Induction of Rice Cytosolic Ascorbate Peroxidase mRNA by Oxidative Stress; the Involvement of Hydrogen Peroxide in Oxidative Stress Signalling (original) (raw)
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Journal of Plant Physiology, 2012
Hydrogen peroxide (H 2 O 2) is considered a signal molecule inducing cellular stress. Both heat shock (HS) and Cd can increase H 2 O 2 content. We investigated the involvement of H 2 O 2 in HS-and Cd-mediated changes in the expression of ascorbate peroxidase (APX) and glutathione reductase (GR) in leaves of rice seedlings. HS treatment increased the content of H 2 O 2 before it increased activities of APX and GR in rice leaves. Moreover, HS-induced H 2 O 2 production and APX and GR activities could be counteracted by the NADPH oxidase inhibitors dipehenylene iodonium (DPI) and imidazole (IMD). HS-induced OsAPX2 gene expression was associated with HS-induced APX activity but was not regulated by H 2 O 2. Cd-increased H 2 O 2 content and APX and GR activities were lower with than without HS. Cd did not increase the expression of OsAPX and OsGR without HS treatment. Cd increased H 2 O 2 content by Cd before it increased APX and GR activities without HS. Treatment with DPI and IMD effectively inhibited Cd-induced H 2 O 2 production and APX and GR activities. Moreover, the effects of DPI and IMD could be rescued with H 2 O 2 treatment. H 2 O 2 may be involved in the regulation of HS-and Cd-increased APX and GR activities in leaves of rice seedlings.
Rice Science, 2011
Superoxide dismutase (SOD) and ascorbate peroxidase (APX) play central roles in the pathway for scavenging reactive oxygen species in plants, thereby contributing to the tolerance against abiotic stresses. Here we report the responses of cytosolic SOD (cSOD; sodCc1 and sodCc2) and cytosolic APX (cAPX; OsAPx1 and OsAPx2) genes to oxidative and abiotic stresses in rice. RNA blot analyses revealed that methyl viologen treatment caused a more prominent induction of cAPXs compared with cSODs. Hydrogen peroxide treatment induced cAPXs whereas cSODs were not affected. These results suggest that cAPXs play more important roles in defense against oxidative stress compared with cSODs. It is noted that cSODs and cAPXs showed coordinate response to abscisic acid treatment by which sodCc1 and OsAPx2 were both induced. However, cSODs and cAPXs responded differentially to drought, salt, and chilling stresses, which indicates that cSOD and cAPX genes are expressed differentially in response to oxidative and abiotic stresses in rice.
Plant and Cell Physiology, 1997
The activities of enzymes involved in the antioxidative system are lower in rice {Oryza sativa) seedlings that have been germinated under water than in aerobically grown controls and these activities increase when the submerged seedlings are transferred to air. In this study, we examined the changes in protein levels of enzymes implicated in the ascorbate-dependent antioxidative system, namely, ascorbate peroxidase (APX), monodehydroascorbate reductase (MDAR), and dehydroascorbate reductase (DHAR). We found two isozymes of APX and of MDAR, and one form of DHAR in rice. The isozymes of MDAR and DHAR were distributed ubiquitously in rice tissues, but no APX isozyme was found in dry seeds. The levels of all antioxidative proteins were low in submerged seedlings, but repression of their expression was released by transfer of the seedlings to air. However, the levels of some isozymes rose slowly and gradually, while levels of others rose quickly and then fell again.
Plant physiology, 1993
Photosynthesis of leaf discs from transgenic tobacco plants (Nicotiana tabacum) that express a chimeric gene that encodes chloroplast-localized Cu/Zn superoxide dismutase (SOD+) was protected from oxidative stress caused by exposure to high light intensity and low temperature. Under the same conditions, leaf discs of plants that did not express the pea SOD isoform (SOD-) had substantially lower photosynthetic rates. Young plants of both genotypes were more sensitive to oxidative stress than mature plants, but SOD+ plants retained higher photosynthetic rates than SOD- plants at all developmental stages tested. Not surprisingly, SOD+ plants had approximately 3-fold higher SOD specific activity than SOD- plants. However, SOD+ plants also exhibited a 3- to 4-fold increase in ascorbate peroxidase (APX) specific activity and had a corresponding increase in levels of APX mRNA. Dehydroascorbate reductase and glutathione reductase specific activities were the same in both SOD+ and SOD- plant...
Plant responses to stresses: role of ascorbate peroxidase in the antioxidant protection
Genetics and Molecular Biology, 2012
When plants are exposed to stressful environmental conditions, the production of Reactive Oxygen Species (ROS) increases and can cause significant damage to the cells. Antioxidant defenses, which can detoxify ROS, are present in plants. A major hydrogen peroxide detoxifying system in plant cells is the ascorbate-glutathione cycle, in which, ascorbate peroxidase (APX) enzymes play a key role catalyzing the conversion of H 2 O 2 into H 2 O, using ascorbate as a specific electron donor. Different APX isoforms are present in distinct subcellular compartments, such as chloroplasts, mitochondria, peroxisome, and cytosol. The expression of APX genes is regulated in response to biotic and abiotic stresses as well as during plant development. The APX responses are directly involved in the protection of plant cells against adverse environmental conditions. Furthermore, mutant plants APX genes showed alterations in growth, physiology and antioxidant metabolism revealing those enzymes involvement in the normal plant development.
