Antioxidant Scavenging Enzymes Research Articles

Effects of exogenous spermidine and spermine on antioxidant metabolism associated with cold-induced leaf senescence in Zoysiagrass (Zoysia japonica Steud.)

Zoysiagrass (Zoysia japonica Steud.) leaves lose their green colour as they undergo cold acclimation (CA) in late fall in many regions, and delaying leaf senescence can extend their green period. The objective of this study was to investigate whether exogenous spermidine (Spd) and spermine (Spm) can delay leaf senescence by enhancing reactive oxygen species (ROS)-scavenging antioxidant enzyme activity. Mature zoysiagrass (cv. Zenith) plants were treated with Spm (1 mM) or Spd (1 mM) or water (control). The treated plants were grown under normal conditions or subjected to cold acclimation CA for 35 days. CA treatment increased leaf electrolyte leakage (EL) and malondialdehyde (MDA) level, decreased chlorophyll (Chl) content, and induced leaf senescence. Foliar application of Spd and Spm reduced the decline in Chl content and reduced EL and MDA levels. CA treatment increased the ROS level and reduced antioxidant enzyme activity. Application of Spm and Spd reduced ROS accumulation and enhanced the activities of superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase under CA conditions. The results of this study indicated that exogenous Spd and Spm at 1 mM can delay CA-induced leaf senescence through enhancement of ROS-scavenging antioxidant activity in zoysiagrass.

Preservation of Ginkgo biloba seeds by coating with chitosan/nano-TiO2 and chitosan/nano-SiO2 films

In this study, the chitosan, chitosan/nano-TiO2 and chitosan/nano-SiO2 coating films were prepared, their physico-chemical properties were determined. Then the preservation of Ginkgo biloba seeds coating with these films were investigated during storage. The incorporation of nano-TiO2 and nano-SiO2 particles of the best formula enhanced the mechanical properties of the composite films, which improved the water-vapor and gas permeability. Chitosan coating incorporation of nano-TiO2 and nano-SiO2 particles could significantly decrease the decay rate, shrinkage rate, respiration rate, ethylene production rate, electrolyte leakage rate, superoxide anion (O2·−) production rate and the accumulation of malondialdehyde (MDA) content. After storage, the firmness of G. biloba seeds coated with chitosan alone and chitosan/nanocomposite were markedly higher than those of control. Higher activities of scavenger antioxidant enzymes including peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) were enhanced in the chitosan/nano-TiO2 and chitosan/nano-SiO2 coating treatments during storage time. Either the composite treatment of chitosan with nano-TiO2 or chitosan/nano-SiO2 exhibited desirable performance in inhibiting mildew occurrence, shrinkage and maintaining the firmness of G. biloba seeds, positively affect the antioxidant activity in G. biloba seeds, thereby leading to the enhancement of seed quality. Coating G. biloba seeds with chitosan/nano-TiO2 or chitosan/nano-SiO2 is a potential method for commercial preservation.

Foliar application of organic and inorganic iron formulation induces differential detoxification response to improve growth and biofortification in soybean

Foliar fertilization for biofortification is a targeted, economic and environment friendly approach rather than soil fertilization. In this study, we identified the appropriate growth stage(s) and right foliar iron (Fe) formulation in enhancing growth and Fe biofortification in soybean. In addition, we studied the physiological mechanism adopted by plants to endure foliar supplied Fe. For this purpose, a field experiment was conducted to evaluate various organic and inorganic Fe formulations such as Fe-citrate, FePO4, humic acid (HA) + Fe, HA alone and nano-Fe along with control (deionized water) in soybean (Glycine max var. DS-2614). Plants were sprayed at flowering (Set I), pod filling (Set II) and at both stages (Set III). Biomass and leaf area were significantly enhanced with application of Fe-citrate and FePO4 followed by HA + Fe. The yield traits (pod number, seed yield, test weight) significantly increased with HA + Fe and nano-Fe application. Enhanced Fe accumulation in seed was observed with HA + Fe followed by Fe-citrate and nano-Fe treatment. Foliar application of Fe at pod filling stage improved growth whereas yield and Fe fortification improved in Set III. This response may be attributed to enhanced activities of antioxidant scavenging enzymes and reduced lipid peroxidation in leaves treated with HA + Fe followed by FePO4. Results suggest foliar application of HA + Fe (organic Fe) and nano-Fe to be promising for soybean in improving growth and seed Fe content.

