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1.
Salinity stress causes ionic stress (mainly from high Na+ and Cl- levels) and osmotic stress (as a result of inhibition of water uptake by roots and amplified water loss from plant tissue), resulting in cell death and inhibition of growth and ultimately adversely reducing crop productivity. In this report, changes in root nitric oxide content, shoot and root biomass, root H2O2 content, root lipid peroxidation, root cell death, root caspase-like enzymatic activity, root antioxidant enzymatic activity and root ascorbate and glutathione contents/redox states were investigated in maize (Zea mays L. cv Silverking) after long-term (21 d) salt stress (150 mM NaCl) with or without exogenously applied nitric oxide generated from the nitric oxide donor 2,2′-(Hydroxynitrosohydrazano)bis-ethane. In addition to reduced shoot and root biomass, salt stress increased the nitric oxide and H2O2 contents in the maize roots and resulted in elevated lipid peroxidation, caspase-like activity and cell death in the roots. Altered antioxidant enzymatic activities, along with changes in ascorbate and glutathione contents/redox status were observed in the roots in response to salt stress. The detrimental effects of salt stress in the roots were reversed by exogenously applied nitric oxide. These results demonstrate that exogenously applied nitric oxide confers salt stress tolerance in maize by reducing salt stress-induced oxidative stress and caspase-like activity through a process that limits accumulation of reactive oxygen species via enhanced antioxidant enzymatic activity.  相似文献   

2.
Salinity stress is a major factor limiting plant growth and productivity of many crops including oilseed. The present study investigated the identification of salt tolerant mustard genotypes and better understanding the mechanism of salinity tolerance. Salt stresses significantly reduced relative water content (RWC), chlorophyll (Chl) content, K+ and K+ /Na+ ratio, photosynthetic rate (PN), transpiration rate (Tr), stomatal conductance (gs), intercellular CO2 concentration (Ci) and increased the levels of proline (Pro) and lipid peroxidation (MDA) contents, Na+ , superoxide (O2•− ) and hydrogen peroxide (H2O2) in both tolerant and sensitive mustard genotypes. The tolerant genotypes maintained higher Pro and lower MDA content than the salt sensitive genotypes under stress condition. The activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), glutathione peroxidase (GPX), monodehydroascorbate reductase (MDHAR) and dehydroascorbate reductase (DHAR) were increased with increasing salinity in salt tolerant genotypes, BJ-1603, BARI Sarisha-11 and BARI Sarisha-16, but the activities were unchanged in salt sensitive genotype, BARI Sarisha-14. Besides, the increment of ascorbate peroxidase (APX) activity was higher in salt sensitive genotype as compared to tolerant ones. However, the activities of glutathione reductase (GR) and glutathione S-transferase (GST) were increased sharply at stress conditions in tolerant genotypes as compared to sensitive genotype. Higher accumulation of Pro along with improved physiological and biochemical parameters as well as reduced oxidative damage by up-regulation of antioxidant defense system are the mechanisms of salt tolerance in selected mustard genotypes, BJ-1603 and BARI Sarisha-16.  相似文献   

3.
Summary This study provides first-hand information on the salinity and copper-induced oxidative damage and its protection in Anabaena doliolum by the antioxidant defence system. Oxidative damage measured in terms of lipid peroxidation, electrolyte leakage and H2O2 production was induced by different concentrations of NaCl and Cu2+. A greater electrolyte leakage by NaCl than Cu2+ supported the hypothesis of salinity being more injurious than copper. To explore the survival strategies of A. doliolum under NaCl and Cu stress, enzymatic antioxidant activities e.g. superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR) and nonenzymatic antioxidant contents such as glutathione reduced (GSH), ascorbate, α-tocopherol, and carotenoid were measured. A general induction in SOD and APX activities as well as ascorbate and α-tocopherol contents was found under NaCl and Cu2+ stress. In contrast to this, an appreciable decline in GR activity, GSH pool and carotenoid content under Cu2+ and an increase under NaCl stress were observed. CAT activity was completely inhibited at high doses of NaCl but stimulated following Cu2+ treatment. The above results suggest the involvement of APX and CAT in the scavenging of H2O2 under Cu2+ stress. In contrast to this, only APX was involved in H2O2 scavenging under salt stress. Our postulate of Cu2+-mediated antagonism of salt stress can be explained by a conceivable reversion of Na+-induced disturbance of cellular homeostasis by redox active Cu2+.  相似文献   

