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1.
外源NO对铜胁迫下番茄幼苗根系抗坏血酸谷胱甘肽循环的影响 总被引:4,自引:3,他引:1
采用营养液培养方法,研究外源NO对铜胁迫下番茄(Lycopersicon esculentum Mill.)幼苗根系抗坏血酸(AsA)-谷胱甘肽(GSH)循环中抗氧化物质和抗氧化酶系的影响.结果表明:外施适量NO(硝普钠)可提高铜胁迫下番茄幼苗根系AsA、GSH含量和AsA/DHA(氧化型抗坏血酸)、GSH/GSSG(氧化型谷胱甘肽),降低DHA和GSSG含量.添加100 μmol·L-1 BSO(谷胱甘肽合成酶抑制剂)处理下,外源NO可提高铜胁迫下番茄幼苗根系的AsA含量、AsA/DHA及抗坏血酸酶(AAO)、单脱氢抗坏血酸还原酶(MDHAR)和脱氢抗坏血酸还原酶(DHAR)比活性,降低DHA、GSH、GSSG含量及抗坏血酸过氧化物酶(APX)、谷胱甘肽还原酶(GR)比活性;添加250 μmol·L-1 BSO处理下,外源NO提高了铜胁迫下番茄幼苗根系的AsA、GSH、GSSG含量、AsA/DHA及APX和GR比活性,降低了DHA含量及AAO、DHAR和MDHAR比活性.说明外源NO影响了铜胁迫下番茄根系的AsA-GSH代谢循环,并通过调节AsA/DHA、GSH/GSSG的变化来减轻氧化胁迫,从而缓解铜胁迫对番茄根系的伤害. 相似文献
2.
To elucidate the effect of selenium (Se) on the ascorbate?Cglutathione (ASC?CGSH) cycle under drought stress, the activities of antioxidant enzymes and the levels of molecules involved in ASC?CGSH metabolism were studied in Trifolium repens seedlings subjected to polyethylene glycol (PEG)-induced water deficit alone or combined with 5???M Na2SeO4. Compared to the control, H2O2, thiobarbituric acid reactive substances (TBARS), ascorbate (ASC), dehydroascorbate (DHA), and glutathione disulfide (GSSG) contents increased, whereas a constant content of glutathione (GSH) and decreases in ASC/DHA and GSH/GSSG ratios were observed in the presence of PEG. The activities of ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), and glutathione reductase (GR) were upregulated, except for monodehydroascorbate reductase (MDHAR) activity during PEG-induced water deficit. Se application decreased the contents of H2O2, TBARS, DHA, and GSSG, increased the levels of GSH and ASC, and inhibited the decreases of ASC/DHA and GSH/GSSG ratios. Although it did not affect APX activity significantly, Se addition improved the activities of MDHAR, DHAR, and GR. Furthermore, GR activity showed the highest increase followed by that of DHAR and MDHAR in decreasing order. These data indicated that fluctuations in ASC?CGSH metabolism resulting from Se may have a positive effect on drought stress mitigation, and the regulation in the ASC?CGSH cycle can be attributed mainly to GR and DHAR in PEG?+?Se-treated T. repens seedlings. 相似文献
3.
Seedlings of rice (Oryza sativa L.) cv. Pant-12 grown in sand cultures containing 200 and 400 μM NiSO4, showed a decrease in length and fresh weight of roots and shoots. Nickel was readily taken up by rice seedlings and the
concentration was higher in roots than shoots. Nickel-treated seedlings showed increased rates of superoxide anion (O2
•−
) production, elevated levels of H2O2 and thiobarbituric acid reactive substances (TBARS) demonstrating enhanced lipid peroxidation, and a decline in protein thiol
levels indicative of increased protein oxidation compared to controls. With progressively higher Ni concentrations, non-protein
thiol and ascorbate (AsA) increased, whereas the level of low-molecular-weight thiols (such as glutathione and hydroxyl-methyl
glutathione), the ratio of these thiols to their corresponding disulphides, and the ratio of AsA to dehydroascorbic acid declined
in the seedlings. Among the antioxidant enzymes studied, the activities of all isoforms of superoxide dismutase (Cu-Zn SOD,
Mn SOD and Fe SOD), guaiacol peroxidases (GPX) and ascorbate peroxidase (APX) increased in Ni-treated seedlings, while no
clear alteration in catalase activity was evident. Activity of the ascorbate-glutathione cycle enzymes monodehydroascorbate
reductase (MDHAR), dehydroascorbate reductase (DHAR) and glutathione reductase (GR)—significantly increased in Ni-treated
seedlings. However such increase was apparently insufficient to maintain the intracellular redox balance. Results suggest
that Ni induces oxidative stress in rice plants, resulting in enhanced lipid peroxidation and decline in protein thiol levels,
and that (hydroxyl-methyl) glutathione and AsA in conjunction with Cu-Zn SOD, GPX and APX are involved in stress response. 相似文献
4.