Micronucleus frequency is correlated with antioxidant enzyme levels in workers occupationally exposed to pesticides.

Oxidative stress can cause DNA damage leading to nuclear anomalies such as micronuclei (MN). Antioxidant enzymes involved in protection against intracellular oxidative stress include glutathione peroxidase (GPx), glutathione reductase (GR), superoxide dismutase (SOD), and catalase (CAT). Pesticide exposure induces oxidative stress and alters antioxidant defense mechanisms, including detoxification and scavenger enzymes. The aim of this study was to evaluate MN frequency in workers occupationally exposed to pesticides and their relationship with antioxidant enzyme activities. A cross-sectional study was conducted in 201 individuals, some of whom were dedicated to the spraying of pesticides. The cytokinesis-block micronucleus (CBMN) assay was conducted, and the activities of GPx, GR, SOD, and CAT were determined. The geometric mean (GM) of MN was 5.4 (1-26 MN). The GM for the antioxidant enzymes was 198.68U/mL for GPx, 38.96U/g Hb for GR, 94.78U/mL for SOD, and 69.77U/g Hb for CAT. There was a lower MN frequency in males than that in females, and a higher nuclear index. In addition, age affected MN frequency. There was a negative correlation between MN frequency and GPx activity, but a positive one between MN frequency and GR activity. These findings suggest the involvement of GPx in MN frequency.

Exogenous ascorbic acid improved tolerance in maize (Zea mays L.) by increasing antioxidant activity under salinity stress

Salinity causes additional manufacture of reactive oxygen species (ROS) in plants, and ascorbate plays important role in maintaining of ROS scavenging antioxidant enzymes. In this study, the role of exogenous ascorbic acid (AsA) was examined on growth, chlorophyll and oxidative stress related enzymatic and non-enzymatic antioxidants in three maize hybrids under NaCl mediated salt stress. In hydroponic culture, AsA was applied at 0.5 and 1.0 mM with and without 12 dSm-1 NaCl, each treatment comprised two independent experiments with three replications. After four weeks, plants were harvested for recording growth and biochemical parameters. Root length, shoot length, dry matter accumulation, chlorophyll (Chl a and Chl b), AsA, reduced glutathione (GSH) and activity of ascorbate peroxidase (APX) were markedly reduced by salt stress, while H2O2 and Malondialdehyde (MDA) content were increased significantly. Exogenous application of AsA in saline treatment significantly improved root length, shoot length, dry matter accumulation, chlorophyll, AsA, GSH and APX activity while it decreased the contents of oxidized glutathione (GSSG) significantly in all the hybrids. However, content of dehydroascorbate (DHA) was reduced only in 900M Gold and PS-999. On the other hand, activity of monodehydroascorbatereductase (MDHAR) was increased only in Super gold and 900M gold (by 0.5 mM AsA) while dehydroascorbatereductase (DHAR) activity increased in Super gold only. The results of the present study evidently concluded that exogenous AsA application responded differentially in maize genotypes under salt stress and mitigated the negative effects of salinity. Key words: Maize, salinity, reactive oxygen species, antioxidant, ascorbic acid.

English

Salinity causes additional manufacture of reactive oxygen species (ROS) in plants, and ascorbate plays important role in maintaining of ROS scavenging antioxidant enzymes. In this study, the role of exogenous ascorbic acid (AsA) was examined on growth, chlorophyll and oxidative stress related enzymatic and non-enzymatic antioxidants in three maize hybrids under NaCl mediated salt stress. In hydroponic culture, AsA was applied at 0.5 and 1.0 mM with and without 12 dSm-1 NaCl, each treatment comprised two independent experiments with three replications. After four weeks, plants were harvested for recording growth and biochemical parameters. Root length, shoot length, dry matter accumulation, chlorophyll (Chl a and Chl b), AsA, reduced glutathione (GSH) and activity of ascorbate peroxidase (APX) were markedly reduced by salt stress, while H2O2 and Malondialdehyde (MDA) content were increased significantly. Exogenous application of AsA in saline treatment significantly improved root length, shoot length, dry matter accumulation, chlorophyll, AsA, GSH and APX activity while it decreased the contents of oxidized glutathione (GSSG) significantly in all the hybrids. However, content of dehydroascorbate (DHA) was reduced only in 900M Gold and PS-999. On the other hand, activity of monodehydroascorbatereductase (MDHAR) was increased only in Super gold and 900M gold (by 0.5 mM AsA) while dehydroascorbatereductase (DHAR) activity increased in Super gold only. The results of the present study evidently concluded that exogenous AsA application responded differentially in maize genotypes under salt stress and mitigated the negative effects of salinity.   Key words: Maize, salinity, reactive oxygen species, antioxidant, ascorbic acid.

