Effect of 24-Epibrassinolide on Antioxidative Defence System Against Lead-Induced Oxidative Stress in The Roots of <Emphasis Type="Italic">Brassica juncea</Emphasis> L. Seedlings

Lead (Pb) toxicity causes oxidative stress by increasing the production of reactive oxygen species. The aim of the present study was to investigate the role of 24-epibrassinolide (24-EBL) on the antioxidant defence system as a response to Pb stress in Brassica juncea L. Surface-sterilized seeds were exposed to Pb ion (0 and 2 mM) toxicity in Petri dishes and subsequently, the seeds were sprayed with either (i) deionized water or (ii) different concentrations (10^–12, 10^–10, and 10^–8 M) of 24-EBL on alternate days. After nine days, the roots of the B. juncea seedlings were harvested to analyze the heavy metal content, root length, hydrogen peroxide level, lipid peroxidation, total protein content and activities of the antioxidant enzymes (superoxide dismutase, catalase, ascorbate peroxidase, peroxidase, glutathione reductase and glutathione-S-transferase). According to our results, the Pb ions accumulated by the B. juncea roots led to oxidative stress by increasing the level of H₂O₂ and malondialdehyde, and thus, increased the activity of the antioxidative enzymes (except for catalase) and the growth and total protein content decreased. Whereas, the 24-EBL treatment to the roots of Pb stressed seedlings was able to alleviate the Pb-induced oxidative stress. Upon the application of 24-EBL, a reduction in Pb accumulation, H₂O₂ and malondialdehyde levels as well as an increased total protein content and activity of antioxidative enzymes detoxifying hydrogen peroxide (catalase, ascorbate peroxidase and peroxidase) were observed. As a result, the stress protective properties of 24-EBL depending on concentration in B. juncea roots were revealed in this study.     

Ameliorative Role of Pre-Sowing Proline Treatment in <i>Coriandrum sativum</i> L. Seedlings under Mercury Toxicity

Heavy metal toxicity is one of the major ecosystem concerns globally in present time and is also responsible for significant threat to agronomic crops. The current work was conducted to investigate the possible ameliorative role of proline in Coriandrum sativum L. seedlings treated with mercury (Hg). The seedlings were exposed to different concentrations of Hg (0, 0.1, 0.3 and 0.5 mM) for 20 days. The effects of pre-sowing treatment with proline were studied on C. sativum seedlings in terms of pigment (chlorophylls, carotenoids and anthocyanins), malondialdehyde (MDA), antioxidant compound (glutathione, total phenolic compounds, ascorbic acid) and osmolytes (proline, glycine betaine). Additionally, activities of antioxidant enzymes, namely catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX) and dehydroascorbate reductase (DHAR) were also studied. A strong decline of photosynthetic pigment concentrations was observed in leaves of C. sativum under Hg toxicity. Treatment of seeds with proline reduced the loss of photosynthetic pigments, counteract Hg-triggered oxidative stress, likely preserving the functionality of antioxidant apparatus under Hg stress. The increment of total polyphenols and glycine betaine also contributed in ameliorating Hg toxicity, suggesting the use of exogenous proline as a potential method to enhance the plant tolerance against heavy metal stress.     

Effect of exogenous H2O2 on antioxidant enzymes of Brassica juncea L. seedlings in relation to 24-epibrassinolide under chilling stress

Hydrogen peroxide is most stable molecule among reactive oxygen species, which play a vital role in growth and development of plant as signaling molecule at low concentration in response to various abiotic and biotic stresses. Exogenous application of H2O2 is known to induce chilling tolerance in plants. Brassinosteroids are plant steroid hormones known for their anti-stress properties. In this study, effect of exogenous H2O2 on antioxidant defense system of Brassica juncea L. seedlings was investigated in 24-epibrassinolide (24-EBL) treated and untreated seedlings under chilling stress. The surface sterilized seeds of B. juncea L. were germinated in petriplates containing different concentrations of H2O2 alone and in combination with 10(-8) M 24-EBL. Chilling treatment (4 degrees C) was given to 10-days old seedlings grown in different treatments for 6 h daily up to 3 days. 24 h recovery period was given to chilling treated seedlings by placing at 25 degrees C + 2 degrees C and harvested for antioxidant enzymes on 14th day after sowing (DAS). Treatment of 24-EBL in combination with H2O2 (15 and 20 mM) helped in reducing the toxicity of seed and seedlings due to H2O2 exposure on their germination rate, shoot and root length respectively. 24-EBL treatment at seed and seedling stage helped in alleviating the toxic effect of H2O2 through antioxidant defense system by increasing the activities of various enzymes involved in antioxidant defense system such as catalase (CAT, E.C. 1.11.1.6), ascorbate peroxidase (APOX, E.C. 1.11.1.11), and superoxide dismutase (SOD, E.C. 1.15.1.1). In conclusion, exogenous pretreatment of H2O2 to seeds of B. juncea L. adapted the seedlings to tolerate chilling stress, which was further ameliorated in combination of H2O2 with 24-EBL.     

