Salt Stress Injury Induces Oxidative Alterations and Antioxidative Defence in the Roots of Lemna minor

Lemna minor L. roots were treated with different concentrations of NaCl. Lipid peroxidation was investigated histochemically and biochemically. At higher NaCl concentrations an increase in staining was observed in the root apices as compared to control for lipid peroxidation and loss of membrane integrity as well as an increase in contents of thiobarbituric acid reactive substance and peroxide. Both the non-enzymic antioxidants, ascorbate and glutathione increased with the NaCl concentration in the roots. Whereas an increase in superoxide dismutase, guaiacol peroxidase, and glutathione reductase activities were marked, catalase activity decreased in the roots under NaCl stress. This revised version was published online in July 2006 with corrections to the Cover Date.     

Herbicide Induced Oxidative Stress in Lettuce, Beans, Pea Seeds and Leaves

The effects of different paraquat, alachlor and metolachlor concentrations on superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (GPX) activities and pigment contents in lettuce, bean and pea seeds and leaves were studied. Under paraquat (1.0 and 2.0 M) treatment declined SOD and CAT activities were observed in seeds and undetectable ativity of GPX. Germination of all investigated seeds was completely inhibited. All used concentrations of alachlor and metolachlor inhibited antioxidant enzyme activities in seeds but did not prevent germination and growth. In leaves, lower concentrations of these herbicides increased activities of antioxidant enzymes but at the highest herbicide concentrations (200 M) activities of investigated enzymes declined. The pigment contents the leaves decreased due to alachlor and metolachlor treatment in a concentration dependent manner.     

The effect of NaCl on antioxidant enzyme activities in potato seedlings

The effect of NaCl on the growth and activity of antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX) were investigated in the seedlings of four potato cultivars (Agria, Kennebec; relatively salt tolerant, Diamant and Ajax; relatively salt sensitive). The shoot fresh mass of Agria and Kennebec did not changed at 50 mM NaCl, whereas in Diamant and Ajax it decreased to 50 % of that in the controls. In Agria and Kennebec, SOD activity increased at 50 mM NaCl, but no significant changes observed in Diamant and Ajax. At higher NaCl concentration, SOD activity reduced in all cultivars. CAT and POD activities increased in all cultivars under salt stress. Unlike the other cultivars, in Ajax seedlings, APX activity increased in response to NaCl stress. We also observed new POD and SOD isoenzyme activities and changes in isoenzyme compositions under salt stress. These results suggest that salt-tolerant potato cultivars may have a better protection against reactive oxygen species (ROS) by increasing the activity of antioxidant enzymes (especially SOD) under salt stress.     

Short-term effect of elevated CO2 concentration and high irradiance on the antioxidant enzymes in bean plants

The effect of short-term exposure to elevated CO₂ concentration and high irradiance on the activity of superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidases (GPX) and catalase (CAT), and on the extent of the lipid peroxidation was studied in bean (Phaseolus vulgaris L.) plants. Plants were exposed for 4 d (8 h a day) to irradiance of 100 (LI) or 1000 (HI) μmol m⁻² s⁻¹ at ambient (CA, 350 μmol mol⁻¹) or elevated (CE, 1300 μmol mol⁻¹) CO₂ concentration. Four-day exposure to CE increased the leaf dry mass in HI plants and RuBPC activity and chlorophyll content in LI plants. Total soluble protein content, leaf dry matter and RuBPC activity were higher in HI than in LI plants, although the HI and CE increased the contents of malonyldialdehyde and H₂O₂. Under CA, exposure to HI increased the activity of APX and decreased the total SOD activity. Under CE, HI treatment also activated APX and led to reduction of both, SOD and GPX, enzymes activities. CE considerably reduced the CAT activity at both irradiances, possibly due to suppressed rate of photorespiration under CE conditions.     

Antioxidant enzymes and physiological characteristics in two Jerusalem artichoke cultivars under salt stress

The effects of NaCl stress on the activity of antioxidant enzymes, lipid peroxidation, cell membrane stability, net photosynthetic rate, gas-exchange, and chlorophyll content were investigated in two Jerusalem artichoke cultivars, Dafeng (salt-tolerant) and Wuxi (salt-sensitive), grown under control (nutrient solution) or salt stress (nutrient solution containing 75, 150, and 225 mM NaCl) conditions for 7 days. In leaves of salt-tolerant cv. Dafeng, superoxide dismutase (EC 1.15.1.1), peroxidase (EC 1.11.1.7), and catalase (EC 1.11.1.6) activities significantly increased as compared to the controls, whereas no significant change was observed in cv. Wuxi. Lipid peroxidation and cell membrane injury were enhanced in both cultivars. Net photosynthesis and stomatal conductance decreased in response to salt stress, but cv. Dafeng showed a smaller reduction in photosynthesis than cv. Wuxi. The results indicated that stomatal aperture limited leaf photosynthetic capacity in the NaCl-treated plants of both cultivars. However, significant reduction in the leaf chlorophyll content due to NaCl stress was observed only in cv. Wuxi. These results suggested that salt-tolerant Jerusalem artichoke varieties may have a better protection against reactive oxygen species, at least in part, by increasing the activity of antioxidant enzymes under salt stress.     

