature of 32.2oC (sowing to flowering) and 36.1oC (flowering to harvest) at normal temperature (S1) and 35.3oC (sowing to flowering) and 38.3 oC (flowering to harvest) at high temperatures (S2) by staggered sowings. Antioxidative responses of sunflower were also explored by studying the Superoxide dismutase, Catalase, Peroxidises and Ascorbate peroxidise activities. A significant increase was observed in antioxidant enzyme activities under high temperature stress. The final oil composition proved to be sensitive to the timing of heat stress and reduced (13%) by high temperatures. Some innovative steps should be taken on an emergency basis to prepare plants for such stressful conditions.

The effect of melatonin on physiological, biochemical, and enzymatic properties and the expression of antioxidant genes under different irrigation regimes in wheat

A split-plot experiment was conducted based on a randomized complete block design with four replications in two years to study the effect of melatonin on the biochemical properties and the gene expression related to antioxidant enzyme activity in bread wheat. Irrigation levels (normal (FC = 80%)), mild stress (FC = 60%), and severe stress (FC = 40%)) were assigned to the main plots, and melatonin foliar applications (zero, 50, 100, 150, and 200 μM) were assigned to Subplots. Results showed that, with the intensification of water stress, the 1000 kernel weight decreased, and the activity of ascorbate peroxidase enzyme and flavonoid content increased. Also, the level of 100 μM melatonin had the highest 1000 kernel weight, flavonoid content, and ascorbate peroxidase enzyme activity. In this study, the highest number of grains per spike, biological yield, grain yield, chlorophyll a, chlorophyll b, carotenoids, and the lowest amount of malondialdehyde recorded for foliar treatment with 50 μM of melatonin under normal irrigation conditions and the highest proline content, total phenol, superoxide dismutase, and catalase were allocated to the 100 μM melatonin foliar treatment under severe water stress conditions. The synergistic effect of water deficit stress and melatonin foliar application increased the activity and expression level of genes related to antioxidant enzymes. So, the content of superoxide dismutase (21.30% and 65.16% respectively) and catalase (50.60% and 54.44% respectively) enzyme activity increased significantly under 100- and 150-mM melatonin foliar application in water severe water stress compared to the corresponding control treatment. Furthermore, mentioned melatonin levels increased the gene expression levels of superoxide dismutase (16.67% and 38.19% respectively), ascorbate peroxides (73.76% and 47.57% respectively), polyphenol oxidase (39.32 and 51.15%) and catalase (39.95% and 50.0% respectively) under an extreme water shortage compared with corresponding control treatment. In general, the application of 100- and 150-mM melatonin induced resistance to water deficit stress in wheat by increasing the expression of antioxidant genes.

Biochemical changes of rice genotypes against blast (Magnaporthe oryzae) disease and SSR marker validation for resistance genes

Rice blast caused by Magnoporthe oryzae is a major devastating fungal disease and represents a potential threat to world rice productions. However, information about the genetic and biochemical basis of disease tolerance is still limited. In this study, we tested the presence and diversity of resistant R genes using SSR markers, and the antioxidant enzymes catalase (CAT), ascorbate peroxidise (APX) and guaicol peroxidise (POD), activity and also the concentration of hydrogen peroxide (H2O2) and malondialdehyde (MDA) in resistant (BAUdhan 3) and susceptible (BRRIdhan 28) genotype. Molecular marker analysis reveals the presence of all ten studied resistant genes in BAUdhan 3. Among the markers studied, three markers namely RM224, RM72 and RM206 produce distinct band only in resistant genotype BAUdhan 3, which might be used to screen resistant genotypes. The enzymatic activity of APX, CAT and POD increased in the inoculated plant for both cultivars but the increase was more prominent for BAUdhan 3. The M. oryzae infections significantly increased the H2O2 content in BRRIdhan 28 and not much changed in BAUdhan 3. The MDA concentration was higher in the leaves of inoculated plants of BRRIdhan 28. The higher activities of APX and POD in the leaves of the inoculated plants of BAUdhan 3 resulted in lower H2O2 accumulation which can minimize the cellular damages possibly caused by reactive oxygen species. The result shows that the presence of more resistance genes and an effective antioxidative system in BAUdhan 3, which limits the damage caused due to fungal infection and thus contributes to greater resistance.

