ascorbic-acid and indoleacetic-acid

An emerging stress of nanomaterials in soil and water is of great concern as it limits crop productivity and affects humans as well. Therefore, it is required to manage this problem. Silicon and plant growth promoting rhizobacteria has gained the engaging role in agriculture as (bio-)fertilizers. However, their role against silver nanoparticles (AgNPs) is still not known. Hence, present study was envisaged to investigate role of Si, PGPR and phytohormone indole acetic acid (IAA) in regulating AgNP stress in Brassica juncea seedlings. The study highlighted the impact of various treatments with respect to overproduction of reactive oxygen species, signaling molecule nitric oxide, oxidative markers like antioxidant enzymes and nonenzymatic components of ascorbate-glutathione pathway. Interestingly, silicon when present with AgNPs enhanced toxicity by reducing growth and mechanistic properties of B. juncea. Moreover, the results highlight the role of PGPR and IAA towards reduction in toxicity by promoting the plant growth under stressed conditions. Treatments AgNP + Si + PGPR/IAA were observed to significantly reduce the stress and enhance plant growth against treatment AgNPs alone. This reversal in toxicity by PGPR and IAA along with Si suggests the idea to formulate and utilize their combination as biofertilizers for eradicating the stress in near future.

Topics: Ascorbic Acid; Bacillus thuringiensis; Glutathione; Indoleacetic Acids; Metal Nanoparticles; Mustard Plant; Nitric Oxide; Rhizome; Silicon; Silver

Toxic impact of cadmium (Cd) on plants is well known which affects their productivity. To mitigate toxic impact of metals such as Cd, exogenous application of phytohormones like indole acetic acid (IAA) has been well recognized in the recent past. But, mechanisms related to the IAA-mediated mitigation of metal toxicity remain elusive. Therefore, in this study, effect of IAA on growth and photosynthetic attributes, nitric oxide, cell viability, reactive oxygen species (ROS) and ascorbate-glutathione cycle (AsA-GSH cycle) was investigated in tomato roots exposed to Cd stress. Cd declined growth and photosynthetic attributes which were accompanied by the excess accumulation of Cd and decreased level of nitric oxide (NO). Among photosynthetic attributes, quantum yield parameters were more sensitive to Cd and these results were in parallel of photosynthetic pigments. However, exogenously applied IAA together with Cd significantly improved level of NO, growth and photosynthetic attributes together with reduced accumulation of Cd. Cd enhanced level of superoxide radical and hydrogen peroxide leading to severe damage to lipids and membranes as indicated by increased level of lipid peroxidation and electrolyte leakage which collectively reduced cell viability of roots. Moreover, components of the AsA-GSH cycle i.e. enzymes (ascorbate peroxidase, monodehydroascorbate reducatse, dehydroascorbate reducatse and glutathione reductase) and metabolites (ascorbate and glutathione) were declined by the Cd. However, addition of IAA with Cd had up-regulated components of the AsA-GSH cycle. Interestingly, application of 2,4,6-triiodobenzoic acid (TIBA, a polar auxin transport inhibitor) diminished growth attributes and its combination with Cd worsened its toxicity and these events were in parallel with decline in NO content and enhancement in Cd accumulation. The results also showed that IAA was also able in mitigating Cd toxicity in tomato roots even in the presence of TIBA. Overall results show the essentiality of IAA in mitigating Cd stress in tomato roots through NO that up-regulates components of the AsA-GSH cycle for balancing ROS and their associated damages and hence much improved growth and photosynthetic attributes were noticed.

Topics: Ascorbic Acid; Cadmium; Free Radical Scavengers; Glutathione; Indoleacetic Acids; Nitric Oxide; Photosynthesis; Plant Roots; Reactive Oxygen Species; Solanum lycopersicum