Differential Responses of <i>NHX1</i> and <i>SOS1</i> Gene Expressions to Salinity in two <i>Miscanthus sinensis</i> Anderss. Accessions with Different Salt Tolerance

The lignocellulosic crop Miscanthus spp. has been identified as a good candidate for biomass production. The responses of Miscanthus sinensis Anderss. to salinity were studied to satisfy the needs for high yields in marginal areas and to avoid competition with food production. The results indicated that the relative advantages of the tolerant accession over the sensitive one under saline conditions were associated with restricted Na⁺ accumulation in shoots. Seedlings of two accessions (salt-tolerant ‘JM0119’ and salt-sensitive ‘JM0099’) were subjected to 0 (control), 100, 200, and 300 mM NaCl stress to better understand the salt-induced biochemical responses of genes involved in Na⁺ accumulation in M. sinensis. The adaptation responses of genes encoding for Na⁺ /H⁺ antiporters, NHX1 and SOS1 to NaCl stress were examined in JM0119 and JM0099.The cDNA sequences of genes examined were highly conserved among the relatives of M. sinensis based on the sequencing on approximate 600 bp-long cDNA fragments obtained from degenerate PCR. These salt-induced variations of gene expression investigated by quantitative real-time PCR provided evidences for insights of the molecular mechanisms of salt tolerance in M. sinensis. The expression of NHX1 was up-regulated by salt stress in JM0119 shoot and root tissues. However, it was hardly affected in JM0099 shoot tissue except for a significant increase at the 100 mM salt treatment, and it was salt-suppressed in the JM0099 root tissue. In the root tissue, the expression of SOS1 was induced by the high salt treatment in JM0119 but repressed by all salt treatments in JM0099. Thus, the remarkably higher expression of NHX1 and SOS1 were associated with the resistance to Na⁺ toxicity by regulation of the Na⁺ influx, efflux, and sequestration under different salt conditions.     

Effects of long-term salt stress on antioxidant defence systems, leaf water relations and chloroplast ultrastructure of potato plants

The effect of long-term (30 days) NaCl treatments (100 mM and 200 mM) on the activity of some antioxidant enzymes, level of antioxidant metabolites, water relations and chloroplast ultrastructure, was studied in potato (Solanum tuberosum cv. Désirée) leaves. Salt stress negatively affected relative water content, leaf stomatal conductance and transpiration rate. In treated plants, proline was enhanced, but there was a significant decrease in ascorbate and proteins. Total superoxide dismutase activity was increased. The isozyme patterns detected in native gels from salt-irrigated plants were not changed although all the isoforms appeared more heavily stained due to higher activity. In contrast, at both levels of NaCl, catalase activity decreased and ascorbate peroxidase activity showed no significant change in comparison with an untreated control. At ultrastructural level, only thylakoid swelling and a decrease in the amount of grana stacking was observed in treated plants. The overall behaviour of the antioxidant enzymes suggests an increase of cellular H₂O₂ that would contribute to the oxidative stress of potato plants, but which may be alleviated somewhat by the enhanced levels of proline.     

Improvement of Selected Morphological,Physiological, and Biochemical Parameters of Banana (<i>Musa acuminata</i> L.) Using Potassium Silicate under Drought Stress Condition Grown <i>in vitro</i>

Drought stress has become more common in recent years as a result of climate change impacts on the production of banana crops and other fruit trees. The growth and productivity of Musa spp are severely impacted by the gradual degradation of water resources and the erratic distribution pattern of annual precipitation amount. The aim of the work includes increased drought tolerance in light of water scarcity in the world as a result of the bananas’ being gluttonous for water needs. This investigation was carried out from 2019 to 2020 to study the effect of potassium silicate on morphological growth and biochemical parameters of Musa acuminata L under drought stress by PEG. As a result, drought stress reduced the morphological characteristics such as shoots number, shoot length, roots number, and survival percentage and biochemical characteristics such as chlorophyll a, b, carotenoids, stomatal status, and RWC. While proline content increased in the leaf of M. acuminata L. Media complemented with K₂SiO₃ (2 to 6 mM) either individually or in combination with PEG led to an improvement in all morphological and biochemical characteristics. The activities of CAT, POD, and PPO enzymes increased signifi- cantly compared to control. Furthermore, the lowest PPO, CAT, and POD activity were achieved. Additionally, K₂SiO₃ treatments under drought stress successfully enhanced the leaf stomatal behavior. Our results suggest that K₂SiO₃ can help to maintain plant integrity in the tested cultivar under drought stress.     