Future Climate CO2 Reduces the Tungsten Effect in Rye Plants: A Growth and Biochemical Study.

Heavy metal pollution is one of the major agronomic challenges. Tungsten (W) exposure leads to its accumulation in plants, which in turn reduces plant growth, inhibits photosynthesis and induces oxidative damage. In addition, the predicted increase in CO2 could boost plant growth under both optimal and heavy metal stress conditions. The aim of the present study was to investigate the effect of W on growth, photosynthetic parameters, oxidative stress and redox status in rye plants under ambient and elevated (eCO2) levels. To this end, rye plants were grown under the following conditions: ambient CO2 (aCO2, 420 ppm), elevated CO2 (eCO2, 720 ppm), W stress (350 mg kg-1 soil) and W+eCO2. W stress induced significant (p < 0.05) decreases in growth and photosynthesis, increases in oxidative damages (lipid peroxidation) and the antioxidant defense system, i.e., ascorbate (ASC), reduced glutathione (GSH), GSH reductase (GR), peroxidase (POX), catalase (CAT), superoxide dismutase (SOD), ASC peroxide (APX) and dehydroascorbate reductase (DHAR). On the other hand, eCO2 decreased W uptake and improved photosynthesis, which sequentially improved plant growth. The obtained results showed that eCO2 can decrease the phytotoxicity risks of W in rye plants. This positive impact of eCO2 on reducing the negative effects of soil W was related to their ability to enhance plant photosynthesis, which in turn provided energy and a carbon source for scavenging the reactive oxygen species (ROS) accumulation caused by soil W stress.

Organic Amendments Improved the Productivity and Bio-Fortification of Fine Rice by Improving Physiological Responses and Nutrient Homeostasis under Salinity Stress.

Salinity stress (SS) is major abiotic stress that is seriously limiting crop production across the globe. The application of organic amendments (OA) mitigate the effects of salinity and improves soil health and crop production on a sustainable basis. However, limited studies are conducted to determine the impact of farmyard manure (FYM) and press mud (PM) on the performance of rice crop. Therefore, we performed this study to determine the impacts of FYM and PM on the growth, physiological and biochemical attributes, yield, and grain bio-fortification of rice crop under SS. The experiment was comprised of SS levels; control, 6 and 12 dS m-1 SS and OA; control, FYM: 5%, press mud 5% and combination of FYM (5%) + PM (5%). Soil salinity imposed deleterious impacts on the growth, yield, and grain quality of rice, however, OA appreciably offset the deleterious impacts of SS and improved the growth, yield, and grain bio-fortification of rice crop. The combined application of FYM + PM improved the growth and yield of rice through an increase in chlorophyll contents, leaf water contents, anti-oxidant activities (ascorbate peroxidise: APX; catalase: CAT, peroxidise: POD and ascorbic acid: AsA), K+ accumulation and decrease in Na+/K+ ratio, electrolyte leakage, malondialdehyde (MDA), hydrogen peroxide (H2O2), Na+ accumulation. Moreover, the combined application of FYM + PM significantly improved the grain protein (5.84% and 12.90%), grain iron (40.95% and 42.37%), and grain zinc contents (36.81% and 50.93%) at 6 and 12 dS m-1 SS. Therefore, this study suggested that the application of FYM and PM augmented the growth, yield, physiology, biochemistry, and grain bio-fortification of rice and proved to be a good practice for better rice production in salt-affected soils.