Effects of 28-homobrassinolide on nickel uptake,protein content and antioxidative defence system in <Emphasis Type="Italic">Brassica juncea</Emphasis>

The effects of 28-homobrassinolide (HBL) on nickel uptake, protein content and activities of antioxidative enzymes were determined in the seedlings of Brassica juncea L. The seeds were treated with different concentrations (0, 0.01, 1 and 100 nM) of HBL for 8 h and then sown in the Petri plates containing various concentrations (0, 25, 50 and 100 mg dm⁻³) of nickel. After 7 d, observations were made on shoot and root length, Ni uptake, protein content and activities of antioxidative enzymes (guaiacol peroxidase, catalase, glutathione reductase, ascorbate peroxidase and superoxide dismutase). The growth of seedlings was inhibited by Ni, however, less after HBL pre-treatment. The protein content and antioxidative enzyme activities were also increased by HBL treatment.     

Effect of salicylic acid on salinity-induced changes in Brassica juncea

Seeds of Indian mustard (Brassica juncea (L.) Czern.et Coss.) were exposed to 0,50,100 and 150 mmol/L NaCl for 8h and seeds were sown in an earthen pot.These stressed seedlings were subsequently sprayed with 10 μrnol/L salicylic acid (SA) at 30 d and were sampled at 60 d to assess the changes in growth,photosynthesis and antioxidant enzymes.The seedlings raised from the seeds treated with NaCl had significantly reduced growth and the activities of carbonic anhydrase,nitrate reductase and photosynthesis,and the decrease was proportional to the increase in NaCl concentration.However,the antioxidant enzymes (catalase,peroxidase and superoxide dismutase) and proline content was enhanced in response to NaCl and/or SA treatment,where their interaction had an additive effect.Moreover,the toxic effects generated by the lower concentration of NaCl (50 mmol/L) were completely overcome by the application of SA.It was,therefore,concluded that SA ameliorated the stress generated by NaCl through the alleviated antioxidant system.     

Comparative Effects of Benzoic Acid and Water Stress on Wheat Seedlings

In the present study, we compared the effects of allelochemical, water stress (WS) and their combinations on seedling growth, biochemical parameters and responses of antioxidative enzymes in Triticum aestivum L. The wheat seedlings were treated with 0.5, 1.0 and 1.5 mM concentrations of benzoic acid (BA), with and without water stress. Leaf water status, photosynthetic pigments, protein content, amount of proline and activities of nitrate reductase and antioxidant enzymes were examined. Allelopathic stress resulted in reduction of seedling height. Height of water stressed seedlings greatly decreased. The combined treatments, BA + WS further decreased the seedling height. BA treatment with and without water stress caused significant reduction in dry weight of the seedlings. BA and water stress decreased relative water content, pigments and protein content. Total soluble sugar content and nitrate reductase activity were variedly affected under all treatments. Proline content and lipid peroxidation increased in treatments with BA and water stress. Activity of superoxide dismutase increased significantly (P < 0.05) while catalase activity decreased in all treatments. Ascorbate peroxidase and guaiacol peroxidase activities were higher as compared with catalase which seems to protect wheat seedlings from oxidative stress. Water stress elevated the toxic effect of allelochemical.     