Nader Chaparzadeh Maria Lucia D'Amico Ramazan-Ali Khavari-Nejad Riccardo Izzo Flavia Navari-Izzo 《Plant Physiology and Biochemistry》2004,42(9):695-701
To gain a better insight into long-term salt-induced oxidative stress, some physiological parameters in marigold (Calendula officinalis L.) under 0, 50 and 100 mM NaCl were investigated. Salinity affected most of the considered parameters. High salinity caused reduction in growth parameters, lipid peroxidation and hydrogen peroxide accumulation. Under high salinity stress, a decrease in total glutathione and an increase in total ascorbate (AsA + DHA), accompanied with enhanced glutathione reductase (GR, EC 1.6.4.2) and ascorbate peroxidase (APX, EC 1.11.1.11) activities, were observed in leaves. In addition, salinity induced a decrease in superoxide dismutase (SOD, EC 1.15.1.1) and peroxidase (POX, EC 1.11.1.7) activities. The decrease in dehydroascorbate reductase (DHAR, EC 1.8.5.1) and monodehydroascorbate reductase (MDHAR, EC 1.6.5.4) activities suggests that other mechanisms play a major role in the regeneration of reduced ascorbate. The changes in catalase (CAT, EC 1.11.1.6) activities, both in roots and in leaves, may be important in H2O2 homeostasis. 相似文献
5.
D. Camejo M. C. Martí E. Olmos W. Torres F. Sevilla A. Jiménez 《Biologia Plantarum》2012,56(3):537-544
Alfalfa (Medicago sativa L.) roots were treated with 50 and 100 μg cm−3 of oligogalacturonide (OGA) solutions with a degree of polymerization between 7 and 15. Changes in the activities of superoxide
dismutase (SOD), catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR) and
dehydroascorbate reductase (DHAR) as well as ascorbate (ASC) content were determined in crude extract of alfalfa roots after
30, 60 and 120 min of treatment. An increase in the SOD activity was observed in roots treated with 50 and 100 μg cm−3 OGA, which could be related to its O2
·− scavenging function. As concern H2O2 scavenging, CAT activity was increased in the first 30 min by both OGA concentrations, while POX was a key enzyme at higher
OGA concentration and treatment duration. ASC content firstly increased upon exposure to high OGA concentration, and then
decreased after longer treatment while low OGA concentration had no effect on ASC content. 相似文献
6.
In order to elucidate the response of the ascorbate-glutathione (ASC-GSH) cycle to drought stress, the activities of antioxidant
enzymes and the levels of molecules involved in the ASC-GSH metabolism were studied in Trifolium repens L. seedlings subjected to PEG-induced water deficit. Compared to the control, the contents of H2O2, thiobarbituric acid reactive substances (TBARS), ascorbate (ASC), dehydroascorbate (DHA), and glutathione disulfide (GSSG)
increased in PEG-treated seedlings, whereas the glutathione (GSH) content kept constant during the drought period. Further
more, the ASC/DHA and GSH/GSSG ratios decreased in the presence of PEG. Except for that of monodehydroascorbate reductase
(MDHAR), the activities of ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), and glutathione reductase (GR) were
up-regulated during water deficit, and the increases in APX and DHAR activities were much higher than those in GR activity.
These data indicate that fluctuations in the ASC-GSH metabolism resulted from PEG treatment may have a positive effect on
drought stress mitigation in T. repens. 相似文献
7.