Foliar applied proline and acetic acid improves growth and yield of wheat under salinity stress by improving photosynthetic pigments, physiological traits, antioxidant activities and nutrient uptake

Salinity stress (SS) is serious abiotic stress and a major limiting factor for crop productivity and global food security. In this context, the application of osmolytes is considered as an environmental friend approach to improve plant growth under SS. Thus, the present study was conducted to determine the impact of foliar applied proline (Pro) and acetic acid (AA) on growth, yield, physiological traits, photosynthetic pigments, ionic homeostasis and antioxidant activities of wheat under SS. The study contained SS levels 0, 6 and 12 dS m-1 and foliar spray of Pro and AA; water spray, Pro (75 mM), AA (15 mM) and AA (30 mM). The study was conducted in a completely randomized design with the factorial arrangement. Salinity stress significantly reduced wheat growth and yield, by decreasing relative water contents (-49.07%), photosynthetic pigments, free amino acids (FAA: -44.79%), total soluble proteins (TSP: -15.94%) and increasing the electrolyte leakage (EL: +27.28%), hydrogen peroxide (H2O2: +51.86%), and malondialdehyde (MDA: +36.91%) accumulation. The foliar spray of Pro and AA markedly improved the wheat growth and productivity through enhanced photosynthetic pigments, RWC, FAA, TSP, antioxidant activities (catalase: CAT, ascorbate peroxide: APX: peroxidase: POD), K+ and Ca2+ uptake and decreasing EL, MDA and H2O2 accumulation and restricted entry of toxic ions (Na+ and Cl-1). Therefore, foliar application of AA and Pro effectively improves the growth and yield of wheat under SS by strengthening the antioxidant defense system, and maintaining ionic homeostasis and physiological performance.

Post-harvest chitosan treatment suppresses oxidative stress by regulating reactive oxygen species metabolism in wounded apples.

Mechanical wound on fruit triggers the formation of reactive oxygen species (ROS) that weaken cell walls, resulting in post-harvest losses. This mechanism can be controlled by using fruit preservatives to stimulate fruit antioxidant enzyme activities for the detoxification of ROS. Chitosan is a safe and environmentally friendly preservative that modulates ROS in whole fruits and plant cells, but the effects of chitosan on the ROS metabolism of mechanically wounded apples during storage are unknown. Our study focused on exploring the effects of post-harvest chitosan treatment on ROS production, cell membrane integrity, and enzymatic and non-enzymatic antioxidant systems at fruit wounds during storage. Apple fruits (cv. Fuji) were artificially wounded, treated with 2.5% (w/v) chitosan, and stored at room temperature (21–25°C, RH = 81–85%) for 7 days. Non-wounded apples were used as healthy controls. The results showed that chitosan treatment stimulated the activities of NADPH oxidase and superoxide dismutase and increased the formation of superoxide anions and hydrogen peroxide in fruit wounds. However, malondialdehyde, lipoxygenase, and membrane permeability, which are direct biomarkers to evaluate lipid peroxidation and membrane integrity, were significantly decreased in the wounded fruits after chitosan treatment compared to the wounded control fruits. Antioxidant enzymes, such as peroxidase and catalase activities, were induced by chitosan at fruit wounds. In addition, ascorbate-glutathione cycle-related enzymes; ascorbate peroxide, monodehydroascorbate reductase, dehydroascorbate reductase, and glutathione reductase and the content of substrates, mainly ascorbic acid, dehydroascorbate, reduced glutathione, and glutathione, were increased at fruit wounds by chitosan compared to the wounded control fruits. Our results show that wounding stimulated the production of ROS or oxidative stress. However, treatment with chitosan triggered antioxidant systems to scavenge ROS and prevent loss of fruit membrane integrity. Therefore, chitosan promises to be a favorable preservative in inducing tolerance to stress and maintaining fruit quality.

Improved drought tolerance of EMS mutagenized Alfalfa (Medicago sativa L.) mutants by in vitro screening at germination stage

The objectives of this study were to determine drought tolerant novel mutant of alfalfa (Medicago sativa L.) genotypes by screening EMS mutagenized 340675 M3 seeds at germination stages in the presence of osmotic stress of 35% PEG6000. Root growth assay provided several drought tolerant candidate mutants. Of those, 4 mutants were further evaluated at water deficit conditions applied for 24 days after the first cutting at flowering bud stage. The results revealed that mutants determined as drought tolerant at germination stage were also tolerant to water deficit conditions. Protein content and superoxide dismutase values were found to be higher in all mutants than controls. Ascorbate peroxides, glutton reductase and lipid peroxidase values varied based on the mutant genotype and duration of drought stress. Drought stress significantly changed transcriptional levels of MtP5CS, MtDehyd, MseIF-2, MtRD2 and MsNAC genes. These results indicated that in vitro screening of alfalfa mutant seeds for osmatic tolerance at germination and early seedling growth stages was successfully able to determine the drought tolerant alfalfa mutants which were also tolerant to water deficit conditions after the first cutting at flowering bud stage.