Thyroid Hormones and Oxidative Stress

ABSTRACT Thyroid hormones have a pro-oxidant effect and cause increased lipid peroxidation. Lipid peroxidation is an extremely damaging process implicated in many diseases and could be a causative factor, responsible for the varied systemic manifestations of hyperthyroidism, like myopathy and myocardial insufficiency. The activities of antioxidant scavenging enzymes like erythrocyte superoxide dismutase, catalase, and glutathione peroxidase, which prevent lipid peroxidation, are also significantly affected by hyperthyroidism and hypothyroidism. Further, it has been observed in various studies that hypothyroidism does induce changes in free radical scavenging enzymes opposite to those observed in hyperthyroidism. Oxidative injury, therefore, is an important mechanism in the pathophysiology of hyperthyroidism. How to cite this article Kesar V. Thyroid Hormones and Oxidative Stress. Indian J Med Biochem 2017;21(1):58-61.

Increased mitochondrial superoxide in the brain, but not periphery, sensitizes mice to angiotensin II-mediated hypertension

Angiotensin II (AngII) elicits the production of superoxide (O2•−) from mitochondria in numerous cell types within peripheral organs and in the brain suggesting a role for mitochondrial-produced O2•− in the pathogenesis of hypertension. However, it remains unclear if mitochondrial O2•− is causal in the development of AngII-induced hypertension, or if mitochondrial O2•− in the absence of elevated AngII is sufficient to increase blood pressure. Further, the tissue specific (i.e. central versus peripheral) redox regulation of AngII hypertension remains elusive. Herein, we hypothesized that increased mitochondrial O2•− in the absence of pro-hypertensive stimuli, such as AngII, elevates baseline systemic mean arterial pressure (MAP), and that AngII-mediated hypertension is exacerbated in animals with increased mitochondrial O2•− levels. To address this hypothesis, we generated novel inducible knock-down mouse models of manganese superoxide dismutase (MnSOD), the O2•− scavenging antioxidant enzyme specifically localized to mitochondria, targeted to either the brain subfornical organ (SFO) or peripheral tissues. Contrary to our hypothesis, knock-down of MnSOD either in the SFO or in peripheral tissues was not sufficient to alter baseline systemic MAP. Interestingly, when mice were challenged with chronic, peripheral infusion of AngII, only the MnSOD knock-down confined to the SFO, and not the periphery, demonstrated an increased sensitization and potentiated hypertension. In complementary experiments, over-expressing MnSOD in the SFO significantly decreased blood pressure in response to chronic AngII. Overall, these studies indicate that mitochondrial O2•− in the brain SFO works in concert with other AngII-dependent factors to drive an increase in MAP, as elevated mitochondrial O2•− alone, either in the SFO or peripheral tissues, failed to raise baseline blood pressure.

Intracellular ROS scavenging and antioxidant enzyme regulating capacities of corn gluten meal-derived antioxidant peptides in HepG2 cells