4.
An experiment was conducted to evaluate the influence of Glomus intraradices colonization on the activity of antioxidant enzymes [superoxide dismutase (SOD), catalase (CAT), peroxidase (PX), ascorbate peroxidase (APX), and glutathione reductase (GR)] and the accumulation of nonenzymatic antioxidants (ascorbic acid, α-tocopherol, glutathione, and carotenoids) in roots and leaves of fenugreek plants subjected to varying degrees of salinity (0, 50, 100, and 200 mM NaCl) at two time intervals (1 and 14 days after saline treatment, DAT). The antioxidative capacity was correlated with oxidative damage in the same tissue. Under salt stress, lipid peroxidation and H2O2 concentration increased with increasing severity and duration of salt stress (DoS). However, the extent of oxidative damage in mycorrhizal plants was less compared to nonmycorrhizal plants. The study reveals that mycorrhiza-mediated attenuation of oxidative stress in fenugreek plants is due to enhanced activity of antioxidant enzymes and higher concentrations of antioxidant molecules. However, the significant effect of G. intraradices colonization on individual antioxidant molecules and enzymes varied with plant tissue, salinity level, and DoS. The significant effect of G. intraradices colonization on antioxidative enzymes was more evident at 1DAT in both leaves and roots, while the concentrations of antioxidant molecules were significantly influenced at 14DAT. It is proposed that AM symbiosis can improve antioxidative defense systems of plants through higher SOD activity in M plants, facilitating rapid dismutation of O2 - to H2O2, and subsequent prevention of H2O2 build-up by higher activities of CAT, APX, and PX. The potential of G. intraradices to ameliorate oxidative stress generated in fenugreek plants by salinity was more evident at higher intensities of salt stress.  相似文献   

5.
Sphaerophysa kotschyana is a Turkish endemic and endangered plant that grows near Salt Lake, in Konya, Turkey. However, little is known about the ability of this plant to generate/remove reactive oxygen species (ROS) or its adaptive biochemical responses to saline environments. After exposure of S. kotschyana to 0, 150, and 300 mM NaCl for 7 and 14 days, we investigated (1) the activities and isozyme compositions of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX), and glutathione reductase (GR); (2) the oxidative stress parameters NADPH oxidase (NOX) activity, lipid peroxidation (MDA), total ascorbate (tAsA) content, and total glutathione content (tGlut); and (3) ROS levels for superoxide anion radical (O 2 ·? ), hydrogen peroxide (H2O2), hydroxyl radicals (OH·), and histochemical staining of O 2 ·? and H2O2. H2O2 content increased after 14 days of salt stress, which was consistent with the results from histochemical staining and NOX activity measurements. In contrast, oxidative stress induced by 150 mM NaCl was more efficiently prevented, as indicated by low malondialdehyde (MDA) levels and especially at 7 days, by increased levels of SOD, POX, APX, and GR. However, at 300 mM NaCl, decreased levels of protective enzymes such as SOD, CAT, POX, and GR, particularly with long-term stress (14 days), resulted in limited ROS scavenging activity and increased MDA levels. Moreover, at 300 mM NaCl, the high H2O2 content caused oxidative damage rather than inducing protective responses against H2O2. These results suggest that S. kotschyana is potentially tolerant to salt-induced damage only at low salt concentrations.  相似文献   