Effect of 24-epibrassinolide on growth, protein content and antioxidative defense system of Brassica juncea L. subjected to cobalt ion toxicity

Brassica juncea L. plants were subjected to cobalt (Co) ion (0, 5?×?10^?4, 10^?3, 1.5?×?10^?3 and 2?×?10^?3?M) toxicity and were sprayed with different concentrations of 24-epibrassinolide (24-EBL) (0, 10^?10, 10^?8 and 10^?6?M) at 15-day stage after sowing. They were sampled at 30 and 60?days after sowing and analyzed for growth parameters in terms of shoot length and number of leaves. Thereafter, leaves were excised and content of proteins and the activities of antioxidative enzymes (superoxide dismutase (SOD) (EC 1.15.1.1) catalase (CAT) (EC 1.11.1.6), ascorbate peroxidase (APOX) (EC 1.11.1.11), guaiacol peroxidase (POD) (EC 1.11.1.7) glutathione reductase (GR) (EC 1.6.4.2), monodehydroascorbate reductase (MDHAR) (EC 1.1.5.4) and dehydroascorbate reductase (DHAR) (EC 1.8.5.1)) were analyzed. The plants exposed to cobalt ion exhibited a significant decline in growth in terms of shoot length and number of leaves. However, foliar spray treatment with 24-EBL was able to alleviate the stress generated by cobalt ion and significantly improved the above parameters. The activities of antioxidative enzymes (SOD, CAT, POD, GR, APOX, MDHAR and DHAR) and protein content were also regulated considerably in leaves of plants treated with 24-EBL alone, 10^?8?M concentration being the most effective. The activities of antioxidative enzymes also increased in leaves of B. juncea plants by the application of cobalt ion to soil and consequently sprayed with 24-EBL. Similarly, the protein content was also regulated in leaves of B. juncea plants treated with 24-EBL as compared to untreated control plants, thereby revealing stress-protective properties of 24-EBL.     

28-homobrassinolide improves growth and photosynthesis in <Emphasis Type="Italic">Cucumis sativus</Emphasis> L. through an enhanced antioxidant system in the presence of chilling stress

The ameliorative role of 28-homobrassinolide under chilling stress in various growth, photosynthesis, enzymes and biochemical parameters of cucumber (Cucumis sativus L.) were investigated. Cucumber seedlings were sprayed with 0 (control), 10⁻⁸, or 10⁻⁶ M of 28-homobrassinolide at the 30-day stage. 48 h after treatment plants were exposed for 18 h to chilling temperature (10/8°C, 5/3°C). The most evident effect of chilling stress was the marked reduction in plant growth, chlorophyll (Chl) content, and net photosynthetic rate, efficiency of photosystem II and activities of nitrate reductase and carbonic anhydrase. Moreover, the activities of antioxidant enzymes; catalase (E.C. 1.11.1.6), peroxidase (E.C.1.11.1.7), superoxide dismutase (E.C. 1.15.1.1) along with the proline content in leaves of the cucumber seedlings increased in proportion to chilling temperature. The stressed seedlings of cucumber pretreated with 28-homobrassinolide maintained a higher value of antioxidant enzymes and proline content over the control suggesting the protective mechanism against the ill-effect caused by chilling stress might be operative through an improved antioxidant system. Furthermore, the protective role of 28-homobrassinolide was reflected in improved growth, water relations, photosynthesis and maximum quantum yield of photosystem II both in the presence and absence of chilling stress.     

Exogenous salicylic acid improves salinity tolerance of <Emphasis Type="Italic">Nitraria tangutorum</Emphasis>

In the present study, the physiological responses of Nitraria tangutorum Bobr. seedlings to NaCl stress and the regulatory function of exogenous application of salicylic acid (SA) were investigated. NaCl in low concentration (100 mM) increased while in higher concentrations (200–400 mM) decreased the individual plant dry weights (wt) of seedlings. Decreased relative water content (RWC) and chlorophyll content were observed in the leaves of seedlings subjected to salinity stress (100–400 mM NaCl). Furthermore, NaCl stress significantly increased electrolyte leakage and malondialdehyde (MDA) content. The levels of osmotic adjustment solutes including proline, soluble sugars, and soluble protein were enhanced under NaCl treatments as compared to the control. In contrast, exogenous application of SA (0.5–1.5 mM) to the roots of seedlings showed notable amelioration effects on the inhibition of individual plant dry wt, RWC, and chlorophyll content. The increases in electrolyte leakage and MDA content in the leaves of NaCl-treated seedlings were markedly inhibited by SA application. The SA application further increased the contents of proline, soluble sugars, and soluble protein. The activities of antioxidant enzymes including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) were up-regulated by NaCl stress and the activities of SOD, POD, and CAT were further enhanced by SA treatments. Application of SA in low concentration (0.5 mM) enhanced while in higher concentrations (1.0 and 1.5 mM) inhibited APX activities in leaves of NaCl-treated seedlings. These results indicate that SA effectively alleviated the adverse effects of NaCl stress on N. tangutorum.     