The objective of this study was to investigate the intracellular reactive oxygen species (ROS) scavenging activities and antioxidant enzyme regulating capacities of corn gluten peptide fractions (CPFs) in HepG2 cells. A cellular antioxidant activity (CAA) assay was used to assess their antioxidant activities and revealed that both CPF1 (molecular weight <1kDa) and CPF2 (molecular weight between 1 and 3kDa) exhibited high cellular antioxidant activities with EC50 values of 2.85±0.19mg/mL and 5.05±0.32mg/mL, respectively. Both CPFs also exhibited cytoprotective effects and intracellular ROS scavenging activities in HepG2 cells subjected to oxidative stress by oxidation with H2O2. In addition, at concentrations of 2.50mg/mL, the CPFs increased the activity levels of superoxide dismutase (SOD), catalase (CAT), and glutathione reductase (GR), as well as the total glutathione (GSH) levels in oxidized HepG2 cells (from 86.54% to 114.14% (CPF1) or 109.72% (CPF2) for SOD activity; from 71.91% to 107.64% (CPF1) or 106.50% (CPF2) for CAT activity; from 70.52% to 103.01% (CPF1) or 104.10% (CPF2) for GR activity; and from 81.39% to 114.00% (CPF1) or 108.82% (CPF2) for total GSH levels). These results suggested that both CPF1 and CPF2 exhibited positive effects on the activities of the intracellular antioxidant enzymes SOD, CAT and GR, as well as on the total GSH levels in HepG2 cells under conditions of oxidative stress. Furthermore, size exclusion gel chromatography and MALDI-TOF/TOF mass spectrometry revealed that the molecular weights of the antioxidant peptides in CPF1 were between 500Da to 900Da, and a novel antioxidant peptide consisting of GLLLPH (Gly-Leu-Leu-Leu-Pro-His) was identified in CPF1.

Effects of nano-TiO2 -LDPE packaging on postharvest quality and antioxidant capacity of strawberry (Fragaria ananassa Duch.) stored at refrigeration temperature.

Nano-TiO2 -low-density polyethylene (NTLDPE) packaging was prepared, and the effects of NTLDPE packaging on quality and antioxidant capacity of strawberry fruits were investigated. With increased barrier properties, NTLDPE packaging quickly formed a relative lower O2 and higher CO2 air composition in comparison with LDPE. It was also more efficient in maintaining the overall quality of strawberry fruit, as reflected by lower decay rate and weight loss, as well as retarding the decrease in firmness and titratable acid. Meanwhile, reactive oxygen species (ROS) including superoxide anion and hydrogen peroxide in NTLDPE-packed fruits were 10.8% and 21.9% lower, respectively. Furthermore, the activities of antioxidant enzymes involved in ROS scavenging in NTLDPE-packed fruits were significantly higher at the later period of storage time. Anthocyanin accumulation was inhibited, whereas ascorbic acid and total phenolics contents were better retained and 1-diphenyl-2-picrylhydrazyl radical scavenging activity was 13.2% higher in NTLDPE-packed fruit by the end of storage. These data indicate that the beneficial effects of NTLDPE packaging on postharvest quality and antioxidant capacity of strawberry are probably associated with the promotion of ROS scavenging and related antioxidant enzyme activities, and NTLDPE packaging together with refrigeration storage is a promising method for strawberry fruit preservation. © 2016 Society of Chemical Industry.

How does resveratrol influence the genesis of some neurodegenerative diseases?

How does resveratrol influence the genesis of some neurodegenerative diseases?

Magnetite nanoparticles induced adaptive mechanisms counteract cell death in human pulmonary fibroblasts

Magnetite nanoparticles (MNP) have attracted great interest for biomedical applications due to their unique chemical and physical properties, but the MNP impact on human health is not fully known. Consequently, our study proposes to highlight the biochemical mechanisms that underline the toxic effects of MNP on a human lung fibroblast cell line (MRC-5). The cytotoxicity generated by MNP in MRC-5 cells was dose and time-dependent. MNP-treated MRC-5 cells accumulated large amount of iron and reactive oxygen species (ROS) and exhibited elevated antioxidant scavenger enzymes. Reduced glutathione (GSH) depletion and enhanced lipid peroxidation (LPO) processes were also observed. The cellular capacity to counteract the oxidative damage was sustained by high levels of heat shock protein 60 (Hsp60), a protein that confers resistance against ROS attack and inhibition of cell death. While significant augmentations in nitric oxide (NO) and prostaglandine E2 (PGE2) levels were detected after 72h of MNP-exposure only, caspase-1 was activated earlier starting with 24h post-treatment. Taken together, our results suggest that MRC-5 cells have the capacity to develop cell protection mechanisms against MNP. Detailed knowledge of the mechanisms induced by MNP in cell culture could be essential for their prospective use in various in vivo biochemical applications.