Endogenous hormones and polyamines (PAs) could interact to regulate growth and tolerance to water stress in white clover. The objective of this study was to investigate whether the alteration of endogenous indole-3-acetic acid (IAA) level affected other hormones level and PAs metabolism contributing to the regulation of tolerance to water stress in white clover. Plants were pretreated with IAA or L-2-aminooxy-3-phenylpropionic acid (L-AOPP, the inhibitor of IAA biosynthesis) for 3 days and then subjected to water-sufficient condition and water stress induced by 15% polyethylene glycol 6000 for 8 days in growth chambers. Exogenous application of IAA significantly increased endogenous IAA, gibberellin (GA), abscisic acid (ABA), and polyamine (PAs) levels, but had no effect on cytokinin content under water stress. The increase in endogenous IAA level enhanced PAs anabolism via the improvement of enzyme activities and transcript level of genes including arginine decarboxylase, ornithine decarboxylase, and S-adenosylmethionine decarboxylase. Exogenous application of IAA also affected PAs catabolism, as manifested by an increase in diamine oxidase and a decrease in polyamine oxidase activities and genes expression. More importantly, the IAA deficiency in white clover decreased endogenous hormone levels (GA, ABA, and PAs) and PAs anabolism along with decline in antioxidant defense and osmotic adjustment (OA). On the contrary, exogenous IAA effectively alleviated stress-induced oxidative damage, growth inhibition, water deficit, and leaf senescence through the maintenance of higher chlorophyll content, OA, and antioxidant defense as well as lower transcript levels of senescence marker genes SAG101 and SAG102 in leaves under water stress. These results indicate that IAA-induced the crosstalk between endogenous hormones and PAs could be involved in the improvement of antioxidant defense and OA conferring tolerance to water stress in white clover.

Topics: Abscisic Acid; Adenosylmethionine Decarboxylase; Ascorbic Acid; Carboxy-Lyases; Dehydration; Gibberellins; Glutathione; Indoleacetic Acids; Malondialdehyde; Ornithine Decarboxylase; Osmotic Pressure; Plant Growth Regulators; Polyamines; Real-Time Polymerase Chain Reaction; Trifolium; Water

In the present study, effect of exogenous indole-3-acetic acid at their different levels (i.e. low; IAAL, 10µM and high; IAAH, 100µM) were studied on growth, oxidative stress biomarkers and antioxidant enzymes (SOD, POD, CAT and GST), and metabolites (AsA and GSH) as well as enzymes (APX, GR and DHAR) of ascorbate-glutathione cycle in Trigonella foenum-graecum L. seedlings grown under cadmium (Cd1, 3mgCd kg(-1) soil and Cd2, 9mgCd kg(-1) soil) stress. Cadmium (Cd) at both doses caused reduction in growth which was correlated with enhanced lipid peroxidation and damage to membrane as a result of excess accumulation of O2(•-) and H2O2. Cd also enhanced the oxidation of AsA and GSH to DHA and GSSG, respectively which give a clear sign of oxidative stress, despite of accelerated activity of enzymatic antioxidants: SOD, CAT, POD, GST as well as APX, DHAR (except in Cd2 stress) and GR. Exogenous application of IAAL resulted further rise in the activities of these enzymes, and maintained the redox status (> ratios: AsA/DHA and GSH/GSSG) of cells. The maintained redox status of cells under IAAL treatment declined the level of ROS in Cd1 and Cd2 treated seedlings thereby alleviated the Cd toxicity and this effect was more pronounced under Cd1 stress. Contrary to this, exogenous IAAH suppressed the activity of DHAR and GR and disturbed the redox status (< ratios: AsA/DHA and GSH/GSSG) of cells, hence excess accumulation of ROS further aggravated the Cd induced damage. Thus, overall results suggest that IAA at low (IAAL) and high (IAAH) doses affected the Cd toxicity differently by regulating the ascorbate-glutathione cycle as well as activity of other antioxidants in Trigonella seedlings.