6.
The mechanism of selenium (Se)-induced salt tolerance was studied in moderately sensitive soybean (Glycine max L.) plants. To execute this view, soybean plants were imposed with salt stress (EC 6 dS m−1 ) applying NaCl. In other treatments, Se (0, 25, 50 and 75 µM Na2SeO4) was sprayed as co-application with that level of salt stress. Plant height, stem diameter, leaf area, SPAD value decreased noticeably under salt stress. Altered proline (Pro) level, together with decreased leaf relative water content (RWC) was observed in salt-affected plants. Salt stress resulted in brutal oxidative damage and increased the content of H2O2, MDA level and electrolyte leakage. Exogenous Se spray alleviated oxidative damage through boosting up the antioxidant defense system by increasing the activity of antioxidant enzymes such as catalase (CAT), peroxidase (POD) and glutathione reductase (GR), as well as by improving non-enzymatic antioxidants like glutathione (GSH) and GSH/glutathione disulfide (GSSG). The upregulated antioxidant defense system, restored Pro and leaf RWC, higher SPAD value conferred better growth and development in Se-sprayed salt-affected soybean plants which altogether put forth for the progressive yield contributing parameters and finally, seed yield. Among different doses of Se, soybean plants sprayed with 50 µM Na2SeO4 showed better salt tolerance.  相似文献   

7.
The present study investigates the regulatory role of exogenous selenium (Se) in the antioxidant defense and methylglyoxal (MG) detoxification systems in rapeseed seedlings exposed to salt stress. Twelve-day-old seedlings, grown in Petri dishes, were supplemented with selenium (25 μM Na2SeO4) and salt (100 and 200 mM NaCl) separately and in combination, and further grown for 48 h. The ascorbate (AsA) content of the seedlings decreased significantly with increased salt stress. The amount of reduced glutathione (GSH) and glutathione disulfide (GSSG) increased with an increase in the level of salt stress, while the GSH/GSSG ratio decreased. In addition, the ascorbate peroxidase (APX) and glutathione S-transferase (GST) activity increased significantly with increased salt concentration (both at 100 and 200 mM NaCl), while glutathione peroxidase (GPX) activity increased only at moderate salt stress (100 mM NaCl). Glutathione reductase (GR) activity remained unchanged at 100 mM NaCl, while it was decreased under severe (200 mM NaCl) salt stress. Monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), catalase (CAT), glyoxalase I (Gly I), and glyoxalase II (Gly II) activities decreased upon the imposition of salt stress, whereas a sharp decrease of these activities was observed under severe salt stress (200 mM NaCl). Concomitant increases in the levels of H2O2 and lipid peroxidation (MDA) were also measured. Exogenous Se treatment alone had little effect on the non-enzymatic and enzymatic components. However, further investigation revealed that Se treatment had a synergistic effect: in salt-stressed seedlings, it increased the AsA and GSH contents; GSH/GSSG ratio; and the activities of APX, MDHAR, DHAR, GR, GST, GPX, CAT, Gly I, and Gly II. As a result, addition of Se in salt-stressed seedlings led to a reduction in the levels of H2O2 and MDA as compared to salt stress alone. These results suggest that the exogenous application of Se rendered the plants more tolerant to salt stress-induced oxidative damage by enhancing their antioxidant defense and MG detoxification systems.  相似文献   

8.
 以日本引进的设施专用耐盐茄(Solanum melongena)品种‘Torvum Vigor’为砧木, 栽培茄(S. torvum)品种‘苏崎茄’为接穗, 用营养液栽培, 对80 mmol&;#8226;L–1 Ca(NO3)2胁迫下茄子嫁接苗和自根苗叶片抗坏血酸-谷胱甘肽循环系统中抗氧化酶活性和抗氧化物及H2O2含量进行比较。结果表明, Ca(NO3)2胁迫下茄子幼苗叶片H2O2含量有所增加, 但嫁接苗叶片H2O2含量显著低于自根苗。Ca(NO3)2胁迫下嫁接苗叶片抗氧化酶(APX、DHAR和GR)活性、AsA和GSH再生率、氧化还原力(AsA/DHA值和GSH/GSSG值)均显著高于自根苗。综上所述, Ca(NO3)2胁迫下嫁接苗保持良好的AsA-GSH循环效率, 清除H2O2效率较高, 细胞受氧化损伤程度较轻, 表现出较强的耐盐性。  相似文献   

