Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.6.3.1 (NADPH oxidase)
11,281 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We analysed pathogenesis-related expression of genes, that are assumed to be involved in ubiquitous plant defence mechanisms like the oxidative burst, the hypersensitive cell death reaction (HR) and formation of localized cell wall appositions (papillae). We carried out comparative northern blot and RT-PCR studies with near-isogenic barley (Hordeum vulgareL. cv. Pallas) lines (NILs) resistant or susceptible to the powdery mildew fungus race A6 (Blumeria graminis f.sp. hordei, BghA6). The NILs carrying one of the R-genes Mla12, Mlg or the mlo mutant allele mlo5 arrest fungal development by cell wall appositions (mlo5) or a HR (Mla12) or both (Mlg). Expression of an aspartate protease gene, an ascorbate peroxidase gene and a newly identified cysteine protease gene was up-regulated after inoculation with BghA6, whereas the constitutive expression-level of a BAS gene, that encodes an alkyl hydroperoxide reductase, was reduced. Expression of a newly identified barley homologue of a mammalian cell death regulator, Bax inhibitor 1, was enhanced after powdery mildew inoculation. An oxalate oxidase-like protein was stronger expressed in NILS expressing penetration resistance. A so far unknown gene that putatively encodes the large subunit of a superoxide generating NADPH oxidases was constitutively expressed in barley leaves and its expression pattern did not change after inoculation. A newly identified barley Rac1 homologue was expressed constitutively, such as the functionally linked NADPH oxidase gene. Gene expression patterns are discussed with regard to defence mechanisms and signal transduction.
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PMID:Differential expression of putative cell death regulator genes in near-isogenic, resistant and susceptible barley lines during interaction with the powdery mildew fungus. 1178 35

The roles of the plasma-membrane (PM) NADPH oxidase in abscisic acid (ABA)- and water stress-induced antioxidant defense were investigated in leaves of maize ( Zea mays L.) seedlings. Treatment by exogenous ABA (100 micro M ABA) or osmotic stress (-0.7 MPa induced by polyethylene glycol) significantly increased the activity of the PM NADPH oxidase, the production of leaf O(2)(-), the activities of several antioxidant enzymes (superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase), and the contents of antioxidant metabolites (ascorbate and reduced glutathione). Pretreatment with three different inhibitors of NADPH oxidase (diphenylene iodonium, imidazole and pyridine) or an inhibitor of ABA biosynthesis (tungstate) reduced the increase in the activity of the PM NADPH oxidase and the production of leaf O(2)(-), and the capacity of antioxidant defense systems mediated by ABA. The inhibitory effects above caused by tungstate were reversed by exogenous ABA. These data indicate that NADPH oxidase is involved in the ABA-induced production of active oxygen species (AOS), and our results depict a minimal chain of events initiated by water stress-induced ABA accumulation, which then triggers the production of AOS by membrane-bound NADPH oxidase, resulting in the induction of antioxidant defense systems against oxidative damage in plants.
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PMID:Involvement of plasma-membrane NADPH oxidase in abscisic acid- and water stress-induced antioxidant defense in leaves of maize seedlings. 1235 63

The interrelationship among water-stress-induced abscisic acid (ABA) accumulation, the generation of reactive oxygen species (ROS), and the activities of several antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) was investigated in leaves of detached maize (Zea mays L.) plants exposed to -0.7 MPa water stress induced by polyethylene glycol (PEG 6000). Time-course analyses of ABA content, the production of ROS, and the activities of antioxidant enzymes in water-stressed leaves showed that a significant increase in the content of ABA preceded that of ROS, which was followed by a marked increase in the activities of these antioxidant enzymes. Pretreatment with an ABA biosynthesis inhibitor, tungstate, significantly suppressed the accumulation of ABA, and also reduced the increased generation of ROS and the up-regulation of these antioxidant enzymes in water-stressed leaves. A mild oxidative stress induced by paraquat, which generates O(2)(-) and then H(2)O(2), resulted in a significant enhancement in the activities of antioxidant enzymes in non-water-stressed leaves. Pretreatment with some ROS scavengers, such as Tiron and dimethylthiourea (DMTU), and an inhibitor of NAD(P)H oxidase, diphenyleneiodonium (DPI), almost completely arrested the increase in ROS and the activities of these antioxidant enzymes induced by water stress or ABA treatment. These data suggest that water stress-induced ABA accumulation triggers the increased generation of ROS, which, in turn, leads to the up-regulation of the antioxidant defence system.
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PMID:Water stress-induced abscisic acid accumulation triggers the increased generation of reactive oxygen species and up-regulates the activities of antioxidant enzymes in maize leaves. 1243 32