Topics: Antioxidants; Ascorbic Acid; Cadmium; Glutathione; Hydrogen Peroxide; Indoleacetic Acids; Lipid Peroxidation; Oxidation-Reduction; Oxidative Stress; Plant Growth Regulators; Seedlings; Trigonella; Up-Regulation

Hydrogen gas (H2) is an endogenous gaseous molecule in plants. Although its reputation is as a "biologically inert gas", recent results suggested that H2 has therapeutic antioxidant properties in animals and plays fundamental roles in plant responses to environmental stresses. However, whether H2 regulates root morphological patterns is largely unknown. In this report, hydrogen-rich water (HRW) was used to characterize H2 physiological roles and possible signaling transduction pathways in the promotion of adventitious root (AR) formation in cucumber explants. Our results showed that a 50% concentration of HRW was able to mimic the effect of hemin, an inducer of a carbon monoxide (CO) synthetic enzyme, and heme oxygenase-1 (HO-1), in restoring AR formation in comparison with the inhibition effect conferred by auxin-depletion treatment alone. It was further shown that the inducible effect of HRW could be further blocked by the co-treatment with N-1-naphthylphtalamic acid (NPA; an auxin transport inhibitor). The HRW-induced response, at least partially, was HO-1-dependent. This conclusion was supported by the fact that the exposure of cucumber explants to HRW up-regulates cucumber HO-1 gene expression and its protein levels. HRW-mediated induction of representative target genes related to auxin signaling and AR formation, such as CsDNAJ-1, CsCDPK1/5, CsCDC6, CsAUX22B-like, and CsAUX22D-like, and thereafter AR formation (particularly in the AR length) was differentially sensitive to the HO-1 inhibitor zinc protoporphyrin IX (ZnPP). Above blocking actions were clearly reversed by CO, further confirming that the above response was HO-1/CO-specific. However, the addition of a well-known antioxidant, ascorbic acid (AsA), failed to influence AR formation triggered by HRW, thus ruling out the involvement of redox homeostasis in this process. Together, these results indicated that HRW-induced adventitious rooting is, at least partially, correlated with the HO-1/CO-mediated responses. We also suggested that exogenous HRW treatment on plants might be a good option to induce root organogenesis.

Topics: Ascorbic Acid; Carbon Monoxide; Cucumis sativus; Gene Expression Regulation, Plant; Heme Oxygenase-1; Hemin; Hydrogen; Indoleacetic Acids; Phthalimides; Plant Development; Plant Roots

Objectives This study was focused on the role of indole acetic acid (IAA) in the defense against oxidative stress damage caused by drought in soybean plants and to elucidate whether heme oxygenase-1 (HO-1) and nitric oxide (NO) are involved in this mechanism. IAA is an auxin that participates in many plant processes including oxidative stress defense, but to the best of our knowledge no information is yet available about its possible action in drought stress. Methods To this end, soybean plants were treated with 8% polyethylene glycol (PEG) or 100 µM IAA. To evaluate the behavior of IAA, plants were pretreated with this compound previous to PEG addition. Lipid peroxidation levels (thiobarbituric acid reactive substances (TBARS)), glutathione (GSH) and ascorbate (AS) contents, catalase (CAT), superoxide dismutase (SOD), and guaiacol peroxidase (POD) activities were determined to evaluate oxidative damage. Results Drought treatment (8% PEG) caused a significant increase in TBARS levels as well as a marked decrease in the non-enzymatic (GSH and AS) and enzymatic (CAT, SOD, and POD) antioxidant defense systems. Pre-treatment with IAA prevented the alterations of stress parameters caused by drought, while treatment with IAA alone did not produce changes in TBARS levels, or GSH and AS contents. Moreover, the activities of the classical enzymes involved in the enzymatic defense system (SOD, CAT, and POD) remained similar to control values. Furthermore, this hormone could enhance HO-1 activity (75% with respect to controls), and this increase was positively correlated with protein content as well as gene expression. The direct participation of HO-1 as an antioxidant enzyme was established by performing experiments in the presence of Zn-protoporphyrin IX, a well-known irreversible inhibitor of this enzyme. It was also demonstrated that HO-1 is modulated by NO, as shown by experiments performed in the presence of an NO donor (sodium nitroprusside), an NO scavenger (2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide), or an NO synthesis inhibitor (N-nitro-l-arginine methyl ester, NAME). Discussion It is concluded that IAA is responsible, at least in part, for the protection against oxidative stress caused by drought in soybean plants through the modulation of NO levels which, in turn, enhances HO-1 synthesis and activity.

