Salinity induced oxidative stress and antioxidant system in salt-tolerant and salt-sensitive cultivars of rice (Oryza sativa L.)

Indices of oxidative stress viz., superoxide radical and H₂O₂ content increased in leaves of all the cultivars with the rise in salinity level, the increase was more pronounced and significant in salt-sensitive varieties and non-significant in resistant cultivars. Except for glutathione reductase (GR), basal activities of all other antioxidative enzymes viz. superoxide dismutase (SOD), catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX) and glutathione reductase (GR) were significantly higher in leaves of all the resistant cultivars as compared to the sensitive ones. A differential response of salinity was observed on various enzymatic and non-enzymatic components of antioxidant system in leaves of salt-tolerant and salt-sensitive cultivars of rice (Oryza sativa L.). Activities of superoxide dismutase and glutathione reductase enhanced in all the tolerant cultivar while declined in the sensitive cultivars with increasing salinity from 0 to 100 mM. Salt-stress induced the activities of catalase and peroxidase in all the cultivars but the magnitude of increase was more pronounced in the sensitive cultivars than in the tolerant cultivars. Contrarily, APX activity increased in the salt-sensitive cultivars but showed no significant change in the salt-tolerant cultivars. The amount of ascorbic acid content, reduced glutathione (GSH), reduced/oxidized glutathione (GSSG) ratio was higher in leaves of the tolerant cultivars than that of the sensitive cultivars under saline conditions. It is inferred that leaves of salt-tolerant cultivars tend to attain greater capacity to perform reactions of antioxidative pathway under saline conditions to combat salinity-induced oxidative stress.     

2-hydroxy-3-phenylpropanoic acid suppressed the growth of Alternaria alternata through damaging cell membrane integrity and modulating reactive oxygen species metabolism

Black spot rot caused by Alternaria alternata is one of the major postharvest disease of apple fruit during logistic. This study evaluated in vitro inhibitory effect of 2-hydroxy-3-phenylpropanoic acid (PLA) at various concentrations on A. alternata and the possible mechanisms involved in its action. Results showed that different concentrations of PLA inhibited conidia germination and mycelial growth of A. alternata in vitro, and 1.0 g L⁻¹ was the lowest effective concentration to suppress A. alternata growth. Moreover, PLA significantly reduced relative conductivity and increased malondialdehyde and soluble protein contents. PLA also increased H₂O₂ and dehydroascorbic acid contents, but reduced ascorbic acid content. Additionally, PLA treatment inhibited catalase, ascorbate peroxidase, monodehydroascorbate acid reductase, dehydroascorbic acid reductase and glutathione reductase activities, whereas promoted superoxide dismutase activity. All these findings suggest that the possible mechanisms involved in the inhibitory effect of PLA on A. alternata included damaging the cell membrane integrity to cause electrolyte leakage and destroying reactive oxygen species balance.     

Effect of anoxia and reoxygenation on antioxidant enzyme activities in immortalized brain endothelial cells

Summary The effects of anoxia and reoxygenation on major antioxidant enzyme activities were investigatedin vitro in immortalized rat brain endothelial cells (RBE₄ cells). A sublethal anoxic period of 12 h was assessed for RBE₄ cells using the neutral red uptake test. Anoxia markedly influenced the specific activity of catalase and superoxide dismutase, with no major effect on glutathione peroxidase or glutathione reductase. After 24 h postanoxia, the superoxide dismutase activity modulated by the presence or absence of oxygen returned to control value. Damage and recovery of RBE₄ immortalized rat brain endothelial cells in culture after exposure to free radicals and other oxygen-derived species provides a usefulin vitro model to study anoxia-reoxygenation trauma at the cellular level.     