Alleviation of Cadmium Toxicity in Brassica juncea L. (Czern. & Coss.) by Calcium Application Involves Various Physiological and Biochemical Strategies

Calcium (Ca) plays important role in plant development and response to various environmental stresses. However, its involvement in mitigation of heavy metal stress in plants remains elusive. In this study, we examined the effect of Ca (50 mM) in controlling cadmium (Cd) uptake in mustard (Brassica juncea L.) plants exposed to toxic levels of Cd (200 mg L⁻¹ and 300 mg L⁻¹). The Cd treatment showed substantial decrease in plant height, root length, dry weight, pigments and protein content. Application of Ca improved the growth and biomass yield of the Cd-stressed mustard seedlings. More importantly, the oil content of mustard seeds of Cd-stressed plants was also enhanced with Ca treatment. Proline was significantly increased in mustard plants under Cd stress, and exogenously sprayed Ca was found to have a positive impact on proline content in Cd-stressed plants. Different concentrations of Cd increased lipid peroxidation but the application of Ca minimized it to appreciable level in Cd-treated plants. Excessive Cd treatment enhanced the activities of antioxidant enzymes superoxide dismutase, ascorbate peroxidase and glutathione reductase, which were further enhanced by the addition of Ca. Additionally, Cd stress caused reduced uptake of essential elements and increased Cd accumulation in roots and shoots. However, application of Ca enhanced the concentration of essential elements and decreased Cd accumulation in Cd-stressed plants. Our results indicated that application of Ca enables mustard plant to withstand the deleterious effect of Cd, resulting in improved growth and seed quality of mustard plants.     

24-Epibrassinolide alleviated zinc-induced oxidative stress in radish (Raphanus sativus L.) seedlings by enhancing antioxidative system

This article encompasses the results on the effects of 24-epibrassinolide (EBR) on the changes in reactive oxygen species (ROS) and activities of antioxidative enzymes in radish (Raphanus sativus L.) seedlings subjected to zinc (Zn) stress. Zn toxicity resulted in significant enhancement in the level of membrane lipid peroxidation, protein oxidation, contents of hydrogen peroxide (H₂O₂) and hydroxyl radical (^·OH), the production rate of superoxide radicals (O ₂ ^·? ) and the activities of lipoxygenase and NADPH oxidase in radish seedlings indicating the induction of oxidative stress. However, Zn-mediated enhancement in indices of oxidative stress was considerably decreased by EBR treatment. EBR application enhanced the activities of catalase, superoxide dismutase, guaiacol peroxidase, glutathione peroxidase, and peroxidase in radish seedlings under Zn stress. EBR treatment reduced the activity of ascorbic acid oxidase in Zn stressed seedlings. Further, EBR application also enhanced the free proline and phenol levels under Zn stress. From the results obtained in this study, it can be inferred that EBR application alleviated oxidative damage caused by over production of ROS through the up regulation of antioxidative capacity in Zn stressed radish seedlings.     

Chromium stress mitigation by polyamine-brassinosteroid application involves phytohormonal and physiological strategies in Raphanus sativus L

Brassinosteroids (BRs) and polyamines (PAs) are well-established growth regulators playing key roles in stress management among plants. In the present study, we evaluated the effects of epibrassinolide (EBL, an active BR) and spermidine (Spd, an active PA) on the tolerance of radish to oxidative stress induced by Cr (VI) metal. Our investigation aimed to study the impacts of EBL (10(-9) M) and/or Spd (1 mM) on the biochemical and physiological responses of radish (Raphanus sativus L.) under Cr-stress. Applications of EBL and/or Spd were found to improve growth of Cr-stressed seedlings in terms of root length, shoot length and fresh weight. Our data also indicated that applications of EBL and Spd have significant impacts, particularly when applied together, on the endogenous titers of PAs, free and bound forms of IAA and ABA in seedlings treated with Cr-stress. Additionally, co-applications of EBL and Spd modulated more remarkably the titers of antioxidants (glutathione, ascorbic acid, proline, glycine betaine and total phenol) and activities of antioxidant enzymes (guaicol peroxidase, catalase, superoxide dismutase and glutathione reductase) in Cr-stressed plants than their individual applications. Attenuation of Cr-stress by EBL and/or Spd (more efficient with EBL and Spd combination) was also supported by enhanced values of stress indices, such as phytochelatins, photosynthetic pigments and total soluble sugars, and reduction in malondialdehyde and H(2)O(2) levels in Cr-treated seedlings. Diminution of ROS production and enhanced ROS scavenging capacities were also noted for EBL and/or Spd under Cr-stress. However, no significant reduction in Cr uptake was observed for co-application of EBL and Spd when compared to their individual treatments in Cr-stressed seedlings. Taken together, our results demonstrate that co-applications of EBL and Spd are more effective than their independent treatments in lowering the Cr-induced oxidative stress in radish, leading to improved growth of radish seedlings under Cr-stress.     