Effects of ALA on Photosynthesis, Antioxidant Enzyme Activity, and Gene Expression, and Regulation of Proline Accumulation in Tomato Seedlings Under NaCl Stress

This study examined the effects of 5-aminolevulinic acid (ALA) application on photosynthesis, activity and gene expression of key antioxidant enzymes, and on proline accumulation in tomato (Lycopersicon esculentum Mill. ‘Hezuo 903’) seedlings under NaCl stress. NaCl stress significantly decreased the net photosynthetic rates and inhibited the activity of photosystem II, whereas exogenous ALA application significantly restored the net photosynthetic rates, quantum yield of electron transport, and energy conversion efficiency of photosystem II of tomato under NaCl stress. Production of superoxide, hydrogen peroxide, and malondialdehyde strongly increased in response to NaCl stress, and these increases were significantly counteracted by ALA. ALA increased the activity of reactive oxygen species (ROS) scavenging antioxidant enzymes, including superoxide dismutase, catalase, ascorbate peroxidase, and peroxidase, and upregulated the expression of SOD, APX, and POD, genes that encode these enzymes in NaCl-treated plants. ALA simultaneously increased proline accumulation in tomato seedlings under NaCl stress by regulating the expression of genes that encode ALA biosynthetic enzymes and that control proline biosynthesis and metabolism, for example, expression of GluRS and GluTR was downregulated, accompanied by a significant increase in the expression of P5CS and decline in the expression of ProDH. ALA provided protection against NaCl stress by increasing photosynthetic capacity, regulating antioxidant enzyme gene expression and proline accumulation, and decreasing ROS accumulation and lipid peroxidation in tomato.

The Role of Matricaria recutita L. and Asparagus officinalis L. against the Neurotoxicity of Diazinon in Rats

Diazinon (DZN) is an organophosphate insecticide used mainly in agriculture and in sheep dips, and is designed as an irreversible acetylcholine esterase inhibitor [1,2]. It is classified as moderately hazardous class-II organophosphate insecticide [3]. Many systems could be affected by organophosphate intoxication are the immune system, urinary system, reproductive system, pancreas and haematological and biochemical changes [4-8]. In addition, showed that neonatal DZN exposure, at doses below the threshold for cholinesterase inhibition has been lasting effects on emotional responses, with preferential effects on males [9,10]. The microsomal enzymes in the liver oxidize DZN are generating more potent acetylcholinesterase inhibitors, such as diazoxon, hydroxydiazoxon and hydroxydiazinon [11]. Diazinon affects mitochondrial membrane transportation in rat liver [12]. Moreover, it interrupts cytochrome P450 system in human liver [13]. Oxidative stress can also be induced by pesticides, either by the overproduction of free radicals or by alteration in antioxidant defence mechanisms, including detoxification and scavenging enzymes [14]. Oxidative stress has been reported to play an important role in the toxicity of various pesticides, including organochlorines, carbamates and pyrethrods [15,16]. The higher oxidative stress in pesticide sprayers is evidenced by increased concentration of plasma and red blood cell thiobarbituric acid reactive substances (TBARS), changes in antioxidant status, and altered activities of cellular enzymes [17]. Treatment of rats with DZN significantly enhances renal lipid peroxidation, which is accompanied by a decrease in the activities of renal antioxidant enzymes (e.g. catalase (CAT), glutathione peroxidise, glutathione reductase (GSH-R), glucose- 6-phosphate dehydrogenase, glutathione-s-transferase (GST) and depletion in the level of glutathione reduced (GSH). In blood, normal erythrocyte function depends on the intactness of cell membrane, which is the target for many toxic factors, including pesticides. Erythrocyte GSH together with glutathione peroxidase (GSH-Px), GSH-R, GST, gamma-glutamyl transferase (γ-GT), superoxide dismutase (SOD) and CAT efficiently scavenge toxic free radicals and are partly responsible for protecting against lipid peroxidation due to acute/chronic pesticide exposure [18]. There is a relationship between pesticide exposure and the decrease of antioxidant enzymes [19]. Oxidative stress and genotoxic effects of DZN were documented through the changes in total antioxidant capacity (TAC), reduced GSH and oxidative DNA damage [20]. Exposure to low-level of pesticides is known to produce a variety of biochemical and molecular changes, some of which may be responsible for the adverse biological effects reported in human and experimental studies. Many studies have reported that DZN can induce molecular changes and alter gene expression. Jamshidi et al. have found that administration of DZN to rats at doses of 60 mg/ kg significantly decreased expression of glutamate dehydrogenase, the key enzyme of Langerhans islet for the secretion of insulin, gene 18- hour post-administration [21]. Other studies showed that DZN had affected the expression of neurotrophic factors that coordinate neuronal cell differentiation and brain assembly [22]. In addition, Timofeeva et al. found that persisting effect of developmental DZN cholinergic and serotonergic neurotransmitter systems and gene expression as well as behavioural function [9]. Matricaria recutita L. (family Asteraceae, commonly known as German chamomile) is one of the most widely used and welldocumented medicinal plants in the world [23]. Chamomile is also