Longevity and antioxidant enzymes,non-enzymatic antioxidants and oxidative stress in the vertebrate lung: a comparative study

It has been proposed that antioxidants can be longevity determinants in animals. However, no comprehensive study has been conducted to try to relate free radicals with maximum life span. This study compares the lung tissue of various vertebrate species — amphibia, mammals and birds — showing very different and well known maximum life spans and life energy potentials. The lung antioxidant enzymes superoxide dismutase, catalase, Se-dependent and non-Se-dependent glutathione peroxidases, and glutathione reductase showed significantly negative correlations with maximum life span. The same was observed for the lung antioxidants, reduced glutathione and ascorbate. It is concluded that a generalized decrease in tissue antioxidant capacity is a characteristic of longevous species. It is suggested that a low rate of free radical recycling (free-radical generation and scavenging) can be an important factor involved in the evolution of high maximum animal longevities. A low free-radical production could be responsible for a low rate of damage at critical sites such as mitochondrial DNA.Abbreviations CAT catalase - COX cytochrome oxidase - GPx glutathione peroxidase - GR glutathione reductase - GSH reduced glutathione - GSSG oxidized glutathione - LEP life energy potential - MDA malondialdehyde - MLSP maximum life span - MR metabolic rate - MW molecular weight - PO₂ partial pressure of oxygen - SOD superoxide dismutase - VO₂ basal oxygen consumption     

Dicarboximide resistance in field isolates of Alternaria alternata is mediated by a mutation in a two-component histidine kinase gene

Isolates of Alternaria alternata collected from a field site which had previously been treated with the dicarboximide fungicide iprodione were found to demonstrate a high level of resistance to iprodione and the phenylpyrrole fungicide, fludioxonil in plate assays. In order to determine the genetic basis for this fungicide resistance a partial length clone of a two-component histidine kinase (HK) was isolated from genomic DNA of a fungicide-sensitive A. alternata isolate using degenerate primers by PCR. Analysis of the AaHK1 gene structure indicates the presence of six 90 amino acid repeat domains upstream of a kinase domain as found in the homologous HK genes from other fungal species. Comparison of nucleic acid sequences from the fungicide-sensitive and fungicide-resistant A. alternata isolates confirmed the presence of mutations leading to premature termination of the translated HK protein. The possible role of the two-component HK in the development of dicarboximide resistance in A. alternata is discussed.     

Effects of Acifluorfen on Endogenous Antioxidants and Protective Enzymes in Cucumber (Cucumis sativus L.) Cotyledons

The herbicide acifluorfen (2-chloro-4-(trifluoromethyl)phenoxy-2-nitrobenzoate) causes strong photooxidative destruction of pigments and lipids in sensitive plant species. Antioxidants and oxygen radical scavengers slow the bleaching action of the herbicide. The effect of acifluorfen on glutathione and ascorbate levels in cucumber (Cucumis sativus L.) cotyledon discs was investigated to assess the relationship between herbicide activity and endogenous antioxidants. Acifluorfen decreased the levels of glutathione and ascorbate over 50% in discs exposed to less than 1.5 hours of white light (450 microeinsteins per square meter per second). Coincident increases in dehydroascorbate and glutathione disulfide were not observed. Acifluorfen also caused the rapid depletion of ascorbate in far-red light grown plants which were photosynthetically incompetent.

Glutathione reductase, dehydroascorbate reductase, superoxide dismutase, ascorbate oxidase, ascorbate free radical reductase, peroxidase, and catalase activities rapidly decreased in acifluorfen-treated tissue exposed to white light. None of the enzymes were inhibited in vitro by the herbicide. Acifluorfen causes irreversible photooxidative destruction of plant tissue, in part, by depleting endogenous antioxidants and inhibiting the activities of protective enzymes.