Differential biochemical responses of wheat shoots and roots to nickel stress: antioxidative reactions and proline accumulation

Wheat (Triticum aestivum L. cv. ‘Zyta’) seedlings were treated with 10, 100 and 200 μM Ni. Tissue Ni accumulation, length, relative water content (RWC), proline and H₂O₂ concentrations as well as the activities of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (POD) and glutathione S-transferase (GST) were studied in the shoots and roots after 6 days of Ni exposure. Treatment with Ni, except for its lowest concentration, resulted in a significant reduction in wheat growth. In comparison to the shoots, the roots showed greater inhibition of elongation, which corresponded with higher accumulation of Ni in these organs. Both shoots and roots responded to Ni application with a decrease in RWC and enhancement in proline concentration. Greater dehydration of the shoot tissue was accompanied by more intense accumulation of proline. Treatment of the wheat seedlings with the highest concentration of Ni led to about 60% increase in H₂O₂ concentration in both studied organs. Apart from CAT, constitutive activities of antioxidative enzymes were much higher in the roots than in the shoots. Exposure of the seedlings to Ni resulted in SOD activity decline, which was more marked in the roots. While the shoots showed a substantial decrease (up to 30%) in CAT activity, in the roots the activity of this enzyme remained unchanged. After Ni application APX, POD and GST activities increased several-fold in the shoots, whereas in the roots they were not significantly altered. The results suggest that differential antioxidative responses of the shoots and roots of wheat seedlings to Ni stress might be related to diverse constitutive levels of antioxidant enzyme activities in both organs.     

外源一氧化氮对盐胁迫下黑麦草幼苗生长及生理特性的影响

研究了外源一氧化氮（nitric oxide,NO）对盐胁迫下多年生黑麦草幼苗生长及相关生理指标变化的影响。结果表明,与对照相比,50～200μmol&#183;L-1NO供体硝普钠（sodium nitroprusside,SNP）可缓解盐胁迫对黑麦草幼苗生长的抑制作用,其中100μmo&#183;lL-1SNP缓解作用最强。外施SNP显著缓解了盐胁迫导致的叶片相对电导率、K＋与Na＋比率、丙二醛含量和活性氧水平的增加,提高了盐胁迫下幼苗叶子中脯氨酸含量和超氧化物歧化酶、过氧化氢酶、抗坏血酸过氧化物酶和过氧化物酶等抗氧化酶的活性。这些结果说明,NO可能通过降低细胞吸收Na＋的量、增加细胞吸收K＋的量和脯氨酸含量以及激活抗氧化保护酶等减轻了盐对黑麦草的伤害,提高了黑麦草的抗盐性。     

Enhancing effects of 24-epibrassinolide and Putrescine on the antioxidant capacity and free radical scavenging activity of <Emphasis Type="Italic">Raphanus sativus</Emphasis> seedlings under Cu ion stress

The present investigation recorded significant restoration of seedling growth (root length, shoot length and fresh weight) upon application of 24-epibrassinolide (EBL) and putrescine (Put) to 7-day-old seedlings of Raphanus sativus L. cv. Pusa chetki grown under copper (Cu) ion stress. EBL and Put with/or without Cu ion treated seedlings showed increased titers of ascorbic acid, total phenols and proline when compared with Cu-stressed seedlings. Differential responses in the activities of guaiacol peroxidase (GPOX) and catalase (CAT) were noted for EBL and Put alone or with/or without Cu ion treatment. Decreased activities of glutathione reductase (GR) and superoxide dismutase (SOD) noted for EBL and Put alone were observed to enhance significantly when applied in combination with Cu ion solution. A remarkable decrease in malondialdehyde contents was observed in seedlings treated with EBL and Put alone and with/or without Cu ion stress. Enhanced free radical scavenging activities were also recorded for seedlings given EBL and Put alone or in combination over Cu ion stressed seedlings. Maximum DPPH activity was observed in seedlings treated with Put and EBL 10⁻⁹ M + Put. Significant enhancements in deoxyribose and reducing power activities were too recorded for Put, EBL and Put + 10⁻⁹ M EBL treatments. Improved seedling growth, antioxidant levels (ascorbic acid, total phenols and proline) and enzymic (GPOX, CAT, SOD and GR) activities and free radical scavenging capacities along with reduced membrane damage in seedlings given EBL and Put with/or without Cu stress suggests significant and positive interactions of EBL and Put in alleviating the Cu ion induced oxidative damage in radish seedlings.     