Effects of Simulated Acid Precipitation on Photosynthesis,Chlorophyll Fluorescence,and Antioxidative Enzymes in Cucumis sativus L.

The effects of simulated acid rain on gas exchange, chlorophyll fluorescence, and anti-oxidative enzyme activity in cucumber seedlings (Cucumis sativus L. cv. Jingchun No. 4) were investigated. Acid rain significantly reduced net photosynthetic rate and mainly non-stomatal factors contributed to the decrease of photosynthesis during the experimental period. The reduced photosynthesis was associated with a decreased maximal photochemical efficiency (F_v/F_m) and the average quantum yield of the photosystem 2 (PS2) reaction centres (_PS2). Meanwhile, acid rain significantly increased the activities of guaiacol peroxidase (GPX) and superoxide dismutase (SOD), but decreased the activity of catalase (CAT) together with an increased content of malonyldialdehyde (MDA), Hence the changes in photosynthesis in acid rain treatment might be a secondary effect of acidity damage probably due to lipid peroxidation of lipids and proteins in thylakoid membrane rather than direct effect on PS2 reaction centre.     

Probucol treatment reverses antioxidant and functional deficit in diabetic cardiomyopathy

Earlier we reported that probucol treatment subsequent to the induction of diabetes can prevent diabetes-associated changes in myocardial antioxidants as well as function at 8 weeks. In this study, we examined the efficacy of probucol in the reversal of diabetes induced myocardial changes. Rats were made diabetic with a single injection of streptozotocin (65 mg/kg, i.v.). After 4 weeks of induction of diabetes, a group of animals was treated on alternate days with probucol (10 mg/kg i.p.), a known lipid lowering agent with antioxidant properties. At 8 weeks, there was a significant drop in the left ventricle (LVSP) and aortic systolic pressures (ASP) in the diabetic group. Hearts from these animals showed an increase in the thiobarbituric acid reacting substances (TBARS), indicating increased lipid peroxidation. This was accompanied by a decrease in the myocardial antioxidant enzymes activities, superoxide dismutase (SOD) and glutathione peroxidase (GSHPx). Myocardial catalase activity in the diabetic group was higher. In the diabetic + probucol group both LVSP and ASP showed significant recovery. This was also accompanied by an improvement in SOD and GSHPx activities and there was further increase in the catalase activity. Levels of the TBARS were decreased in this group. These data provide evidence that diabetic cardiomyopathy is associated with an antioxidant deficit which can be reversed with probucol treatment. Improved cardiac function with probucol may be due to the recovery of antioxidants in the heart.     

Induction of heat tolerance in wheat coleoptiles by calcium ions and its relation to oxidative stress

Effects of Ca²⁺ ions on the intensity of lipid peroxidation, activities of guaiacol peroxidase, superoxide dismutase (SOD), and catalase, as well as on heat resistance of winter wheat (Triticum aestivium L.) coleoptiles were examined. A preliminary incubation of coleoptile segments in a 5 mM CaCl₂ solution was shown to improve their survival rates after an injuring heat treatment (43.5°C). The effect of Ca²⁺ was suppressed by the inhibitor of Ca²⁺ channels (1 mM LaCl₃). An incubation of coleoptiles in the presence of 5 mM CaCl₂ prior to the stress treatment elevated the content of lipid peroxidation product, malondialdehyde (MDA) and stimulated the activities of guaiacol peroxidase, SOD, and catalase. After the heat exposure of untreated and Ca²⁺-treated seedlings, differential changes in MDA content and in activities of guaiacol peroxidase, SOD, and catalase were observed. It is concluded that a short-term oxidative stress arising in Ca²⁺-enriched plant tissues after the heat treatment is unrelated to their irreversible damage.Translated from Fiziologiya Rastenii, Vol. 52, No. 2, 2005, pp. 227–232.Original Russian Text Copyright © 2005 by Kolupaev, Akinina, Mokrousov.This revised version was published online in April 2005 with a corrected cover date.     