Induction of systemic resistance and defense-related enzymes in tomato plants using Pseudomonas fluorescens CHAO and salicylic acid against root-knot nematode Meloidogyne javanica

Abstract Root-knot nematodes (Meloidogyne spp.) are the most economically important group of plant parasitic nematodes on many crops worldwide. Resistance-based management is considered as one of the most sound and effective strategies against these pathogens. Plant-mediated systemic resistance against the M. javanica in tomato cv. CALJN3 was triggered using salicylic acid (SA) and Pseudomonas fluorescens CHAO as elicitors. The effect of each elicitor was assayed by (1) the calculation of nematode indices including the number of nematode galls, egg masses and eggs/egg mass; (2) the analysis of changes in the concentration of reactive oxygen species (ROS); and (3) monitoring the activities of their scavenging enzymes viz. superoxide dismutase (SOD), peroxidase (POX), and catalase (CAT). The results indicated that SA/bacterial elicitors induced the removal of high concentrations of the toxic ROS via an increase in the activity of their scavenging antioxidant enzymes, especially that of catalase. Moreover, pre- or post-treatment application of the elicitors significantly reduced the number of galls, egg masses or eggs of M. javanica in infected tomato plants as compared to the control. The results of the present study support the involvement of the elicitor-induced ROS and related scavenging enzymes for stimulating plant defense reactions in a moderately resistant tomato challenged with M. javanica.

Overexpression of copper/zinc superoxide dismutase (SOD1) in the median preoptic nucleus attenuates chronic angiotensin II hypertension in the rat (686.16)

The brain senses circulating levels of AngII via circumventricular organs such as the subfornical organ (SFO), and can adjust sympathetic nervous system output accordingly. Previous lesion studies of either the SFO or the downstream MnPO have shown a diminution of the hypertensive effects of chronic AngII, without providing a clear explanation as to the intracellular signaling pathway(s) involved. Additional studies have reported that overexpressing SOD1, an intracellular superoxide (O2•‐) scavenging antioxidant enzyme, in the SFO attenuates chronic AngII‐induced hypertension. Herein, we tested the hypothesis that overproduction of O2•‐ in the MnPO is an underlying mechanism in the long‐term hypertensive effects of chronic AngII. Adenoviral vectors encoding human SOD1 (AdSOD1) or control vector (AdEmpty) were injected into the MnPO of rats implanted with aortic telemetric transmitters for recording of arterial pressure. After a 3 day control period of saline infusion, rats were intravenously infused with AngII (10 ng/kg/min) for ten days. Rats overexpressing SOD1 (n=4) in the MnPO had a blood pressure increase of only 4+2 mmHg after seven days of AngII infusion while blood pressure rose 20+4 mmHg in AdEmpty‐infected rats (n=6). These results support the hypothesis that production of O2•‐ in the MnPO contributes to the development of chronic AngII‐dependent hypertension.

Methyl jasmonate induced defense responses increase resistance to Fusarium oxysporum f. sp. cubense race 4 in banana