Topics: Antioxidants; Ascorbic Acid; Droughts; Glutathione; Glycine max; Heme Oxygenase (Decyclizing); Indoleacetic Acids; Lipid Peroxidation; Nitric Oxide; Oxidative Stress; Polyethylene Glycols; Stress, Physiological; Thiobarbituric Acid Reactive Substances

The present investigation determined the effects of epibrassinolide (EBL) on the levels of indole-3-acetic acid (IAA), abscisic acid (ABA), and polyamine (PA) and antioxidant potential of 7-d old Raphanus sativus L. cv. 'Pusa chetki' seedlings grown under Cr (VI) metal stress. Reduced titers of free (0.767 μg g(-1) FW) and bound (0.545 μg g(-1) FW) IAA in Cr (VI) stressed seedlings were observed over untreated control. Supplementations of EBL to Cr (VI) stressed seedlings were able to enhance both free (2.14-5.68 μg g(-1) FW) and bound IAA (2.45-7.78 μg g(-1) FW) concentrations in comparison to Cr (VI) metal treatment alone. Significant rise in free (13.49 μg g(-1) FW) and bound (12.17 μg g(-1) FW) ABA contents were noticed for Cr (VI) stressed seedlings when compared to untreated control. No significant increase in ABA contents were recorded for Cr (VI) stressed seedlings upon supplementation with EBL over Cr (VI) treatment alone. A significant increase in Put (18.40 μg g(-1) FW) and Cad (9.08 μg g(-1) FW) contents were found for 10(-9)M EBL plus Cr (VI) metal treatments when compared to Cr (VI) treatment alone. Spermidine (Spd) contents were found to decline significantly for EBL treatment alone or when supplemented with Cr (VI) treatments over untreated controls and Cr (VI) treatment alone. Antioxidant levels were found to enhance, with glutathione (57.98 mg g(-1) FW), proline (4.97 mg g(-1) FW), glycinebetaine (39.01 μmol mL(-1)), ascorbic acid (3.17 mg g(-1) FW) and phytochelatins (65.69 μmol g(-1) FW) contents noted for EBL supplemented to Cr (VI) metal solution over Cr (VI) treatment alone. Reduced activities of guaiacol peroxidase (0.391 U mg(-1) protein) and catalase (0.221 U mg(-1) protein) and enhanced activities of glutathione reductase (7.14 U mg(-1) protein), superoxide dismutase (15.20 U mg(-1) protein) and ascorbate peroxidase (4.31 U mg(-1) protein) were observed in seedlings treated with EBL plus Cr (VI) over Cr metal treatment alone. Reduced MDA (2.55 μmol g(-1) FW) and H(2)O(2) (33.24 μmol g(-1) FW) contents were recorded for 10(-9)M EBL supplemented to Cr (VI) stress over Cr (VI) treatment alone. Enhancement in free radical scavenging potential as indicated by higher values of 1,1-diphenylpicrylhydrazyl, deoxyribose and reducing power activity assays, and increased levels of phenols and soluble sugars also showed significant influence of EBL in alleviating Cr (VI) stress in radish seedlings.

Topics: Abscisic Acid; Antioxidants; Ascorbate Peroxidases; Ascorbic Acid; Brassinosteroids; Catalase; Cholestanols; Chromium; Glutathione Reductase; Indoleacetic Acids; Malondialdehyde; Oxidative Stress; Peroxidase; Peroxidases; Phytochelatins; Polyamines; Proline; Raphanus; Seedlings; Soil Pollutants; Steroids, Heterocyclic; Superoxide Dismutase

The effects of ascorbic acid (AA) and dehydroascorbic acid (DHA), one of products of the disproportionation of monodehydroascorbate (MDHA) by AA oxidase (AAO, EC 1.10.3.3), on the gravitropic curvature of Arabidopsis roots were characterized by biochemical and genetic approaches. Exogenously applied AA and DHA both stimulated root gravitropic responses in a concentration-dependent fashion. AA also changed the Indole-3-acetic acid (IAA) distribution in the roots after gravistimulation. In an effort to determine the relationship between AA and DHA in the gravitropic response, changes in the amount of reduced AA were evaluated in Arabidopsis under a variety of conditions. The expression level of an AAO gene (AAO1) was increased upon gravistimulation. Brassinolide (BL), indole-3-acetic acid (IAA), and AA also increased the transcript levels of this gene. Root elongation and the gravitropic response were both suppressed in the AA biosynthesis mutant, vtc1, which has a greatly reduced level of total AA. Furthermore, the line of AAO double mutants (aao1-1 X aao3-1, 41-21) showed a reduced gravitropic response and reduced root elongation. Taken together, the results of this study imply that both AA and DHA help to determine the redox environment for the root gravitropic response, but DHA, rather than AA, is a major player in the regulation of the gravitropic response mediated by AA in the roots of Arabidopsis thaliana.