Organic amendments mitigate salinity induced toxic effects in maize by modulating antioxidant defense system, photosynthetic pigments and ionic homeostasis

Salinity stress (SS) is a major and increasing abiotic stress adversely affecting plant growth and productivity across the globe. The application of organic amendments (OA) is considered to be an important practice to mitigate the adverse impacts of SS. Therefore, this study was performed to assess the impact of different OA on growth, physiology and anti-oxidant activities of maize plants grown under SS. The study was comprised of diverse SS levels; 0, 6 and 12 dS m-1, and different OA; control, cow manure (CM: 5%), sugarcane pressmud (SPM: 5%) and combination of CM (2.5%) + SPM (2.5%). The study was conducted in a completely randomized design with factorial arrangement having three replications. The results indicated that SS reduced the growth and biomass production, relative water contents (RWC), chlorophyll contents, free amino acids (FAA), total soluble proteins (TSP) and increased the electrolyte leakage (EL: 40.92%), hydrogen peroxide (H2O2: 68.49%), malondialdehyde (MDA: 42.13%), and catalase (CAT: 34.24%) and ascorbate peroxide (APX: 25.70%). The application of OA significantly improved the maize growth under SS. However, the application of SPM (5%) significantly increased growth and biomass production by decreasing EL, MDA and H2O2 accumulation and increasing RWC, chlorophyll, CAT, POD, and anthocyanin, TSP and FAA. These findings suggest that application of SPM improved the growth and biomass production of maize by improving anti-oxidant activities, photosynthetic pigments, TSP, FAA reducing lipid peroxidation and EL.

Effects of Chilling Stress on Morphological, Physiological, and Biochemical Attributes of Silage Corn Genotypes during Seedling Establishment.

Chilling stress is one of the major abiotic stresses which hinder seedling emergence and growth. Herein, we investigated the effects of chilling/low temperature stress on the morphological, physiological, and biochemical attributes of two silage corn genotypes during the seedling establishment phase. The experiment was conducted in a growth chamber, and silage corn seedlings of Yukon-R and A4177G-RIB were grown at optimum temperature up to V3 stage and then subjected to five temperature regimes (25 °C as control, 20 °C, 15 °C, 10 °C, and 5 °C) for 5 days. After the temperature treatment, the morphological, physiological, and biochemical parameters were recorded. Results indicated that temperatures of 15 °C and lower significantly affected seedling growth, photosynthesis system, reactive oxygen species (ROS) accumulation, and antioxidant enzyme activities. Changes in seedlings’ growth parameters were in the order of 25 °C > 20 °C > 15 °C > 10 °C > 5 °C, irrespective of genotypes. The chlorophyll content, photosynthetic rate, and maximal photochemical efficiency of PS-II (Fv/Fm) were drastically decreased under chilling conditions. Moreover, chilling stress induced accumulation of hydrogen peroxide (H2O2)and malonaldehyde (MDA) contents. Increased proline content and enzymatic antioxidants, including superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxide (APX), were found to alleviate oxidative damage under chilling stress. However, the genotype of Yukon-R exhibited better adaption to chilling stress than A4177G3-RIB. Yukon-R showed significantly higher proline content and enzymatic antioxidant activities than A4177G3-RIB under severe chilling conditions (temperature ≤ 10 °C). Similarly, Yukon-R expressed low temperature-induced ROS accumulation. Furthermore, the interaction effects were found between temperature treatment and genotype on the ROS accumulation, proline content and antioxidant enzyme activities. In summary, the present study indicated that Yukon-R has shown better adaptation and resilience against chilling temperature stress, and therefore could be considered a potential candidate genotype to be grown in the boreal climate.