Copper affects the enzymes of the ascorbate-glutathione cycle and its related metabolites in the roots of Phaseolus vulgaris 总被引:5,自引:0,他引:5
Manisha Gupta Ann Cuypers Jaco Vangronsveld & Herman Clijsters 《Physiologia plantarum》1999,106(3):262-267
The involvement of the ascorbate-glutathione cycle in the defence against Cu-induced oxidative stress was studied in the roots of Phaseolus vulgaris L. cv. Limburgse vroege. All the enzymes of this cycle [ascorbate peroxidase (APOD), EC 1.11.1.11; monodehydroascorbate reductase (MDHAR), EC 1.6.5.4; dehydroascorbate reductase (DHAR), EC 1.8.5.1; glutathione reductase (GR), EC 1.6.4.2] were increased, and the total ascorbate and glutathione pools rose after a 15 μ M root Cu treatment. In the first hours after the start of the experiment, the accumulation of dehydroascorbate (DHA), formed as a result of a Cu-mediated direct oxidation of ascorbate (AA), was limited by a non-enzymatic reduction using glutathione (GSH) as the reductant. At 24 h, the enzyme capacities of both DHAR and GR were increased to maintain the redox status of the AA and GSH pools. After 72 h of Cu application, the DHAR capacity was inhibited and MDHAR was responsible for maintaining the AA pool in its reduced form. Although the GR capacity was enhanced after 72 h in the treated plants, the GSSG/GSH ratio was increased. This could be due to direct participation of GSH in the detoxification of Cu through reduction and complexation. 相似文献
8.
The effects of methyl jasmonate (MJ) and salicylic acid (SA) on changes of the activities of major antioxidant enzymes, superoxide anion accumulation (O2
−), ascorbate, total glutathione (TG), malondialdehyde (MDA) content and ginsenoside accumulation were investigated in ginseng roots (Panax ginseng L.) in 4 l (working volume) air lift bioreactors. Single treatment of 200 μM MJ and SA to P. ginseng roots enhanced ginsenoside accumulation compared to the control and harvested 3, 5, 7 and 9 days after treatment. MJ and SA treatment induced an oxidative stress in P. ginseng roots, as shown by an increase in lipid peroxidation due to rise in O2
− accumulation. Activity of superoxide dismutase (SOD) was inhibited in MJ-treated roots, while the activities of monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), SOD, guaiacol peroxidase (G-POD), glutathione peroxidase (GPx) and glutathione reductase (GR) were induced in SA-treated roots. A strong decrease in the activity of catalase (CAT) was obtained in both MJ- and SA-treated roots. Activities of ascorbate peroxidase (APX) and glutathione S transferase (GST) were higher in MJ than SA while the contents of reduced ascorbate (ASC), redox state (ASC/(ASC+DHA)) and TG were higher in SA- than MJ-treated roots while oxidized ascorbate (DHA) decreased in both cases. The result of these analyses suggests that roots are better protected against the O2
− stress, thus mitigating MJ and SA stress. The information obtained in this work is useful for efficient large-scale production of ginsenoside by plant-root cultures. 相似文献
9.
Response of the ascorbate-glutathione cycle to re-aeration following hypoxia in lupine roots. 总被引:1,自引:0,他引:1
Ma?gorzata Garnczarska 《Plant Physiology and Biochemistry》2005,43(6):583-590
The response of the enzymes and metabolites of the ascorbate-glutathione pathway to oxidative stress caused by re-aeration following hypoxia was studied in roots of hydroponically grown lupine (Lupinus luteus L. cv. Juno) seedlings. Lupine roots were deprived of oxygen by subjecting them to hypoxia for 48 and 72 h and then re-aerated for up to 4 h. An increased content of total ascorbate was observed in lupine roots immediately after hypoxia, whereas total glutathione level decreased. However, a significant increase in the reduced forms of both metabolites was found directly after hypoxia. Re-admission of oxygen caused the decrease of the ratios of reduced to oxidized forms of ascorbate and glutathione, indicating oxidative stress. While monodehydroascorbate reductase (MDHAR, EC 1.6.5.4) activity remained unaltered during re-aeration the increase in activities of ascorbate peroxidase (APX, EC 1.11.1.11) and glutathione reductase (GR, EC 1.6.4.2) was observed 30 min after transfer from hypoxic condition. Dehydroascorbate reductase (DHAR, EC 1.8.5.1) activity approached the control level during a whole re-aeration period. Native gel electrophoresis combined with specific activity staining revealed seven isoforms of APX, five isoforms of GR and three different proteins with DHA reductase activity in roots extracts. However, immediately after hypoxic treatment APX-5 isoform and GR-1 isoform were not observed in roots. This experimental system was also used to investigate superoxide anion level in roots utilizing the superoxide anion-specific indicator dihydroethidium (DHE). Intense DHE-derived fluorescence was found in re-aerated root tips as compared to control roots, indicating that re-aeration induced superoxide anion production in hypoxically pretreated roots. 相似文献
10.