9.
以2年生葡萄(Vitis vinifera L.)酿酒品种赤霞珠扦插苗为材料,在水培条件下,分别用0、0.05、0.10和0.20mg/L 24-表油菜素内酯(EBR)预处理幼苗,然后进行50mmol/L NaCl胁迫,分别在胁迫6d和12d测定幼苗叶片中超氧阴离子(O_2~)、丙二醛(MDA)、抗氧化物质含量以及相关酶活性,探讨EBR预处理对葡萄幼苗耐盐性的影响。结果表明:与单独盐胁迫处理相比,不同浓度的EBR预处理使盐胁迫葡萄幼苗叶片O_2~和MDA含量显著降低,同时使其抗氧化物质抗坏血酸(AsA)、脱氢抗坏血酸(DHA)、还原型谷胱甘肽(GSH)和氧化型谷胱甘肽(GSSG)含量以及抗坏血酸过氧化物酶(APX)、谷胱甘肽还原酶(GR)、超氧化物歧化酶(SOD)活性显著升高;其中,0.10mg/L EBR预处理的表现最佳,在盐胁迫12d时,其葡萄叶O_2~和MDA含量比单独盐胁迫处理分别显著降低30.5%和22.0%,其叶片相应AsA和GSH的含量较单独盐胁迫处理分别显著提高82.8%和27.9%,且GR、APX和SOD活性分别显著提高7.2%、8.5%和24.0%。研究发现,在盐胁迫条件下,适宜浓度的外源BRs预处理能够显著降低葡萄叶片中活性氧含量,提高抗氧化物质含量和抗氧化酶活性,以促进AsA-GSH循环的快速有效运转,有效减轻植株的过氧化伤害,缓解盐胁迫对葡萄幼苗的伤害,提高葡萄的耐盐性。  相似文献   

10.
《Free radical research》2013,47(8):871-880
Abstract

The antibiotic drug 4,4′-diaminodiphenylsulphone (DDS) is used to treat several dermatologic diseases, including Hansen's disease. This study confirmed the antioxidant nature of DDS in hydrogen peroxide (H2O2)-induced oxidative stress and assessed its role in other apoptotic stresses in human diploid fibroblasts (HDFs). Oxidative stress was effectively reduced by DDS in a dose-dependent manner. Moreover, the oxidative stress-induced increases in the levels of the p53 and p21 proteins were inhibited by pre-treatment with DDS. In addition, H2O2 and DDS increased the level of cytochrome P450 (CYP450) IIE1 in HDFs, implicating a role for DDS in H2O2 scavenging via the activation of CYP450. DDS treatment increased the activity of catalase (CAT), glutathione peroxidase (GPx) and glutathione reductase (GR), as well as the GSH/GSSG ratio, indicating activation of the glutathione system against oxidative stress. However, DDS showed no protective effects on HDFs against other apoptotic stimuli, such as thapsigargin and staurosporine, suggesting that DDS would act only against oxidative stress. Therefore, in addition to its antibiotic function, DDS is a potent antioxidant against H2O2-induced oxidative stress in HDFs.  相似文献   

11.
Many physiological and biochemical plant processes affected by salt stress trigger premature nodule senescence and decrease their ability to fix nitrogen. The objective of this study was to evaluate the role of arbuscular mycorrhiza (AM) in moderating salt-induced premature nodule senescence in Cajanus cajan (L.) Millsp. Greenhouse experiments were conducted in which the plants were exposed to salinity stress of 4, 6, and 8 dSm−1. Various parameters linked to nodule senescence were assessed at 80 days after sowing. Nodulation, leghemoglobin content, and nitrogenase enzyme activity measured as acetylene-reducing activity (ARA) were evaluated. Two groups of antioxidant enzymes were studied: (1) enzymes involved in the detoxification of O2 radicals and H2O2, namely, superoxide dismutase (SOD), catalase (CAT) and peroxidase (POX), and (2) enzymes that are important components of the ascorbate glutathione pathway responsible for the removal of H2O2, namely, glutathione reductase (GR) and ascorbate peroxidase (APOX). Exposure of plants to salinity stress enhanced nodule formation; however, nodule growth suffered remarkably and a marked decline in nodule biomass, relative permeability, and lipid peroxidation was observed. Leghemoglobin content and ARA were reduced under saline conditions. AM significantly improved nodulation, leghemoglobin content, and nitrogenase activity under salt stress. Activities of SOD, CAT, APOX, POX, and GR increased markedly in mycorrhizal-stressed plants. A synthesis of the evidence obtained in this study suggests a correlation between enhanced levels of antioxidant enzyme activities, reduced membrane permeability, reduced lipid peroxidation, and improved nitrogen-fixing efficiency of AM plants under stressed and unstressed conditions. These factors could be responsible for the protective effects of mycorrhiza against stress-induced premature nodule senescence.  相似文献   