     

Enzyme activities associated with oxidative stress in Metarhizium anisopliae during germination, mycelial growth, and conidiation and in response to near-UV irradiation

Metarhizium anisopliae isolates have a wide insect host range, but an impediment to their commercial use as a biocontrol agent of above-ground insects is the high susceptibility of spores to the near-UV present in solar irradiation. To understand stress responses in M. anisopliae, we initiated studies of enzymes that protect against oxidative stress in two strains selected because their spores differed in sensitivity to UV-B. Spores of the more near-UV resistant strain in M. anisopliae 324 displayed different isozyme profiles for catalase-peroxidase, glutathione reductase, and superoxide dismutase when compared with the less resistant strain 2575. A transient loss in activity of catalase-peroxidase and glutathione reductase was observed during germination of the spores, whereas the intensity of isozymes displaying superoxide dismutase did not change as the mycelium developed. Isozyme composition for catalase-peroxidases and glutathione reductase in germlings changed with growth phase. UV-B exposure from lamps reduced the activity of isozymes displaying catalase-peroxidase and glutathione reductase activities in 2575 more than in 324. The major effect of solar UV-A plus UV-B also was a reduction in catalase-peroxidases isozyme level, a finding confirmed by measurement of catalase specific activity. Impaired growth of M. anisopliae after near-UV exposure may be related to reduced abilities to handle oxidative stress.     

Redox imbalance in peripheral blood of type 1 myotonic dystrophy patients

Objectives: The aim of our study was to determine if redox imbalance caused by the activities of antioxidant enzymes existed in erythrocytes of type 1 myotonic dystrophy (DM1) patients.

Methods: The activities of erythrocyte superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase were measured in 30 DM1 patients and 15 healthy controls (HCs). The obtained values were correlated with the Muscular Impairment Rating Scale (MIRS) score and creatine kinase (CK).

Results: Superoxide dismutase and catalase activities were lower in DM1 patients compared to HCs. A positive correlation was found between disease duration and MIRS score as well as with glutathione reductase activity. In DM1 patients, there were positive correlations between catalase, glutathione peroxidase, and glutathione reductase activities. After sub-dividing DM1 patients according to CK levels, superoxide dismutase activity was still statistically different from HCs. However, catalase activity was significantly lower only in DM1 patients with increased CK.

Discussion: Undesirable alterations in antioxidant enzyme activities during DM1 disease progression may result in conditions favoring oxidative stress and changes in metabolism which together could contribute to muscle wasting.     

Contribution of Pathogens to Peach Fruit Rot in Northern Greece and their Sensitivity to Iprodione, Carbendazim, Thiophanate-methyl and Tebuconazole Fungicides

This study identified the main pathogens causing fruit rots of mature peaches in northern Greece, the major peach producing area of Greece. The brown rot pathogen Monilinia laxa was responsible for approximately 70% and 78% of rotted peaches in 2005 and 2006 respectively. Serious damage (up to 5%) was also caused with the fungus Phomopsis amygdali. Other pathogens isolated from rotted peaches at a low percentage were Alternaria alternata, Aspergillus niger, Aspergillus flavus, Botrytis cinerea, Sclerotinia sclerotiorum, Fusarium spp., Colletotrichum gloeosporioides, Rhizopus stolonifer and Gilbertella persicaria. Most fungal isolates originated from the rotted peaches were tested for their sensitivity to the fungicides iprodione, carbendazim, thiophanate methyl and tebuconazole at label recommended concentrations. All fungicides inhibited the growth of M. laxa, A. niger, A. flavus, S. sclerotiorum, P. amygdali and B. cinerea on poisoned agar. Apart from iprodione, all other fungicides inhibited the mycelium growth of the pathogen Fusarium sp. The mycelium growth of Fusarium sp. was significantly less with iprodione than control. Only iprodione and tebuconazole were effective against A. alternata and R. stolonifer. Tebuconazole inhibited the mycelium growth of R. stolonifer, while iprodione reduced significantly in comparison to control. The mycelium growth of the fungus C. gloeosporioides was inhibited by tebuconazole and reduced significantly by the fungicides thiophanate methyl, carbendazim and iprodione. Among all the fungi tested, only M. laxa and B. cinerea isolates were found resistant to benzimidazoles [the EC50 (50% effective concentration) value was 100–200 mg/l and 200–300 mg/l for the largest number of thiophanate methyl‐ and carbendazim‐resistant M. laxa isolates respectively, while the biggest number of B. cinerea thiophanate methyl‐ and carbendazim‐resistant isolates showed EC50 value 200–300 mg/l and 300–400 mg/l, respectively]. However, these strains were sensitive to tebuconazole and iprodione. Therefore, these fungicides can be used as an alternative method to control benzimidazole‐resistant Monilinia and Botrytis isolates.     