Topics: Aldehyde Oxidase; Arabidopsis; Arabidopsis Proteins; Ascorbic Acid; Brassinosteroids; Dehydroascorbic Acid; Gene Expression Regulation, Plant; Gravitropism; Indoleacetic Acids; Mutation; Nucleotidyltransferases; Plant Roots; Steroids, Heterocyclic

Plant stress responses are a key factor in steering the development of cells, tissues, and organs. However, the stress-induced signal transduction cascades that control localized growth and cell size/differentiation are not well understood. It is reported here that oxidative stress, exerted by paraquat or alloxan, induced localized cell proliferation in intact seedlings, in isolated root segments, and at the single cell level. Analysis of the stress-induced mitotic activity revealed that oxidative stress enhances auxin-dependent growth cycle reactivation. Based on the similarities between responses at plant, tissue, or single cell level, it is hypothesized that a common mechanism of reactive oxygen species enhanced auxin-responsiveness underlies the stress-induced re-orientation of growth, and that stress-induced effects on the protoplast growth cycle are directly relevant in terms of understanding whole plant behaviour.

Topics: Alloxan; Arabidopsis; Ascorbic Acid; Cell Differentiation; Germination; Glutathione; Herbicides; Indoleacetic Acids; Oxidative Stress; Paraquat; Plant Leaves; Plant Roots; Protoplasts; Seedlings; Seeds

The combination of indole-3-acetic acid (IAA) and horseradish peroxidase (HRP) has recently been proposed as a novel cancer therapy. However, the mechanism underlying the cytotoxic effect involved is substantially unknown. Here, we show that IAA/HRP treatment induces apoptosis in G361 human melanoma cells, whereas IAA or HRP alone have no effect. It is known that IAA produces free radicals when oxidized by HRP. Because oxidative stress could induce apoptosis, we measured the production of free radicals at varying concentrations of IAA and HRP. Our results show that IAA/HRP produces free radicals in a dose-dependent manner, which are suppressed by ascorbic acid or (-)-epigallocatechin gallate (EGCG). Furthermore, antioxidants prevent IAA/HRP-induced apoptosis, indicating that the IAA/HRP-produced free radicals play an important role in the apoptotic process. In addition, IAA/HRP was observed to activate p38 mitogen-activated protein (MAP) kinase and c-Jun N-terminal kinase (JNK), which are almost completely blocked by antioxidants. We further investigated the IAA/HRP-mediated apoptotic pathways, and found that IAA/HRP activates caspase-8 and caspase-9, leading to caspase-3 activation and poly(ADP-ribose) polymerase (PARP) cleavage. These events were also blocked by antioxidants, such as ascorbic acid or EGCG. Thus, we propose that IAA/HRP-induced free radicals lead to the apoptosis of human melanoma cells via both death receptor-mediated and mitochondrial apoptotic pathways.

Topics: Antioxidants; Apoptosis; Ascorbic Acid; Caspases; Catechin; Cell Line, Tumor; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; Drug Synergism; Drug Therapy, Combination; Free Radicals; Horseradish Peroxidase; Humans; Indoleacetic Acids; JNK Mitogen-Activated Protein Kinases; Melanoma; Mitochondria; Mitogen-Activated Protein Kinases; Oxidative Stress; p38 Mitogen-Activated Protein Kinases; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerases; Prodrugs; Proteins