Effects of Barium Stress in <i>Brassica juncea</i> and <i>Cakile maritima</i>: The Indicator Role of Some Antioxidant Enzymes and Secondary Metabolites

Soil contamination by toxic trace metal elements, like barium (Ba), may stimulate various undesirable changes in the metabolic activity of plants. The plant responses are fast and with, direct or indirect, generation of reactive oxygen species (ROS). To cope with the stress imposed by the ROS production, plants developed a dual cellular system composed of enzymatic and non-enzymatic players that convert ROS, and their by-products, into stable nontoxic molecules. To assess the Ba stress response of two Brassicaceae species (Brassica juncea, a glycophyte, and Cakile maritime, a halophyte), plants were exposure to different Ba concentrations (0, 100, 200, 300 and 500 μM). The plants response was evaluated through their morphology and development, the determination of plant leaves antioxidant enzymatic activities and by the production of plants secondary metabolites. Results indicated that the two Brassicaceae species have the ability to survive in an environment containing Ba (even at 500 μM). The biomass production of C. maritima was slightly affected whereas an increase in biomass B. juncea was noticed. The stress imposed by Ba activated the antioxidant defense system in the two species, noticed by the changes in the leaves activity of catalase (CAT), ascorbate peroxidase (APX) and guaicol peroxidase (GPX), and of the secondary metabolites, through the production of total phenols and flavonoids. The enzymatic response was not similar within the two plant species: CAT and APX seem to have a more important role against the oxidative stress in C. maritima while in B. juncea is GPX. Overall, total phenols and flavonoids production was more significant in the plants aerial part than in the roots, of the both species. Although the two Brassicaceae species response was different, in both plants catalytic and non-catalytic transformation of ROS occurs, and both were able to overcome the Ba toxicity and prevent the cell damage.     

Heavy Metals Induce Lipid Peroxidation and Affect Antioxidants in Wheat Leaves

The possible role of Zn and Cr as catalytic inducers of free radicals in wheat leaves was investigated. Treatment of excess heavy metals decreased the chlorophyll and carotenoid content in wheat leaves with the increase in time of excision. A sharp increase in proline accumulation was marked with the increase in metal concentration. Total peroxide content and lipid peroxidation measured as malondialdehyde content showed uniform increase under metal treatment in excised leaves. At almost all concentrations, catalase, guaiacol peroxidase and superoxide dismutase activities decreased with a minor increase in the earlier days of excision. Though glutathione content decreased ascorbate content showed significant increase in wheat leaves under heavy metal treatment. This revised version was published online in July 2006 with corrections to the Cover Date.     

Lipid peroxidative damage on cadmium exposure and alterations in antioxidantsystem in rat erythrocytes: A study with relation to time

Cadmium induced lipid peroxidation (LPO) and the activity of antioxidantenzymes after the administration of a single dose of CdCl 2 (0.4 mg kg body wt, ip) was studied in rat erythrocytes.Cd intoxication increased erythrocyte LPO along with a decrease insuperoxide dismutase (SOD) up to three days of Cd treatment. Thedecrease in erythrocyte catalase (CAT) activity was marked within9 h of Cd intoxication. After three days of Cd treatment, LPOdecreased towards normal, along with an increase in erythrocyteSOC and CAT activity. Blood glutathione (GSH) decreased significantlywithin 24 h of Cd treatment, followed by an increase towards normal.Erythrocyte glutathione S-transferase (GST) activity increased up to10 days of Cd intoxication, probably in an attempt to reduce Cd toxicity.Serum glutamate pyruvate transaminase (SGPT), serum alkaline phosphatase(SALP) and serum bilirubin increased up to 10 days of Cd intoxication.Blood urea increased significantly up to three days, followed by a decreasetowards normal. The results show that Cd induced LPO was associated with adecrease in antioxidant enzymes and GSH in erythrocytes; as these antioxidantsincrease in erythrocytes with recovery from Cd intoxication, the Cd inducedLPO reversed towards normal. The increase in the SGPT, SALP and serum bilirubincorrelated with LPO. The results suggest that Cd intoxication induces oxidativestress and alters the antioxidant system, resulting in oxidative damage torat erythrocytes. © Rapid Science 1998     

Water stress-induced oxidative damage and antioxidant responses in micropropagated banana plantlets

Oxidative injury and antioxidant responses were investigated in two banana genotypes (Musa AAA Berangan and Musa AA Mas) subjected to 40 % PEG-induced water stress. PEG treatment resulted in oxidative injury, as expressed in increased lipid peroxidation and reduced membrane stability index, in both cultivars; however, greater oxidative injury was detected in Mas. Under PEG treatment, catalase activity and glutathione reductase activity were enhanced in both cultivars, but were higher in Mas. Ascorbate peroxidase activity was enhanced in Berangan under water stress, but was unaffected in Mas. Meanwhile, superoxide dismutase activity was inhibited in both cultivars under water stress, but higher activity was detected in Berangan. Higher ascorbate peroxidase and superoxide dismutase activities were associated with greater protection against water stress-induced oxidative injury.