Assay of free-radical toxicity and antioxidant effect on the Hep 3B cell line: a test survey using lindane

The content of reduced glutathione and of glutathione disulfide as well as the activities of glutathione reductase, glutathione peroxidase, glutathione S-transferases, catalase and superoxide dismutases were determined in human hepatoma Hep 3B cells in relation to free-radical toxicity in order to appreciate the defense capacities of these cells compared to data on normal hepatocytes. When Hep 3B cells were exposed to lindane, a known inducer of free-radical production, superoxide dismutase activity appeared as the best-adapted cellular parameter for early detection of the resulting free-radical toxicity.Abbreviations AAS atomic absorption spectrometry - CDNB 1-chloro-2,4-dinitrobenzene - DMEM Dulbecco's modified Eagle medium - GPx glutathione peroxidase - G.Red glutathione reductase - GSH reduced glutathione - GSSG glutathione disulfide - GST glutathione S-transferases - Prot proteins - SOD superoxide dismutase     

Effect of natural ageing and antioxidant inhibition on liver antioxidant enzymes,glutathione system,peroxidation, and oxygen consumption inRana perezi

Summary A study of the physiological role of oxygen free radicals in relation to the ageing process was performed using the liver ofRana perezi, an animal with a moderate rate of oxygen consumption and a life span substantially longer than that of laboratory rodents.Among the five different antioxidant enzymes only superoxide dismutase (SOD) showed an age-dependent decrease. Cytochrome oxidase (COX), glutathione status, in vivo and in vitro liver peroxidation, and metabolic rate did not vary as a function of age.Long-term (2.5 months) treatment with aminotriazole and diethyldithiocarbamate depleted catalase (CAT) activity and did not change both glutathione peroxidases (GPx), COX, reduced (GSH) and oxidized (GSSG) glutathione, or metabolic rate. This treatment resulted in great compensatory increases in SOD (to 250–460% of controls) and glutathione reductase (GR) (to 200%) which are possibly responsible for the lack of increase of in vivo and in vitro liver peroxidation and for the absence of changes in survival rate.The comparison of these results with previous data from other species suggests the possibility that decreases in antioxidant capacity in old age are restricted to animal species with high metabolic rates. Nevertheless, ageing can still be due to the continuous presence of small concentrations of O₂ radicals in the tissues throughout life in animals with either high or low metabolic rates, because radical scavenging can not be 100% effective. Compensatory homeostasis among antioxidants seems to be a general phenomenon in different species.Abbreviations AT 3-amino-1,2,4 triazole - CAT catalase - COX cytochrome c oxidase - DDC diethyldithiocarbamate - GPx glutathione peroxidase - GR glutathione reductase - GSH reduced glutathione - GSSG oxidized glutathione - MDA malondialdehyde - SOD superoxide dismutase - TBA-RS thiobarbituric acid-reacting substances - VO ₂ oxygen consumption     

Metabolic bases for differences in sensitivity of two pea cultivars to sulfur dioxide