Combined effects of vermicompost and vermicompost leachate on the early growth of Meloidogyne incognitastressed Withania somnifera (L.) Dunal.

Roots of Withania somnifera, an important medicinal herb, are prone to the infection of Meloidogyne incognita (a root parasitic nematode). The infection lowers the quality and quantity of plant material and poses a challenge in crop cultivation and obtaining desirable yield. In the present study, in vitro inhibitory activity of vermicompost leachate (Vcom-L) was assessed against % hatch and survival of M. incognita in a 96h assay. Then, Vcom-L was used as soil supplement in combination with vermicompost (Vcom) to evaluate their nematode inhibitory and stress alleviating effect in W. somnifera, in a pot experiment. Root galling intensity and growth performance of nematode-stressed W. somnifera raised from seeds pre-soaked in distilled water (DW), Vcom-L, vermicompost tea (Vcom-T) and different dilutions of Vcom-L were assessed. We observed 79% suppression of egg hatching and 89% juvenile (J2) mortality after 96h compared to control, at 100% concentration of Vcom-L. Significant reduction in gall formation with increase in growth parameters of seedlings was observed after combined application of Vcom (60% or 100%) + Vcom-L and was evident as enhancement in seedling biomass and contents of chlorophyll and protein. However, proline, total phenolics and malondialdehyde (MDA) content declined significantly in these combinations compared to the control (0% Vcom). Activity of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidise (APX), guaiacol peroxidise (GPX) and glutathione reductase (GR) declined with Vcom as well as Vcom + Vcom-L and corresponded with decline in the accumulation of reactive oxygen species in leaves. Further, 1:5 and 1:10 dilutions of Vcom-L in combination with Vcom (60%) proved beneficial in mitigating the nematode-induced stress in W. somnifera. Present results showed the potential of Vcom and Vcom-L in standardised combination as an effective strategy in controlling the pathogenicity of M. incognita in medicinal plants such as W. somnifera.

Salicylic acid-mediated enhancement of resistance in tomato plants against Xanthomonas perforans

IntroductionBacterial spot disease of tomato was identified a few decades ago. The varying point of entry for the pathogen has enhanced the complexities for designing an effective disease management method. Recent advances in the use of inducers to elicit immune response in order to prepare the plant for a future attack by the pathogen are similar to the vaccination that is undertaken in humans and is a trending technology. ObjectivesThe present study aims at understanding the effect of salicylic acid (SA) for management of bacterial spot disease caused by Xanthomonas perforans. MethodsThe study evaluated the effects of SA on the disease incidence along with seed germination and seedling vigor in two cultivars of tomato namely, Sun hybrid- resistant variety (R) and Quality- highly susceptible variety(HS) ResultsThe germination and seedling vigor, which was reduced in case of HS variety in comparison with that of the R variety, was notably improved after seed priming in both the cultivars. The antioxidant enzyme activities of ascorbate peroxidise (APx), catalase (CAT) and glutathione reductase (GR) were assessed which showed that the R variety reached maximum activity at 18 h post inoculation (hpi), 24 hpi and 21 hpi, respectively, whereas the HS variety reached maximum at 30 hpi for APx and 36 hpi for CAT and GR activities. The transcript accumulation using qRT-PCR was also evaluated showing mRNA accumulation was maximum in the R cultivar after SA priming at 1.5 mM concentration. Conclusionthe present study demonstrates the potential benefits of seed priming with SA to effectively elicit defence response in tomato seedlings against the bacterial spot disease.

Incorporated Biochar-Based Soil Amendment and Exogenous Glycine Betaine Foliar Application Ameliorate Rice (Oryza sativa L.) Tolerance and Resilience to Osmotic Stress.