Effects of putrescine (Put) on responses of wheat (Triticum aestivum) seedlings or detached tillers at mid-milky stage to high temperature (HT) stress were investigated. The heat tolerant cv. PBW 343 exhibited higher content of antioxidants and activities of antioxidative enzymes, while lower content of lipid peroxides as compared to the heat-sensitive cv. HD 2329. HT elevated peroxidase (POX) and superoxide dismutase (SOD) activities, while diamine oxidase (DAO) and polyamine oxidase (PAO) activities were reduced in roots, shoots and developing grains. Application of Put under HT further enhanced POX and SOD activities along with increased content of ascorbate and tocophereol in grains. Invariably POX and SOD revealed higher activities in roots while CAT, DAO and PAO activities were higher in shoots. The content of lipid peroxides was increased in roots and shoots of HT stressed seedlings but less in Put-treated cv. PBW 343. 相似文献
11.
《Plant Physiology and Biochemistry》2002,40(6-8):515-520
The presence of enzymes of the ascorbate–glutathione cycle was studied in mitochondria purified from green and red pepper (Capsicum annuum L.) fruits. All four enzymes, ascorbate peroxidase (APX; EC 1.11.1.11), monodehydroascorbate reductase (MDHAR; EC 1.6.5.4), dehydroascorbate reductase (DHAR; EC 1.8.5.1) and glutathione reductase (GR; EC 1.6.4.2) were present in the isolated mitochondria of both fruit ripening stages. The activity of the reductive ascorbate–glutathione cycle enzymes (MDHAR, GR and DHAR) was higher in mitochondria isolated from green than from red fruits, while APX and the antioxidative enzyme superoxide dismutase (SOD; EC 1.15.1.1) were higher in the red fruits. The levels of ascorbate and L-galactono-γ-lactone dehydrogenase (GLDH; EC 1.3.2.3) activity were found to be similar in the mitochondria of both fruits. The higher APX and Mn-SOD specific activities in mitochondria from red fruits might play a role in avoiding the accumulation of any activated oxygen species generated in these mitochondria, and suggests an active role for these enzymes during ripening. 相似文献
12.
Manganese-excess induces oxidative stress,lowers the pool of antioxidants and elevates activities of key antioxidative enzymes in rice seedlings 总被引:1,自引:0,他引:1
Manganese (Mn) is an essential element for plant growth but in excess, specially in acidic soils, it can become phytotoxic.
In order to investigate whether oxidative stress is associated with the expression of Mn toxicity during early seedling establishment
of rice plants, we examined the changes in the level of reactive oxygen species (ROS), oxidative stress induced an alteration
in the level of non-enzymic antioxidants and activities of antioxidative enzymes in rice seedlings grown in sand cultures
containing 3 and 6 mM MnCl2. Mn treatment inhibited growth of rice seedlings, the metal increasingly accumulated in roots and shoots and caused damage
to membranes. Mn treated plants showed increased generation of superoxide anion (O2
.−), elevated levels of H2O2 and thiobarbituric acid reactive substances (TBARS) and decline in protein thiol. The level of nonprotein thiol, however,
increased due to Mn treatment. A decline in contents of reduced ascorbate (AsA) and glutathione (GSH) as well as decline in
ratios of their reduced to oxidize forms was observed in Mn-treated seedlings. The activities of antioxidative enzymes superoxide
dismutase (SOD) and its isoforms Mn SOD, Cu/Zn SOD, Fe SOD as well as guaiacol peroxidase (GPX) increased in the seedlings
due to Mn treatment however, catalase (CAT) activity increased in 10 days old seedlings but it declined by 20 days under Mn
treatment. The enzymes of Halliwell-Asada cycle, ascorbate peroxidase (APX) monodehydoascorbate reductase (MDHAR), dehyroascorbate
reductase (DHAR) and glutathione reductase (GR) increased significantly in Mn treated seedlings over controls. Results suggest
that in rice seedlings excess Mn induces oxidative stress, imbalances the levels of antioxidants and the antioxidative enzymes
SOD, GPX, APX and GR appear to play an important role in scavenging ROS and withstanding oxidative stress induced by Mn. 相似文献
13.