An oxidative chain reaction of sulfite initiated by the superoxide ion produced in the Mehler reaction has been implicated in the damage of plants exposed to sulfur dioxide. The toxicity of SO₂ may be alleviated by free radical scavenging systems acting to terminate this chain reaction. Hence, the relative sensitivity of plants to SO₂ toxicity could depend on differences in the responses of the levels of antioxidant metabolites and enzymes. The effect of SO₂ exposure on glutathione and ascorbic acid contents, glutathione reductase, and superoxide dismutase activities was assayed in two cultivars (Progress, Nugget) of pea (Pisum sativum L.) in which apparent photosynthesis showed a differential sensitivity to 0.8 microliter per liter SO₂ (R. Alscher, J. L. Bower, W. Zipfel [1987] J Exp Bot 38:99-108). Total and reduced glutathione increased more rapidly and to a greater extent in the insensitive Progress than in the sensitive Nugget, as did glutathione reductase activities. Superoxide dismutase activities increased significantly in Progress, whereas no such change was observed in Nugget as a result of SO₂ exposure. This increase in superoxide dismutase activity was observed at 210 minutes after 0.8 microliter per liter SO₂ concentration had been reached, in marked contrast to the increases in reduced glutathione content and glutathione reductase activity, which were apparent at the 90 minute time point. These data suggest that one basis for the relative insensitivity of the apparent photosynthesis of the pea cultivar Progress to SO₂ is the enhanced response of glutathione reductase, superoxide dismutase activities, and glutathione content.     

Alteration of endogenous glutathione peroxidase, manganese superoxide dismutase, and glutathione transferase activity in cells transfected with a copper-zinc superoxide dismutase expression vector. Explanation for variations in paraquat resistance

Transfection of a human pSV2 (copper-zinc) superoxide dismutase expression vector into murine fibroblasts resulted in stable clones producing increased amounts of copper-zinc superoxide dismutase. A marked increase in endogenous glutathione peroxidase activity (up to 285%) and a smaller increase in glutathione transferase activity (up to 16%) also occurred. Manganese superoxide dismutase activity was decreased in all clones, whereas catalase and NADPH reductase activities were not affected. Alterations in glutathione peroxidase and manganese superoxide dismutase activities correlated with increases in copper-zinc superoxide dismutase activity. Whereas all clones were resistant to paraquat, a direct correlation between copper-zinc superoxide dismutase activity and resistance to paraquat did not exist. In agreement with previous reports clones expressing the highest copper-zinc superoxide dismutase activity did not display the highest resistance to paraquat. However, there was a direct correlation between the increase in glutathione peroxidase activity and paraquat resistance (p less than 0.002).     

Exogenous catechin increases antioxidant enzyme activity and promotes flooding tolerance in tomato (Solanum lycopersicum L.)

We studied the extent to which catechin applied as a soil drench modifies the effects of soil waterlogging on plant growth, the functioning of the free radical scavenging system and on oxidative stress levels. Forty-day-old tomato plants (Solanum lycopersicum L.) were treated with 0 and 2?mM catechin 48 h prior to 5 d waterlogging followed by a 4 d drainage period. Exogenous catechin increased total fresh and dry weight of flooded plants, reduced membrane damage, maintained chlorophyll concentrations, promoted photosynthesis and increased ATP concentration in the leaves, and raised sucrose synthase and alcohol dehydrogenase activities in the roots. Catechin pre-treatment also reduced hydrogen peroxide and superoxide radical concentration and increased various components of the antioxidative system in leaves. Catechin treatment affected superoxide dismutase and catalase activities in close coordination with ascorbate peroxidases and glutathione reductase. Exogenous catechin can markedly reduce the waterlogging injury in leaves and roots of tomato by enhancing free radical scavenging system sufficiently to lower hydrogen peroxide and superoxide concentrations.     