Osmotic stress is a major physiologic dysfunction that alters the water movement across the cell membrane. Soil salinity and water stress are major causal factors of osmotic stress that severely affect agricultural productivity and sustainability. Herein, we suggested and evaluated the impact of integrated biochar-based soil amendment and exogenous glycine betaine application on the growth, physiology, productivity, grain quality, and osmotic stress tolerance of rice (Oryza sativa L., cv. Sakha 105) grown in salt-affected soil under three irrigation intervals (6, 9, or 12 days), as well as soil properties and nutrient uptake under field conditions during the 2019 and 2020 seasons. Our findings showed that dual application of biochar and glycine betaine (biochar + glycine betaine) reduced the soil pH, electrical conductivity, and exchangeable sodium percentage. However, it enhanced the K+ uptake which increased in the leaves of treated-rice plants. Additionally, biochar and glycine betaine supplementation enhanced the photosynthetic pigments (chlorophyll a, b, and carotenoids) and physiological attributes (net photosynthetic rate, stomatal conductance, relative water content, and electrolyte leakage) of osmotic-stressed rice plants. Biochar + glycine betaine altered the activity of antioxidant-related enzymes (catalase, ascorbate peroxide, and peroxidase). Moreover, it improved the yield components, biological yield, and harvest index, as well as the nutrient value of rice grains of osmotic-stressed rice plants. Collectively, these findings underline the potential application of biochar and glycine betaine as a sustainable eco-friendly strategy to improve plant resilience, not only rice, but other plant species in general and other cereal crops in particular, to abiotic stress, particularly those growing in salt-affected soil.

Phytoremediation of soil treated with metalliferous leachate from an abandoned industrial site by Alternanthera sessilis and Ipomoea aquatica: Metal extraction and biochemical responses

Metalliferous soil (MS) was collected from near an abandoned pulp and paper mill, and leachates were extracted in water to simulate natural water percolation. Metalliferous soil leachates (MSL) were added to the garden soil, and phytoremediation trials were carried out by Alternanthera sessilis and Ipomoea aquatica for 28-d in pot experiments. The aqueous leachates could extract 18–33% of the metals from the MS. The maximum accumulation of 38–43 μg Cd/g, 211–294 μg Pb/g, 199–218 μg Cr/g, 92–95 μg Ni/g, 422–511 μg Cu/g, 2366–3531 μg Zn/g, 6910–6105 μg Fe/g, and 4410–5576 μg Mn/g in the plants exceeded the respective toxic ranges, indicating their tolerance. Plants showed >50% removal efficiency for Pb, Cr, and Cu. For other metals, variable removal efficiency between 25 and 48% was also noted. The root morphology and X-ray microanalysis revealed Pb, Cr, and Fe deposits that influenced their uptake and possible interactions with other elements. The treated plants showed reduced chlorophylls, carotenoids, protein, and ascorbate, along with an increase in superoxide radical, hydrogen peroxide, and lipid peroxidation. A concomitant increase in the activities of all the vital antioxidant enzymes such as superoxide dismutase, catalase, ascorbate peroxidise, and guaiacol peroxidise helped to combat multi-metal stress in them. Overall, owing to their metal uptake efficiency, significant oxidative stress mitigation properties, rapid growth rate, and large biomass, A. sessilis, and I. aquatica can be recommended for use in the decontamination of multiple metals.

Mesorhizobium ciceri as biological tool for improving physiological, biochemical and antioxidant state of Cicer aritienum (L.) under fungicide stress