12.
In order to investigate the effects of spermidine (Spd) and spermine (Spm) on cadmium stress, the content of chlorophyll, hydrogen peroxide (H2O2), malondialdehyde (MDA), soluble protein and proline, the rate of O2·− generation, and activities of antioxidant enzymes (superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX), and glutathione reductase (GR)) in Potamogeton malaianus Miq. were measured. Exogenous application of Spd or Spm significantly enhanced the level of proline, retarded the loss of chlorophyll, enhanced photosynthesis, decreased the rate of O2·− generation and H2O2 content, and prevented Cd-induced lipid peroxidation. Spd and Spm also effectively maintained the balance of antioxidant enzyme activities under Cd stress; however, GR activity was found to increase only slightly in response to polyamines (PAs). The antioxidant systems, which were modified by PAs, were able to moderate the radical-scavenging system and to lessen in this way the oxidative stress. These results suggest that both Spd and Spm can enhance Cd tolerance of P. malaianus.  相似文献   

13.
Antioxidant responses of shoots and roots of lentil to NaCl-salinity stress   总被引:3,自引:0,他引:3  
The effect of salt stress (100 mM and 200 mM NaCl) on antioxidant responses in shoots and roots of 14-day-old lentil (Lens culinaris M.) seedlings was investigated. Salt stress caused a significant decrease in length, wet-dry weight and an increase in proline content of both shoot and root tissues. In leaf tissues, high salinity treatment resulted in a 4.4 fold increase in H2O2 content which was accompanied by a significant level of lipid peroxidation and an increase in electrolyte leakage. Root tissues were less affected with respect to these parameters. Leaf tissue extracts exhibited four activity bands, of which two were identified as Cu/Zn-SOD and others as Fe-SOD and Mn-SOD. Fe-SOD activity was missing in root extracts. In both tissues Cu/Zn-SOD activity comprised 70–75% of total SOD activity. Salt stress did not cause a significant increase in total SOD activity of leaf tissues but a significant enhancement (88%) was observed in roots mainly due to an enhancement in Cu/ZnSOD isoforms. Compared to leaf tissues a significantly higher constitutive ascorbate peroxidase (APX) and glutathion reductase (GR) activity was observed in root tissues. Upon salt stress no significant change in the activity of APX, catalase (CAT) and GR was observed in root tissues but a higher APX activity was present when compared to leaf tissues. On the other hand, in leaf tissues, with the exception of CAT, salt stress caused significant enhancement in the activity of other antioxidant enzymes. These results suggested that, root tissues of lentil are protected better from NaCl stress induced oxidative damage due to enhanced total SOD activity together with a higher level of APX activity under salinity stress. To our knowledge this is the first report describing antioxidant enzyme activities in lentil.  相似文献   

14.

Background and aims

The effects of salt stress on the salt marsh halophyte Spartina alterniflora have been well documented. However, plant responses to combined salinity and ammonium toxicity and the underlying mechanisms are relatively unknown. The aim of the present investigation was to study the effects of both salinity (0, 200 and 500 mM NaCl) and nitrogen form (NO3 ?, NH4 + or NH4NO3) on S. alterniflora.

Methods

Plants were cultivated in sandy soil under greenhouse conditions for 3 months. At harvest, growth parameters were measured and leaf samples were analysed for oxidative stress parameters (malondialdehyde, MDA; electrolyte leakage, EL; and hydrogen peroxide, H2O2 concentration) and the activity of antioxidant enzymes (glutathione reductase, GR; superoxide dismutase, SOD; catalase, CAT; ascorbate peroxidase, APX and Guaiacol peroxidase, GPX).