Pro-oxidant and antioxidant processes in gas gland and other tissues of cod (Gadus morhua)

Partial reduction of molecular oxygen produces reactive oxyradicals, including the superoxide anion radical (O _- ² ) and hydroxyl radical (·OH). The gas gland functions under hyperoxic and acidic conditions and therefore is likely to be subjected to enhanced oxidative stress. Aspects of pro- and antioxidant processes in gas gland were compared with other tissues likely to be subject to differing degrees of oxyradical production, viz. liver (site of chemically-mediated oxyradical production), gills and skeletal muscle. Antioxidant enzyme activities (superoxide dismutase, catalase, selenium-dependent and total glutathione peroxidase) per g wet weight were highest in liver and lowest in muscle. Catalase and glutathione peroxidase activies per g wet weight were higher in gills than in gas gland, whereas the reverse was seen for superoxide dismutase. Cytosolic superoxide dismutase activities per mg protein were two- and nine-fold higher in gas gland than in liver and gills. The pH characteristics of the antioxidant enzymes were generally similar in all the tissues. Glutathione, vitamin E and unsaturated (peroxidizable) lipid levels were generally highest in liver followed by gas gland. Lipid peroxidation (malonaldehyde equivalents) was evident in all tissues except gas gland. Hydrogen peroxide and O _- ² were involved in the NAD(P)H-dependent ferric/EDTA-mediated formation of ·OH (as measured by 2-keto-4-methiolbutyrate oxidation) by mitochondrial and postmitochondrial fractions of gas gland. Tissue maximal potentials for ·OH production paralled superoxide dismutase but not catalase or glutathione peroxidase activities. Overall, the results confirm the presence of effective antioxidant defences in gas gland and support previous workers' contentions of a central role for superoxide dismutase in this process.Abbreviations EDTA di-sodium ethylenediaminetetra-acetic acid - G-6-P glucose-6-phosphate - GPX total glutathione peroxidase - GSH reduced glutathione - GSSG oxidised glutathione - GST glutathion-S-transferase - HPLC high performance liquid chromatography - KMBA 2-keto-4-methiolbutyric acid - MOPS 3-[N-morpholino] propane-sulphonic acid - PMS postmitochondrial supernatant - Se-GPX selenium-dependent glutathion peroxidase - SOD superoxide dismutase - TCA trichloroacetic acid     

Antioxidant defences of the apoplast

Summary The apoplast of barley and oat leaves contained superoxide dismutase (SOD), catalase, ascorbate peroxidase, dehydroascorbate reductase, monodehydroascorbate reductase, and glutathione reductase activities. The activities of these enzymes in the apoplastic extracts were greatly modified 24 h after inoculation with the biotrophic fungal pathogenBlumeria graminis. The quantum efficiency of photosystem II, which is related to photosynthetic electron transport flux, was comparable in inoculated and healthy leaves during this period. Apoplastic soluble acid invertase activity was also modified in inoculated leaves. Inoculation-dependent increases in apoplastic SOD activity were observed in all lines. Major bands of SOD activity, observed in apoplastic protein extracts by activity staining of gels following isoelectric focusing, were similar to those observed in whole leaves but two additional minor bands were found in the apoplastic fraction. The apoplastic extracts contained substantial amounts of dehydroascorbate (DHA) but little or no glutathione (GSH). Biotic stress decreased apoplastic ascorbate and DHA but increased apoplastic GSH in resistant lines. The antioxidant cycle enzymes may function to remove apoplastic H₂O₂ with ascorbate and GSH derived from the cytoplasm. DHA and oxidized glutathione may be reduced in the apoplast or returned to the cytosol for rereduction.Abbreviations AA reduced ascorbate - APX ascorbate peroxidase - DHA dehydroascorbate (oxidised ascorbate) - DHAR dehydroascorbate reductase - G6PDH glucose-6-phosphate dehydrogenase - GSH reduced glutathione - GSSG glutathione disulphide - GR glutathione reductase - MDHA monodehydroascorbate - MDHAR monodehydroascorbate reductase - SOD superoxide dismutase     

Protective enzymatic systems against activated oxygen species compared in normal and vitrified shoots of Prunus avium L. L. raised in vitro