Ethephon mitigates nickel stress by modulating antioxidant system,glyoxalase system and proline metabolism in Indian mustard

The role of ethylene (through application of ethephon) in the regulation of nickel (Ni) stress tolerance was investigated in this study. Ethephon at concentration of 200 µl l^?1 was applied to mustard (Brassica juncea) plants grown without and with 200 mg kg^?1 soil Ni to study the increased growth traits, biochemical attributes, photosynthetic efficiency, nutrients content, activities of antioxidants such as superoxide dismutase, ascorbate peroxidase, glutathione reductase, and glutathione peroxidase, glyoxalase systems and enhanced the proline metabolism. In the absence of ethephon, Ni increased oxidative stress with a concomitant decrease in photosynthesis, growth and nutrients content. However, application of ethephon positively increased growth traits, photosynthetic parameters, nutrients content and also elevated the generation of antioxidants enzymes and glyoxalase systems, proline production to combat oxidative stress. Plants water relations and cellular homeostasis were maintained through increased photosynthetic efficiency and proline production. This signifies the role of ethylene in mediating Ni tolerance via regulating proline production and photosynthetic capacity. Ethephon can be used as an exogenous supplement on plants to confer Ni tolerance. The results can be exploited to develop tolerance in plants via gene editing technology encoding enzymes responsible for proline synthesis, antioxidant defence, glyoxalase systems and photosynthetic effectiveness.

     

Antioxidant defense system,lipid peroxidation,proline-metabolizing enzymes,and biochemical activities in two <Emphasis Type="Italic">Morus alba</Emphasis> genotypes subjected to NaCl stress

Salt stress-induced changes in antioxidant enzymes, lipid peroxidation, proline and glycine betaine contents, and proline-metabolizing enzymes were examined in the leaves of two mulberry cultivars (Local and Sujanpuri). With increasing salinity up to 150 mM NaCl, superoxide dismutase, catalase, ascor-bate peroxidase, guaiacol peroxidase, glutathione reductase, and monodehydroascorbate reductase activities were increased in both cultivars as compared to control, but more pronounced increase was observed in cv. Local. Salt stress enhanced the rate of lipid peroxidation (as indicated by increasing MDA content) in both cultivars. Under NaCl stress, cv. Local showed less change in the MDA content than cv. Sujanpuri. Salt stress resulted in a significant accumulation of free proline in mulberry leaves, and more accumulation was detected in cv. Local than cv. Sujanpuri. The leaves of cv. Local showed 9-fold accumulation of glycine betaine in comparision with cv. Sujanpuri after 20 days at 150 mM NaCl. A decrease in proline oxidase activity and an increase in γ-glutamyl kinase activity were observed with increasing NaClconcentration. The relative water content and electrolyte leakage also decreased after increasing the NaCl concentration, but a decrease was more pronounced in cv. Sujanpuri than in cv. Local. The results indicate that oxidative stress may play an important role in salt-stressed mulberry plants and cv. Local have more efficient antioxidant characteristics, which could provide for a better protection against oxidative stress.     

Coal fly ash and nitrogen application as eco-friendly approaches for modulating the growth,yield, and biochemical constituents of radish plants