Results

In the absence of NaCl, plant growth rate was the highest in the medium containing both nitrogen forms, and the lowest in the medium containing only nitrate. Irrespective of the nitrogen form, plant growth was generally higher at 200 mM NaCl than without salinity. Ammonium-fed plants showed better growth than nitrate-fed plants under high salinity. In the absence of salinity, ammonium-fed plants showed higher SOD, APX, GR, CAT, and GPX activities than nitrate-fed ones. The antioxidant enzymes exhibited higher activity in saline-treated plants. The considerable advantage of NH4 + nutrition to S. alterniflora under saline conditions was associated with high antioxidant enzyme activities, together with low MDA content, EL, and H2O2 concentration.

Conclusion

These data clearly demonstrate that NH4 + is more favourable for the growth of S. alterniflora under high salinity than NO3 ?. It is suggested that NH4 + nutrition improves the plant’s capacity to limit oxidative damage by stimulating the activities of the major antioxidant enzymes.  相似文献   

15.
The effects of single or combined stress of aluminum (Al) and chromium (Cr) on plant growth, root dehydrogenase, oxidative stress and antioxidative enzymes were studied using two barley genotypes differing in Al tolerance in a hydroponic experiment. Al or Cr stress decreased plant growth, lowered root dehydrogenase activity and caused oxidative damage, as characterized by increased MDA and H2O2 contents. Under Al or Cr stress, the activities of antioxidative enzymes, including superoxide dismutase (SOD), peroxidase (POD), ascorbate peroxidase (APX), glutathione reductase (GR) and catalase (CAT), were dramatically increased in plant tissues. Gebeina, an Al-tolerant genotype, had less oxidative damage than Shang 70-119, an Al-sensitive genotype. The extent of oxidative damage induced by Cr varied with the pH of the culture solution, with lower pH values (4.0) being more severe than higher pH values (6.5). The combination of Cr and Al caused a further decrease in plant growth, a decrease in root dehydrogenase activity and an increase in MDA and H2O2 contents as well as the activities of antioxidative enzymes. There was also a marked difference between the two barley genotypes in the extent of increased antioxidative enzyme activity under the Cr and Al stresses.  相似文献   

16.
To investigate whether paraquat (PQ) is involved in regulation of antioxidant enzymes and lipid peroxidation under short-term salt stress, and to elucidate the physiological mechanism of salt stress mitigated by PQ, a cucumber cultivar (cv. Chunguang no. 2) was exposed to 100 mM NaCl for 48 h after pre-treatment with 10 μM PQ for 1 h. When compared to the control, salt stress increased the levels of malonaldehyde (MDA), superoxide radical (O2·−) and hydrogen peroxide (H2O2) and the activities of antioxidant enzymes, such as superoxide dismutase (EC 1.15.1.1), ascorbate peroxidase (EC 1.11.1.11) and glutathione reductase (EC 1.6.4.2) in the cucumber leaves. Under salt conditions, PQ pre-treatment prevented oxidative stress as observed by the decreases in MDA, H2O2 and O2·− that correlated with the increase in antioxidant defenses. We propose that, at low concentrations, the PQ pre-treatment can reduce the salt-induced oxidative damage by increasing the antioxidative mechanisms in cucumber plants.  相似文献   

17.
18.
Polyamine metabolism, as well as spermine (Spm) antioxidant properties, were studied in wheat leaves under Cd2+ or Cu2+ stress. The oxidative damage produced by both metals was evidenced by an increased of thiobarbituric acid reactive substances (TBARS) and a significant decrease in glutathione under both metal treatments. Ascorbate peroxidase (APOX) and glutathione reductase (GR) activities were reduced by both metals to values ranging from 30% to 64% of the control values. Conversely, copper produced a raise in superoxide dismutase activity. The high putrescine (Put) content detected under Cd2+ stress (282% over the control) was induced by the increased activity of both enzymes involved in Put biosynthesis, arginine decarboxylase (ADC) and ornithine decarboxylase (ODC). However, only ODC activity was increased in wheat leaves subjected to Cu2+ stress, leading to a lower Put rise (89% over the controls). Spermidine (Spd) content was not affected by metal treatments, while Spm was significantly reduced. Pretreatment with Spm completely reverted the metals-induced TBARS increase whereas metals-dependent H2O2 deposition on leaf segments (revealed using diaminobenzidine), was considerably reduced in Spm pretreated leaf segments. This polyamine failed to reverse the depletion in APOX activity and glutathione (GSH) content produced by Cd2+ and Cu2+, although it showed an efficient antioxidant behavior in the restoration of GR activity to control values. These results suggest that Spm could be exerting a certain antioxidant function by protecting the tissues from the metals-induced oxidative damage, though this effect was not enough to completely avoid Cd2+ and Cu2+ effect on certain antioxidant enzymes, though the precise mechanism of protection still needs to be elucidated.  相似文献   