Fusarium wilt, caused by the fungal pathogen Fusarium oxysporum, is a severe banana (Musa spp.) root disease, currently threatening banana production worldwide. Methyl jasmonate (MeJA) has been recognized for its ability to induce systemic defense against various pathogens. In this study, we treated banana plantlets with 1.5mM exogenous MeJA. The effects of treatment on the level of chitinase, β-1,3-glucanase, total phenols (TP), hydrogen peroxide (H2O2), superoxide radicals (O2−), malondialdehyde (MDA), as well as the activities of superoxide dismutase (SOD), peroxidase (POD), polyphenol oxidase (PPO), catalase (CAT) and phenylalanine ammonia-lyase (PAL), plus disease incidence (DI) and disease severity (DS) were investigated. The results demonstrated that MeJA regulated the contents of H2O2 and O2−, and decreased MDA in banana roots. Meanwhile, plantlets treated with MeJA exhibited considerably higher chitinase, β-1,3-glucanase and TP contents, and higher activities of SOD, POD, PPO, CAT and PAL. In addition, MeJA treatment dramatically reduced disease incidence (DI) and disease severity (DS) of banana plants compared to control. The higher activities of scavenger antioxidant enzymes account for the reduction of cellular levels of reactive oxygen species (ROS), which is of vital importance for maintaining cell membrane integrity. The accumulation of pathogenesis-related proteins, chitinases and β-1,3-glucanase, as well as total phenols and PAL activity in the treated roots also indicated that MeJA triggered key enzymes of secondary metabolite biosynthetic pathways, suggesting that MeJA was involved in the activation of a disease-related defense system.

Impact of carboxymethyl cellulose coating enriched with extract of Impatiens balsamina stems on preservation of ‘Newhall’ navel orange

A new approach to the control of postharvest decay, while maintaining fruit quality, has been implemented by the application of extract of Impatiens balsamina L. stems, a commonly used traditional Chinese medicine, amended coatings to ‘Newhall’ navel orange (Citrus sinensis L., Osbeck). After harvest, navel oranges were dipped in amended coating and then the samples were stored at 5°C and 90–95% RH after being dried naturally. The data suggested that the coating treatment, respectively, reduced the decay rate and weight loss of fruit from 10.2% to 6.1% and from 6.33% to 2.91% after 100 days storage, with none deleterious effects on fruit quality such as soluble solids content (SSC), titratable acidity (TA) and asorbic acid content (AsA). Moreover, the activities of scavenger antioxidant and defense enzymes, including peroxidase (POD), superoxide dismutase (SOD), chitinase (CHI) and β-1,3-glucanase (GLU), were also increased by the coating treatment. It indicates that the film may be an effective and safe alternative preservative for navel orange.

Anthocyanins, thiols, and antioxidant scavenging enzymes are involved in Lemna gibba tolerance to arsenic

The influence of arsenic (As) on the growth and the antioxidant system of Lemna gibba L. exposed to five concentrations of As (0.0, 0.25, 0.5, 1.0, and 1.5 mg L−1) was studied. Although As exposure reduced relative growth rate, L. gibba continued to grow even after the high accumulation of this element after five days of exposure. The concentration of the superoxide anion was unaffected by As, whereas an increase of hydrogen peroxide concentrations was observed with the increasing of As concentration. Increasing concentrations of As also increased the enzyme activity of superoxide dismutase, peroxidase, and glutathione reductase and the total and nonprotein thiols, up to 0.5 mg L−1, whereas the anthocyanin content increased constantly with As concentration. Catalase and ascorbate peroxidase activities as well as the content of chloroplastic pigments were reduced in plants exposed to all As concentrations. These results support a major role of anthocyanins, nonprotein thiols, and antioxidant scavenging enzymes in L. gibba tolerance to toxic As concentrations.

Interactive influence of arsenate and selenate on growth and nitrogen metabolism in wheat (Triticum aestivum L.) seedlings

The effect of arsenate and selenate, either alone or in combination, on plant growth and nitrogen metabolism was studied in wheat seedlings. The root-shoot elongation and the biomass production were significantly decreased with increasing arsenate concentrations. Arsenate toxicity severely affected activities of different antioxidant scavenging enzymes and oxidative stress markers in the test seedlings. The activities of nitrate and nitrite reductase were also affected resulting in reduced nitrate and nitrite contents. Glutamine synthetase and glutamate synthase activities were also reduced, whereas the glutamate dehydrogenase activity was substantially increased resulting in an increased accumulation of ammonium contents in the test seedlings. Arsenate treatments also adversely affected the levels of total and soluble nitrogen contents and free amino acid contents. Combined application of arsenate with selenate in the test seedlings showed significant alterations in all parameters tested under the purview of arsenate treatment alone leading to better growth and nitrogen metabolism.