The signal interactions between calcium (Ca2+) and reactive oxygen species (ROS) originated from plasma membrane NADPH oxidase in abscisic acid (ABA)-induced antioxidant defence were investigated in leaves of maize (Zea mays L.) seedlings. Treatment with ABA led to significant increases in the activity of plasma membrane NADPH oxidase, the production of leaf O2-, and the activities of several antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and glutathione reductase (GR). However, such increases were blocked by the pretreatment with Ca2+ chelator EGTA or Ca2+ channel blockers La3+ and verapamil, and NADPH oxidase inhibitors such as diphenylene iodonium (DPI), imidazole and pyridine. Treatment with Ca2+ also significantly induced the increases in NADPH oxidase activity, O2- production and the activities of antioxidant enzymes, and the increases were arrested by pretreatment with the NADPH oxidase inhibitors. Treatment with oxidative stress induced by paraquat, which generates O2-, led to the induction of antioxidant defence enzymes, and the up-regulation was suppressed by the pretreatment of Ca2+ chelator and Ca2+ channel blockers. Our data suggest that a cross-talk between Ca2+ and ROS originated from plasma membrane-bound NADPH oxidase is involved in the ABA signal transduction pathway leading to the induction of antioxidant enzyme activity, and Ca2+ functions upstream as well as downstream of ROS production in the signal transduction event in plants.
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PMID:Cross-talk between calcium and reactive oxygen species originated from NADPH oxidase in abscisic acid-induced antioxidant defence in leaves of maize seedlings. 1280 20

Reactive oxygen species (ROS), such as O2- and H2O2, play a key role in plant metabolism, cellular signaling, and defense. In leaf cells, the chloroplast is considered to be a focal point of ROS metabolism. It is a major producer of O2- and H2O2 during photosynthesis, and it contains a large array of ROS-scavenging mechanisms that have been extensively studied. By contrast, the function of the cytosolic ROS-scavenging mechanisms of leaf cells is largely unknown. In this study, we demonstrate that in the absence of the cytosolic H2O2-scavenging enzyme ascorbate peroxidase 1 (APX1), the entire chloroplastic H2O2-scavenging system of Arabidopsis thaliana collapses, H2O2 levels increase, and protein oxidation occurs. We further identify specific proteins oxidized in APX1-deficient plants and characterize the signaling events that ensue in knockout-Apx1 plants in response to a moderate level of light stress. Using a dominant-negative approach, we demonstrate that heat shock transcription factors play a central role in the early sensing of H2O2 stress in plants. Using knockout plants for the NADPH oxidase D protein (knockout-RbohD), we demonstrate that RbohD might be required for ROS signal amplification during light stress. Our study points to a key role for the cytosol in protecting the chloroplast during light stress and provides evidence for cross-compartment protection of thylakoid and stromal/mitochondrial APXs by cytosolic APX1.
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PMID:Cytosolic ascorbate peroxidase 1 is a central component of the reactive oxygen gene network of Arabidopsis. 1560 36

The role of H2O2 in abscisic acid (ABA)-induced rice leaf senescence is investigated. ABA treatment resulted in H2O2 production in rice leaves, which preceded the occurrence of leaf senescence. Dimethylthiourea, a chemical trap for H2O2, was observed to be effective in inhibiting ABA-induced senescence, ABA-increased matondialdehyde (MDA) content, ABA-increased antioxidative enzyme activities (superoxide dismutase, ascorbate peroxidase, glutathione reductase and catalase), and ABA-decreased antioxidant contents (ascorbic acid and reduced glutathione) in rice leaves. Diphenyteneiodonium chloride (DPI) and imidazole (IMD), inhibitors of NADPH oxidase, and KCN and NaN3, inhibitors of peroxidase, prevented ABA-induced H2O2 production, suggesting NADPH oxidase and peroxidase are H2O2-generating enzymes in ABA-treated rice leaves. DPI, IMD, KCN, and NaN3 also inhibited ABA-promoted senescence, ABA-increased MDA contents, ABA-increased antioxidative enzyme activities, and ABA-decreased antioxidants in rice leaves. These results suggest that H2O2 is involved in ABA-induced senescence of rice leaves.
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PMID:Hydrogen peroxide is necessary for abscisic acid-induced senescence of rice leaves. 1565 5

The accumulation of H2O2 by NaCl was observed in the roots of rice seedlings. Treatment with NaCl caused an increase in the activities of ascorbate peroxidase (APX) and glutathione reductase (GR) and the expression of OsAPX and OsGR in rice roots. Exogenously applied H2O2 also enhanced the activities of APX and GR and the expression of OsAPX and OsGR in rice roots. The accumulation of H2O2 in rice roots in response to NaCl was inhibited by the NADPH oxidase inhibitors, diphenyleneiodonium chloride (DPI) and imidazole (IMD). However, DPI, IMD, and dimethylthiourea, a H2O2 trap, did not reduce NaCl-enhanced activities of APX and GR and expression of OsAPX and OsGR. It appears that H2O2 is not involved in the regulation of NaCl-induced APX and GR activities and OsAPX and OsGR expression in rice roots.
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PMID:Expression of ascorbate peroxidase and glutathione reductase in roots of rice seedlings in response to NaCl and H2O2. 1583 81