Plants are confronting a variety of environmental hazards as a result of fast climate change, which has a detrimental influence on soil, plant growth, and nutrient status. As a result, the present study aims to evaluate the influence of various fly ash concentrations (5, 10, 15, 20, 25, 30, and 35% FA) mixed with the optimum concentrations of nitrogen in the form of urea (0.5 g pot^?1) on the growth, productivity and biochemical constituents of radish plants. Energy-dispersive X-ray spectroscopy (EDX) and scanning electron microscopy (SEM) were used to assess soil physical–chemical properties and FA nutrient status. Results suggested that FA added many essential plant nutrients to the growth substrate and improved some important soil characteristics such as pH, electric conductivity, porosity, and water holding capacity. Also, the results revealed that the low concentrations of FA up to 20% were found to boost radish growth, yield, chlorophyll, carotenoids, and mineral content. While the highest concentrations of FA (25–35%) decreased radish growth and yield, increased oxidative stress through increased lipid peroxidation (MDA) and caused a significant boost in ascorbic acid, proline, protein, and antioxidant enzyme activities. Furthermore, SEM of radish leaf revealed an enhancement in the stomatal pore of radish leaf under different levels of FA. In conclusion, combining 15% fly ash with 0.5 g nitrogen in the form of urea significantly enhanced radish yield by enhancing antioxidant activity such as catalase, peroxidase, ascorbate peroxidase, Guaiacol peroxidase, superoxide dismutase, nitrate reductase and reducing oxidative stress, potentially reducing fly ash accumulation and environmental pollution.     

The effects of Se phytotoxicity on the antioxidant systems of leaf tissues in barley (Hordeum vulgare L.) seedlings

A hydroponic experiment was carried out in a growth chamber to investigate the impact of Selenium (Se) levels on physiological and biochemical characteristics of a barley cultivar. Membrane lipid peroxidation (LPO), proline accumulation and antioxidant activities of some enzymes of barley seedlings under Se toxicity were investigated. Significant increase in thiobarbituric acid reactive substance (TBARS) content, and a stimulation of catalase (CAT, 1.11.1.6), ascorbate peroxidase (APX, 1.11.1.11), glutathione reductase (GR, 1.6.4.2), and glutathione S-transferase (GST, 2.5.1.18) activities were recorded in barley seedlings subjected to 2, 4, 8, 16 ppm Se. Superoxide dismutase (SOD, EC 1.15.1.1) activity was not altered significantly. Plant height and chlorophyll content of the seedlings were also affected significantly in a dose dependent manner by Se treatment. Considerable amount of proline accumulation was also observed in response to Se treatment. The results indicated that increases in the activities of the antioxidant enzymes were not sufficient to protect cell membrane against Se toxicity.     

Metal accumulation and response of antioxidant enzymes in seedlings and adult sunflower mutants with improved metal removal traits on a metal-contaminated soil

Sunflower mutant lines with an enhanced tolerance and metal accumulation capacity obtained by mutation breeding have been proposed for Zn, Cd and Cu removal from metal-contaminated soils in previous studies. However, soils contaminated with trace elements induce various biochemical alterations in plants leading to oxidative stress. There is a lack of knowledge concerning the metal accumulation and antioxidant responses during the growth and development of sunflowers. This study, therefore, aimed to characterise metal accumulation and possible metal detoxification mechanisms in young seedlings and adult sunflowers. Beside the inbred line, two mutant lines with an improved growth and enhanced metal uptake capacity on a metal contaminated soil were investigated in more detail.Sunflowers cultivated on a metal-contaminated soil in the greenhouse showed a decrease in shoot biomass and chlorophyll concentration in two different developmental stages. Adult sunflowers showed a lower sensitivity to metal toxicity than young seedlings, whereas mutant lines were more tolerant to metal stress than the control. Mutant lines also produced a higher amount of carotenoids on a metal-contaminated soil than on the control soil, indicating a possible protective mechanism of sunflower mutants against oxidative stress caused by Cd and excess Zn.Heavy metals primarily increased the activity of antioxidant enzymes involved in the ascorbate–glutathione cycle in sunflower leaves. Activity of dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDHAR) and glutathione reductase (GR) was strongly increased in young seedlings exposed to heavy metals. The enzyme activities were even more pronounced in mutant lines. A significantly increased ascorbate peroxidase (APOX) activity in adult sunflowers exposed to heavy metals indicated an elevated use of ascorbate after a longer exposure to metal stress.An increased antioxidant level corresponded to a high Cd and Zn accumulation in young and adult sunflowers. Metal distribution, zinc translocation in particular, from the root into the shoot tissue obviously increased during sunflower growth and ripening. Altogether, these results suggest that sunflower plants, primarily the mutant lines, possess an efficient defence mechanism against oxidative stress caused by metal toxicity. A good tolerance of sunflowers toward heavy metals coupled with an increased metal accumulation capacity might contribute to an efficient removal of heavy metals from a polluted area.