19.
Salinity is the major environmental constraint that affects legume productivity by inducing oxidative stress. Individually, both silicon (Si) nutrition and mycorrhization have been reported to alleviate salt stress. However, the mechanisms adopted by both in mediating stress responses are poorly understood. Thus, pot trials were undertaken to evaluate comparative as well as interactive effects of Si and/or arbuscular mycorrhiza (AM) in alleviating NaCl toxicity in modulating oxidative stress and antioxidant defence mechanisms in two Cicer arietinum L. (chickpea) genotypes—HC 3 (salt-tolerant) and CSG 9505 (salt-sensitive). Plants subjected to different NaCl concentrations (0–100 mM) recorded a substantial increase in the rate of superoxide radical (O2 ·?), H2O2, lipoxygenase (LOX) activity and malondialdehyde (MDA) content, which induced leakage of ions and disturbed Ca2+/Na+ ratio in roots and leaves. Individually, Si and AM reduced oxidative burst by strengthening antioxidant enzymatic activities (superoxide dismutase (SOD), catalase (CAT) and guaiacol peroxidase (GPOX)). Si was relatively more efficient in reducing accumulation of stress metabolites, while mycorrhization significantly up-regulated antioxidant machinery and modulated ascorbate-glutathione (ASA-GSH) cycle. Combined applications of Si and AM complemented each other in reducing reactive oxygen species (ROS) build-up by further enhancing the antioxidant defence responses. Magnitude of ROS-mediated oxidative burden was lower in HC 3 which correlated strongly with more effective AM symbiosis, better capacity to accumulate Si and stronger defence response when compared with CSG 9505. Study indicated that Si and/or AM fungal amendments upgraded salt tolerance through a dynamic shift from oxidative destruction towards favourable antioxidant defence system in stressed chickpea plants.  相似文献   

20.
Soil flooding is a seasonal factor that negatively affects plant performance and crop yields. In order to investigate the effects of spermidine (Spd) and spermine (Spm) on the waterlogging stress, it was checked that the content of relative water content (RWC), proline, chlorophyll and malondialdehyde (MDA), net photosynthesis, the rate of hydrogen peroxide (H2O2) and superoxide radicals (O2?) generation and the antioxidant enzyme activities of superoxide dismutase (SOD) (EC 1.15.1.1), catalase (CAT) (EC 1.11.1.6), ascorbate peroxidase (APX) (EC 1.11.1.11) and glutathione reductase (GR) (EC 1.6.4.2) in Welsh onion (Allium fistulosum L) plants. Pretreatment with 2 mM of Spd and Spm effectively maintained the balance of water content in plant leaves and roots under flooding stress. In addition, the data indicate that the protective role of proline should be considered minimal, as its accumulation was found to be inversely correlated with tolerance to stress; it also significantly retarded the loss of chlorophyll, enhanced photosynthesis, decreased the rate of O2? generation and H2O2 content, and prevented flooding-induced lipid peroxidation. Spd and Spm helped to maintain antioxidant enzyme activities under flooding; however, APX activity was found to increase slightly in response to Spm. The antioxidant system, an important component of the water-stress-protective mechanism, can be changed by PAs, which are able to moderate the radical scavenging system and to lessen in this way the oxidative stress. The results suggest that pretreatment with Spd and Spm prevents oxidative damage, and the protective effect of Spd was found to be greater than that of Spm.  相似文献   

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