Two-liquid-phase plant cell cultures employ the use of a partitioning system to redirect extracellular product into a second phase. After the addition of organic solvent, in order to understand the defense system of Taxus cuspidata cells to organic solvent in two-liquid-phase suspension cultures, we investigated cells' antioxidant metabolism. The results showed that T. cuspidata cells responded to oleic acid with oxidative bursts in both intracellular H2O2 and extracellular O2-* production. Inhibition studies with diphenylene iodonium suggested that the key enzyme responsible for oxidative bursts was primarily NADPH oxidase. Investigation of the relationship between reactive oxygen species (ROS) and defense responses induced by oleic acid indicated that 4% (v/v) oleic acid increased the levels of antioxidant enzymes of superoxide dismutase, ascorbate peroxidase, and catalase and the antioxidant capacity of reduced ascorbate and glutathione. However, when oleic acid content reached a critical value (6% [v/v]), no further increase in antioxidant enzymes and antioxidant capacity was observed, indicating that the defense responses played a role in a certain range of oleic acid content, beyond which the overall ROS scavenging machinery was not induced and the peroxidation of membrane lipids emerged.
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PMID:Antioxidant responses to oleic acid in two-liquid-phase suspension cultures of Taxus cuspidata. 1583 59

The histochemical and cytochemical localization of abscisic acid (ABA)-induced H(2)O(2) production in leaves of maize (Zea mays L.) plants were examined, using 3,3-diaminobenzidine (DAB) and CeCl(3) staining, respectively, and the relationship between ABA-induced H(2)O(2) production and ABA-induced subcellular activities of antioxidant enzymes was studied. H(2)O(2) generated in response to ABA treatment was detected within 0.5 h in major veins of the leaves and maximized at about 2-4 h. In mesophyll and bundle sheath cells, ABA-induced H(2)O(2) accumulation was observed only in apoplast, and the greatest accumulation occurred in the walls of mesophyll cells facing large intercellular spaces. Meanwhile, ABA treatment led to a significant increase in the activities of the leaf chloroplastic and cytosolic antioxidant enzymes superoxide dismutase (SOD), ascorbate peroxidase (APX) and glutathione reductase (GR), and pretreatment with the NADPH oxidase inhibitor diphenyleneiodonium (DPI), the O (2) (-) scavenger Tiron and the H(2)O(2) scavenger dimethylthiourea (DMTU) almost completely arrested the increase in the activities of these antioxidant enzymes. Our results indicate that the accumulation of apoplastic H(2)O(2) is involved in the induction of the chloroplastic and cytosolic antioxidant enzymes. Moreover, an oxidative stress induced by paraquat (PQ), which generates O (2) (-) and then H(2)O(2) in chloroplasts, also up-regulated the activities of the chloroplastic and cytosolic antioxidant enzymes, and the up-regulation was blocked by the pretreatment with Tiron and DMTU. These data suggest that H(2)O(2) produced at a specific cellular site could coordinate the activities of antioxidant enzymes in different subcellular compartments.
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PMID:Abscisic acid-induced apoplastic H2O2 accumulation up-regulates the activities of chloroplastic and cytosolic antioxidant enzymes in maize leaves. 1604 74

The mechanism for decarboxylating the carboxyl carbon of glycolate was studied in Euglena gracilis Z, which liberates more than 70% of the carboxyl carbon as CO(2) during glycolate metabolism.In the isolated mitochondria of E. gracilis, glycolate was oxidized to glyoxylate, 25% of which was aminated to glycine, with the remaining unchanged in the presence of glutamate; in the absence of the amino donor, glyoxylate was not changed. Irrespective of the presence or absence of the amino donor, no decarboxylation took place in Euglena mitochondria. In Euglena chloroplasts glyoxylate was actively decarboxylated by the action of hydrogen peroxide generated by the reaction of a Mn(2+)-dependent NADPH oxidase. This enzyme was purified 120-fold over the crude extract and some of its properties studied. Oxidation of one molecule of NADPH was accompanied by the formation of one molecule of H(2)O(2); the NADPH oxidation was not attributable to the action of l-ascorbate peroxidase, the sole peroxidase present in E. gracilis. Specific participation of chloroplasts and mitochondria in glycolate metabolism is discussed.
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PMID:Mechanism of Glyoxylate Decarboxylation in the Glycolate Pathway in Euglena gracilis Z : Participation of Mn-Dependent NADPH Oxidase in Chloroplasts. 1666 5


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