The activities of the ascorbate-glutathione cycle enzymes ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR) and glutathione reductase (GR) and SOD were studied in cell organelles of the cultivated tomato Lycopersicon esculentum (M82) and its wild salt-tolerant related species Lycopersicon pennellii (Lpa). All four enzymes of the ascorbate-glutathione cycle were present in chloroplasts/plastids, mitochondria and peroxisomes of leaf and root cells of both tomato species. In all leaf and root organelles of both species, the activity of MDHAR was similar to, or higher than, that of APX, while the activity of DHAR was one order of magnitude lower than that of MDHAR. Based on these results, it is suggested that in the organelles of both tomato species, ascorbate is regenerated mainly by MDHAR. In both tomato species, GR activity, and to a lesser extent DHAR activity, was found to reside in the soluble fraction of all leaf and root cell organelles, while APX and MDHAR activities were distributed between the membrane and soluble fractions. A higher SOD to APX activity ratio in all Lpa organelles was the major difference between the two tomato species. It is possible that this higher ratio contributes to the inherently better protection of Lpa from salt stress, as was previously reported. 相似文献
14.
Effects of Irradiance and Copper on the Activity of Ascorbate Oxidase in Detached Rice Leaves 总被引:1,自引:0,他引:1
The effects of copper on the activity of ascorbic acid oxidasc (AAO) in detached rice leaves under both light and dark conditions
and in etiolated rice seedlings were investigated. CuSO4 increased AAO activity in detached rice leaves in both light and darkness, however, the induction in darkness was higher
than in the light. In the absence of CuSO4, irradiance (40 μmol m-2 s-1) resulted in a higher activity of AAO in detached rice leaves than dark treatment. Both CuSO4 and CuCl2 increased AAO activity in detached rice leaves, indicating that AAO is activated by Cu. Sulfate salts of Mg, Mn, Zn and Fe
were ineffective in activating AAO in detached leaves. CuSO4 was also observed to increase AAO activity in the roots but not in shoots of etiolated rice seedlings.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
15.
Z. Zhang X. X. Chang L. Zhang J. M. Li X. H. Hu 《Russian Journal of Plant Physiology》2016,63(4):461-468
The purpose of this study was to elucidate whether exogenous spermidine (Spd) protection of tomato (Solanum lycopersicum L.) seedlings under salinity-alkalinity stress is associated with antioxidant enzymes in the chloroplast. The effects of exogenous Spd on antioxidant enzyme activity and antioxidant content in the chloroplast were evaluated in seedlings of salt-sensitive ecotype (Zhongza 9) grown in a 75 mM salinity-alkalinity solution, with or without 0.25 mM Spd foliar spraying. Results showed that salinity-alkalinity stress increased MDA content, superoxide anion O2?- generation rate, superoxide dismutase (SOD), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR) activities and ratio of AsA/DHA and reduced contents of ascorbate (AsA), dehydroascorbate (DHA), AsA+DHA, glutathione (GSH), oxidized glutathione (GSSG), GSH+GSSG, dehydroascorbate reductase (DHAR) activity and ratio of GSH/GSSG in chloroplasts. The exogenous Spd application combined with salinity-alkalinity stress decreased the O2?- generation rate and MDA content compared to salinity-alkalinity stress alone. The exogenous Spd also increased AsA-GSH cycle components and increased all antioxidant enzyme activities in most cases. Therefore, exogenous Spd alleviates salinity-alkalinity stress damage using antioxidant enzymes and non-enzymatic systems in chloroplasts. 相似文献
16.