Previously, it was shown that indole-3-acetic acid (IAA) is a nontoxic prodrug that forms a radical, toxic to tumor cells when activated by peroxidase. Because of this, IAA and peroxidase conjugated to an antibody specific to an extracelluar tumor antigen are currently in phase II clinical trials. In the following, the prooxidant activities of the radicals formed were compared when IAA or its derivatives were metabolically oxidized by peroxidase/H(2)O(2). In general, it was found that the effectiveness of IAA analogues for catalyzing the cooxidation of ascorbate, NADH, or GSH increased as the IAA derivatives were more readily oxidized by HRP/H(2)O(2). The order of effectiveness of IAA derivatives at cooxidizing NADH, ascorbate, GSH, and hepatocyte GSH was 5MeO-2Me-IAA > 2Me-IAA > 5MeO-IAA > IAA. The rates of NADH and ascorbate cooxidation were faster at pH 7.4 than at pH 6.0, whereas GSH cooxidation was faster at pH 6.0 than at pH 7.4. Furthermore, NADH, ascorbate, and GSH prevented the oxidation of IAA derivatives, which suggested that the indolyl cation radical was responsible for the prooxidant activity. The effectiveness of IAA derivatives in catalyzing lipid peroxidation at pH 7.4 was similar and also correlated with the rate of oxidation of IAA derivatives by HRP-I and the one-electron potential of these compounds. The IAA derivative-induced lipid peroxidation was faster at pH 6.0 than at pH 7.4. IAA derivative effectiveness at catalyzing microsomal and hepatocyte lipid peroxidation or hepatocyte reactive oxygen species formation at pH 6.0 was IAA > 5MeO-2Me-IAA > 2Me-IAA > 5MeO-IAA, but at pH 7.4, it was 5MeO-2Me-IAA > 2Me-IAA > 5MeO-IAA > IAA. Previously, the rate of radical cation decarboxylation to skatole radicals and (skatole) peroxyl radicals was reported to be faster at an acid pH with IAA being more effective than the derivatives. This suggests that IAA skatole and/or (skatole) peroxyl radicals catalyze lipid peroxidation at pH 6.0. Incubation of isolated rat hepatocytes with IAA analogues/H(2)O(2)/peroxidase also resulted in cytotoxicity with 5MeO-2Me-IAA being the most effective at pH 7.4 and IAA being the most effective at pH 6.0. Cytotoxicity was also prevented by antioxidants.

Topics: Animals; Antioxidants; Ascorbic Acid; Catalysis; Free Radicals; Glutathione; Horseradish Peroxidase; Hydrogen Peroxide; Hydrogen-Ion Concentration; Indoleacetic Acids; Models, Chemical; NAD; Oxidation-Reduction; Peroxidase; Rats; Rats, Sprague-Dawley

Tryptamine was degraded by incubation with rat brain homogenate to an unknown product. The reaction was stimulated by the nonionic detergents Triton X-100 and Lubrol PX and less by the zwitterionic detergent 3-[(3-cholamidopropyl)dimethylammonio]1-propanesulfonate (CHAPS). The same results were obtained with pig brain and bovine brain. The monoamine oxidase inhibitor pargyline inhibited the reaction strongly, indicating the participation of the enzyme on the reaction. Addition of 17,000 g supernatant from rat brain homogenate increased the formation effectively whereas phospholipids or chloroform/methanol (7:3) extract from the 17,000 g supernatant showed only little or no effect. Chromatographic and electrophoretic properties as well as the chemical reaction of the product with specific reagents suggest that the compound consists of an indole part and an amino acid part. The product could be identified by fast atom bombardment mass spectrometry and by comparison with the synthetic substance (4R)-2-(3-indolylmethyl)-1,3-thiazolidine-4-carboxylic acid. It is formed by the enzymatic oxidation of tryptamine producing indole-3-acetaldehyde which spontaneously cyclizes with free L-cysteine from the tissue. The results suggest that the reaction of biogenic aldehydes with brain macromolecules may proceed via an analogous reaction.

Topics: Acetaldehyde; Aldehydes; Animals; Ascorbic Acid; Brain; Chromatography, High Pressure Liquid; Ethanol; Female; Hydrogen-Ion Concentration; Indoleacetic Acids; Indoles; Liver; Mass Spectrometry; Octoxynol; Pargyline; Phospholipids; Polidocanol; Polyethylene Glycols; Rats; Rats, Inbred Strains; Tryptamines