Vitrification of shoots of Prunus avium L. L. was induced and expressed in a four week in vitro multiplication cycle simply by replacing agar by gelrite. The first vitrification symptoms were visible from the 7th day on. Enzymatic antioxidants were compared weekly in crude extract of normal (on agar) and vitrifying (on gelrite) shoots. The activity of superoxide dismutase was higher in vitrifying shoots. The other enzymes (gaîacol-peroxidase, catalase, ascorbate peroxidase, mono- and dehydro-ascorbate reductases, glutathione reductase) had lower activities. Increased superoxide dismutase activity might mean hydrogen peroxide accumulation and decreased activities of the other enzymes, deficiency in its detoxification. The question therefore is raised whether the hyperhydric morphological abnormalities result from the accumulation of toxic oxygen forms. Vitrification is often considered as a morphological response to several stresses. Contrary to most plants which adapt themselves to stresses by increasing all the above defence enzymes, in vitro shoots under vitrifying conditions appear unable to react in a similar manner.Abbreviations Apx ascorbate peroxidase - Gpx gaîacol peroxidase - CAT catalase - H₂O₂ hydrogen peroxide - SOD superoxide dismutase - MDHAR monodehydroascorbate reductase - DHAR dehydroascorbate reductase - GR glutathione reductase - MS Murashige and Skoog (1962) - IBA indolebutyric acid - BAP benzyladenine - GA₃ gibberellic acid     

Free radical scavenging activity of Cleome gynandra L. leaves on adjuvant induced arthritis in rats

The generation of free radicals has been implicated in the causation of several diseases of known and unknown etiologies such as, rheumatoid arthritis, diabetes, cancer, etc., and compounds that can scavenge free radicals have great potential in ameliorating these disease processes. The present study was aimed to investigate the possible anti-oxidant potential of Cleome gynandra leaf extract at a dose of 150 mg/kg body weight for 30 days on adjuvant induced arthritis in experimental rats. Oral administration of C. gynandra leaf extract significantly increased the levels of lipid peroxides and activities of catalase, glutathione peroxidase and decreased the levels of reduced glutathione and superoxide dismutase activity in arthritis induced rats. The free radical scavenging activity of the plant was further evidenced by histological observations made on the limb tissue. The presence of biologically active ingredients and vital trace elements in the leaves readily account for free radical scavenging property of C. gynandra. (Mol Cell Biochem 276: 71–80, 2005)     

Catalase activity and sensitivity to the fungicides, iprodione and fludioxonil in Botrytis cinerea

C.C. STEEL. 1996. Specific activities of the enzyme catalase were compared with iprodione and fludioxonil sensitivity in 17 field isolates of Botrytis cinerea . Fludioxonil proved to be potnet inhibitor of both iprodione-sensitive and -resistant isolates. Catalase activity was found to be positively correlated with iprodione resistance ( r = 0.77, P < 0.001) confirming that dicarboximide resistance is mediated by enhanced oxidative protective enzymes. No such correlation was found with fludioxonil suggesting that resistance at the biochemical level differs for the two fungicide groups.     

Influence of salt stress on growth,lipid peroxidation and antioxidative enzyme activity in borage (Borago officinalis L.)

Abstract

The effects of increasing salt concentrations on the growth, electrolyte leakage, lipid peroxidation, and major antioxidant enzyme activities (superoxide dismutase, catalase, ascorbate peroxidase and glutathione reductase) of borage plants were investigated. Plants were grown in half strength of Hoagland nutrient solution added with 0, 25, 50, and 75 mM of NaCl. Most measured parameters were affected by salinity. Increasing salt levels caused a significant reduction in leaf area, stem length, stem diameter, flower number, and dry masses of different organs. Growth of borage plants, in terms of dry weight, was affected. As a consequence of salinity stress, lipid peroxidation and membrane permeability was increased. Antioxidant activity showed an increase in the activity of superoxide dismutase, a non-induced activity of catalase and ascorbate peroxidase, and a slight increase in glutathione reductase activity. The results indicate that borage plants appear to be sensitive to salt stress, since enzymes related to antioxidant enzymatic defense system in treated leaves should be highly active.