Yongqing Yan Chenhui Pan Yuling Du Danyang Li Wei Liu 《Physiology and Molecular Biology of Plants》2018,24(4):577-589
The effect of 0.5–1.5 mM salicylic acid (SA) on modulating reactive oxygen species metabolism and ascorbate–glutathione cycle in NaCl-stressed Nitraria tangutorum seedlings was investigated. The individual plant fresh weight (PFW) and plant dry weight (PDW) significantly increased under 100 mM NaCl while remained unchanged or decreased under 200–400 mM NaCl compared to the control. Superoxide anion (O 2 ·? ), hydrogen peroxide (H2O2), thiobarbituric acid reactive substances (TBARS), reduced ascorbate (AsA), dehydroascorbate (DHA), reduced glutathione (GSH) and oxidized glutathione (GSSG) increased whereas the ratios of AsA/DHA and GSH/GSSG decreased under varied NaCl treatments. Ascorbate peroxidase (APX) and glutathione reductase (GR) activities were enhanced while dehydroascorbate reductase (DHAR) and monodehydroascorbate reductase (MDHAR) activities remained unvaried under 100–400 mM NaCl stresses. In addition, exogenous SA further increased PFW, PDW and root/shoot ratio. SA effectively diminished O 2 ·? accumulation. H2O2 and TBARS decreased under 0.5 and 1.0 mM SA treatments compared to those without SA. 0.5 mM of SA increased while 1.0 and 1.5 mM SA decreased APX activities. DHAR activities were elevated by 0.5 and 1.0 mM SA but not by 1.5 mM SA. MDHAR and GR activities kept constant or significantly increased at varying SA concentrations. Under SA treatments, AsA and GSH contents further increased, DHA and GSSG levels remained unaltered, while the decreases in AsA/DHA and GSH/GSSG ratios were inhibited. The above results demonstrated that the enhanced tolerance of N. tangutorum seedlings conferred by SA could be attributed mainly to the elevated GR and DHAR activities as well as the increased AsA/DHA and GSH/GSSG ratios. 相似文献
17.
Chokri Hafsi María C. Romero-Puertas Luis A. del Río Chedly Abdelly Luisa M. Sandalio 《Acta Physiologiae Plantarum》2011,33(1):193-202
The objective of the present study was to determine the influence of potassium deprivation on the halophyte species Hordeum maritimum grown in hydroponics for 2 weeks. Treatments were with potassium (+K) or without potassium (−K). Growth, water status, mineral
nutrition, parameters of oxidative stress [malondialdehyde (MDA), carbonyl groups (C=O), and hydrogen peroxide concentration
(H2O2) contents], antioxidant enzyme activities [superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6), guaiacol
peroxidase (GPX, EC 1.11.1.7), ascorbate peroxidase (APX, EC 1.11.1.11), monodehydroascorbate peroxidase (MDHAR, EC 1.6.5.4),
dehydroascorbate peroxidase (DHAR, EC 1.8.5.1), and glutathione reductase (GR, EC 1.6.4.2)], and antioxidant molecules [ascorbate
(ASC), and glutathione (GSH)] were determined. Results showed that the growth of vegetative organs decreased owing to potassium
deficiency with roots (−36%) more affected than shoots (−12%). Water status was only diminished in roots (reduction of 24%).
Potassium deprivation decreased potassium concentration in both organs, this decrease was more pronounced in roots (−81%)
than in shoots (−55%). In contrast to carbonyl groups, MDA content increased owing to potassium deprivation. Except for CAT
activity that remained unaffected; SOD, GPX, APX, GR, MDHAR, and DHAR activities were significantly increased. H2O2 concentration was negatively correlated with the activities of enzymes and the accumulation of non-enzymatic antioxidants
implicated in its detoxification. In conclusion, a cooperative process between the antioxidant systems is important for the
tolerance of H. maritimum to potassium deficiency. 相似文献
18.