Physiology and Molecular Biology of Plants, 2013
Extremes of temperature (both heat and chilling) during early inbibitional phase of germination caused disruption of redox-homeostasis by increasing accumulation of reactive oxygen species (superoxide and hydrogen peroxide) and significant reduction of antioxidative defense (assessed in terms of total thiol content and activities of superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase) in germinating tissues of rice (Oryza sativa L., cultivar Ratna). Imbibitional heat and chilling stress also induced oxidative damage to newly assembled membrane system by aggravating membrane lipid peroxidation and protein oxidation [measured in terms of thiobarbituric acid reactive substances (TBARS), free carbonyl content (C 0 O groups) and membrane protein thiol level (MPTL)]. Treatment with standardized low titer hydrogen peroxide during early imbibitional phase of germination caused significant reversal in oxidative damages to the newly assembled membrane system imposed by heat and chilling stress [evident from the data of TBARS, C 0 O, MPTL, ROS accumulation, membrane permeability status, membrane injury index and oxidative stress index] in seedlings of experimental rice cultivar. Imbibitional H 2 O 2 pretreatment also caused up-regulation of antioxidative defense (activities of superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase and total thiol content) in the heat and chilling stress-raised rice seedlings. When the parameters of early growth performances were assessed (in terms of relative growth index, biomass accumulation, relative germination performance, mean daily germination, T 50 value), it clearly exhibited significant improvement of early growth performances of the experimental rice cultivar. The result proposes that an 'inductive pulse' of H 2 O 2 is required to switch on some stress acclimatory metabolism through which plant restores redox homeostasis and prevents or repairs oxidative damages to newly assembled membrane system caused by unfavorable environmental cues during early germination to the rice cultivar Ratna. The importance of mitigating oxidative damages to membrane lipid and protein necessary for post-germinative growth under extremes of temperature is also suggested.
Physiology and Molecular Biology of Plants, 2019
Imbibitional oxidative stress of different magnitude, imposed by treatment with different titer of H 2 O 2 (both elevated, 20 mM and low, 500 lM) to an indica rice cultivar (Oryza sativa L., Cultivar Ratna) caused formation of differential redox cues at the metabolic interface, as evident from significant alteration of ROS/antioxidant ratio, efficacy of ascorbate-glutathione cycle, radical scavenging property, modulation of total thiol content and expression of oxidative membrane protein and lipid damages as biomarkers of oxidative stress. All the redox parameters examined, substantiate the experimental outcome that treatment with elevated concentration of H 2 O 2 caused serious loss of redox homeostasis and germination impairment, whereas low titre H 2 O 2 treatment not only restored redox homeostasis but also improve germination and post-germinative growth. The inductive pulse of H 2 O 2 (500 lM) exhibited significantly better performance of ascorbate-glutathione pathway, which was otherwise down-regulated significantly in 20 mM H 2 O 2 treatmentraised seedlings. A comparison between imbibitional chilling stress-raised experimental rice seedlings with 20 mM H 2 O 2 treated rice seedling revealed similar kind of generation of redox cues and oxidative stress response. Further, imbibitional H 2 O 2 treatments in rice also revealed a dose-dependent regulation of expression of genes of Halliwell-Asada pathway enzymes, which is in consonance with the redox metabolic response of germinating rice seeds. In conclusion, a dose-dependent regulation of H 2 O 2 mediated redox cues and redox regulatory properties during germination in rice are suggested, the knowledge of which may be exploited as a promising seed priming technology.
Planta, 2006
Aerobic organisms evolved a complex antioxidant system, which protect the cells against oxidative damage caused by partially reduced oxygen intermediates, also known as reactive oxygen species. In plants, ascorbate peroxidases (EC, 1.11.1.11) catalyze the conversion of H2O2 to H2O, using ascorbate as the specific electron donor in this enzymatic reaction. Previously, eight APx genes were identified in the rice (Oryza sativa L.) genome through in silico analysis: two cytosolic isoforms, two putative peroxisomal isoforms, and four putative chloroplastic ones. Using gene-specific probes, we confirmed the presence of the eight APx genes in the rice genome by Southern blot hybridization. Transcript accumulation analysis showed specific expression patterns for each member of the APx family according to developmental stage and in response to salt stress, revealing the complexity of the antioxidant system in plants. Finally, the subcellular localization of rice APx isoforms was determined using GFP-fusion proteins in BY-2 tobacco cells. In agreement with the initial prediction, OSAPX3 was localized in the peroxisomes. On the other hand, the OSAPX6-GFP fusion protein was found in mitochondria of the BY-2 cells, in contrast to the chloroplastic location predicted by sequence analysis. Our findings reveal the functional diversity of the rice APx genes and suggest complementation and coordination of the antioxidant defenses in different cellular compartments during development and abiotic stress.
Response of antioxidant systems in oxygen deprived suspension cultures of rice (Oryza sativa L.)
Plant Growth Regulation, 2012
The effect of oxygen deprivation (anoxia) on the antioxidant system in suspension culture of anoxiaintolerant Malaysian rice mutants cells was examined. Abiotic stresses have been reported to adversely affect cell division, damage cellular and organelle membranes. The signaling defense mechanisms, such as molecular and biochemical aspects responding to stress have been proven to be very complex, and still largely untapped. The objective of this study was to determine the potential involvement of activated oxygen species, such as superoxide dismutase, catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase which occur in cells of rice plants exposed to anoxia stress in two Malaysian rice mutants, MR219-4 and MR219-9, and rice cultivar FR13A which is known to be tolerant to anoxia stress during 5-30 days of exposure. The antioxidative enzymes were decreased for MR219-4 and MR219-9 mutants for CAT and APX activities, and increased in FR13A cultivar starting at 20 days in suspension culture compared to that of control. CAT and APX activities were maintained higher in anoxia condition for all mutants and cultivar. These findings suggested that anoxia stress in suspension cultures induced the level of H 2 O 2 to toxic levels.