Fungicides among agrochemicals are consistently used in high throughput agricultural practices to protect plants from damaging impact of phytopathogens and hence to optimize crop production. However, the negative impact of fungicides on composition and functions of soil microbiota, plants and via food chain, on human health is a matter of grave concern. Considering such agrochemical threats, the present study was undertaken to know that how fungicide-tolerant symbiotic bacterium, Mesorhizobium ciceri affects the Cicer arietinum crop while growing in kitazin (KITZ) stressed soils under greenhouse conditions. Both in vitro and soil systems, KITZ imparted deleterious impacts on C. arietinum as a function of dose. The three-time more of normal rate of KITZ dose detrimentally but maximally reduced the germination efficiency, vigor index, dry matter production, symbiotic features, leaf pigments and seed attributes of C. arietinum. KITZ-induced morphological alterations in root tips, oxidative damage and cell death in root cells of C. arietinum were visible under scanning electron microscope (SEM). M. ciceri tolerated up to 2400 µg mL−1 of KITZ, synthesized considerable amounts of bioactive molecules including indole-3-acetic-acid (IAA), 1-aminocyclopropane 1-carboxylate (ACC) deaminase, siderophores, exopolysaccharides (EPS), hydrogen cyanide, ammonia, and solubilised inorganic phosphate even in fungicide-stressed media. Following application to soil, M. ciceri improved performance of C. arietinum and enhanced dry biomass production, yield, symbiosis and leaf pigments even in a fungicide-polluted environment. At 96 µg KITZ kg−1 soil, M. ciceri maximally and significantly (p ≤ 0.05) augmented the length of plants by 41%, total dry matter by 18%, carotenoid content by 9%, LHb content by 21%, root N by 9%, shoot P by 11% and pod yield by 15% over control plants. Additionally, the nodule bacterium M. ciceri efficiently colonized the plant rhizosphere/rhizoplane and considerably decreased the levels of stressor molecules (proline and malondialdehyde) and antioxidant defence enzymes viz. ascorbate peroxidise (APX), guaiacol peroxidise (GPX), catalase (CAT) and peroxidises (POD) of C. arietinum plants when inoculated in soil. The symbiotic strain effectively colonized the plant rhizosphere/rhizoplane. Conclusively, the ability to endure higher fungicide concentrations, capacity to secrete plant growth modulators even under fungicide pressure, and inherent features to lower the level of proline and plant defence enzymes makes this M. ciceri as a superb choice for augmenting the safe production of C. arietinum even under fungicide-contaminated soils.

Exogenous arginine modulates leaf antioxidant enzymes and hydrogen peroxide content in tomato plants under transient heat stresses

ABSTRACT Heat stress can impact crop development and yield and amino acids play diverse essential roles in plants. This work aimed to study the long-term effects of foliar spray with L-arginine in antioxidant machinery, physiology, nutrition, productivity and fruit quality of tomato plants subjected to transient heat stresses. Six concentrations of L-arginine were sprayed on the plants: 0 (control), 0.10, 0.25, 0.50, 1.0 and 2.0 g·L–1. The content of hydrogen peroxide (H2O2), a reactive oxygen species, decreased concurrently to the increasing arginine concentration. The ascorbate peroxide (APX) activity had an inverse behavior to that observed for H2O2 content (r = –0.79), not only indicating that arginine is able to modulate APX, but also suggesting that this enzyme plays an important role on the mitigation of H2O2 generation under heat stress. Ascorbate peroxide and catalase (CAT) activities had a positive correlation (r = 0.82), showing that these enzymes may work in tandem. The influence of arginine on photosynthesis activity and gas exchange was generally weak and depended mainly on the plant developmental stage. Yield was increased by 19.8 and 23.1% in plants that received 1.0 and 0.5 g·L–1 of arginine, respectively, when compared to control plants. In conclusion, the use of exogenous L-arginine can protect tomato plants against oxidative imbalance under transient heat within protected environments.

Effects of gallic acid grafted chitosan on improving light fastness of cotton fabric dyed with gardenia yellow

Antioxidants can inhibit the photofading of natural dyes. However, their effects on improving the light fastness of fabrics dyed with natural dyes are still limited since no stable covalent bonds formed between their molecules and the substrate in the conventional dipping and padding method. In this study, one antioxidant, gallic acid, was grafted to chitosan via the redox reaction between ascorbic acid and hydrogen peroxide. The grafted chitosan was then cross-linked onto cotton fabric dyed with gardenia yellow. Results of colour change caused by the exposure of treated fabric to simulated sunlight irradiation show that gallic acid grafted chitosan (GA-g-CTS) inhibited photofading of gardenia yellow on cotton. Results from handle test show that although the softness of cotton fabric cross-linked with GA-g-CTS slightly deteriorated, the overall handle of the treated fabric was not distinctly affected.