Role of the Ascorbate-Glutathione Cycle of Mitochondria and
Peroxisomes in the Senescence of Pea Leaves 总被引:10,自引:0,他引:10 下载免费PDF全文
Ana Jiménez José A. Hernández Gabriela Pastori Luis A. del Río Francisca Sevilla 《Plant physiology》1998,118(4):1327-1335
We investigated the relationship between H2O2 metabolism and the senescence process using soluble fractions, mitochondria, and peroxisomes from senescent pea (Pisum sativum L.) leaves. After 11 d of senescence the activities of Mn-superoxide dismutase, dehydroascorbate reductase (DHAR), and glutathione reductase (GR) present in the matrix, and ascorbate peroxidase (APX) and monodehydroascorbate reductase (MDHAR) activities localized in the mitochondrial membrane, were all substantially decreased in mitochondria. The mitochondrial ascorbate and dehydroascorbate pools were reduced, whereas the oxidized glutathione levels were maintained. In senescent leaves the H2O2 content in isolated mitochondria and the NADH- and succinate-dependent production of superoxide (O2·−) radicals by submitochondrial particles increased significantly. However, in peroxisomes from senescent leaves both membrane-bound APX and MDHAR activities were reduced. In the matrix the DHAR activity was enhanced and the GR activity remained unchanged. As a result of senescence, the reduced and the oxidized glutathione pools were considerably increased in peroxisomes. A large increase in the glutathione pool and DHAR activity were also found in soluble fractions of senescent pea leaves, together with a decrease in GR, APX, and MDHAR activities. The differential response to senescence of the mitochondrial and peroxisomal ascorbate-glutathione cycle suggests that mitochondria could be affected by oxidative damage earlier than peroxisomes, which may participate in the cellular oxidative mechanism of leaf senescence longer than mitochondria. 相似文献
19.
Enhanced stress-tolerance of transgenic tobacco plants expressing a human dehydroascorbate reductase gene 总被引:9,自引:0,他引:9
Kwon SY Choi SM Ahn YO Lee HS Lee HB Park YM Kwak SS 《Journal of plant physiology》2003,160(4):347-353
To analyze the physiological role of dehydroascorbate reductase (DHAR, EC 1.8.5.1) catalyzing the reduction of DHA to ascorbate in environmental stress adaptation, T1 transgenic tobacco (Nicotiana tabacum cv. Xanthi) plants expressing a human DHAR gene in chloroplasts were biochemically characterized and tested for responses to various stresses. Fully expanded leaves of transgenic plants had about 2.29 times higher DHAR activity (units/g fresh wt) than non-transgenic (NT) plants. Interestingly, transgenic plants also showed a 1.43 times higher glutathione reductase activity than NT plants. As a result, the ratio of AsA/DHA was changed from 0.21 to 0.48, even though total ascorbate content was not significantly changed. When tobacco leaf discs were subjected to methyl viologen (MV) at 5 mumol/L and hydrogen peroxide (H2O2) at 200 mmol/L, transgenic plants showed about a 40% and 25% reduction in membrane damage relative to NT plants, respectively. Furthermore, transgenic seedlings showed enhanced tolerance to low temperature (15 degrees C) and NaCl (100 mmol/L) compared to NT plants. These results suggest that a human derived DHAR properly works for the protection against oxidative stress in plants. 相似文献
20.
The investigation aimed at determining the effect of nitric oxide on antioxidant defense system of spring maize (Zea mays L.) genotypes namely, LM 11 (stress susceptible) and CML 32 (stress tolerant), that showed differential tolerance towards heat stress. Seed priming with a NO donor, sodium nitroprusside (SNP) improved seedling growth and induced varied defense mechanisms, under stress conditions. 75 μM SNP improved seedling lengths and their biomasses. It specifically enhanced catalase (CAT) activity in the roots of stressed seedlings of the two genotypes. However, it could induce CAT activity only in LM 11 shoots, under heat stress. It also enhanced peroxidase (POX) activity in CML 32 roots. However, such induction of POX activity with SNP treatment was not observed in LM 11 roots. This showed that NO increased the H2O2 scavenging efficiency of CML 32 genotype by enhancing the cumulative activation of CAT and POX in its roots. However, it did not induce activation of any of the H2O2 detoxifying enzymes in CML 32 shoots which showed that ascorbate–glutathione cycle remained non-operational in shoots of SNP-treated seedlings of the tolerant genotype, under high temperature stress. With seed priming, superoxide dismutase (SOD) activity increased in both the tissues of LM 11 seedlings. The shoots of SNP primed CML 32 seedlings, however, did not show any effect on SOD activity which illustrated that nitric oxide might act as a direct scavenger of superoxide radicals in CML 32 seedlings. SNP decreased the contents of H2O2 and MDA and increased proline content in seedlings of both the genotypes indicating reduced oxidative damage. The results thus showed that nitric oxide might induce different mechanisms of stress tolerance in these maize genotypes. 相似文献