Journal of Plant Process and Function

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1 Department of agronomy and plant breeding, College of Agricultural, Isfahan University of Techchnology, Iran *Corresponding Author: Abstract: The effects of salt stress on the activity of ascorbate peroxidase (APX), glutathione reductase (GR), superoxide dismutase (SOD) enzymes, carotenoid content, the rate of lipid peroxidation (LP) in term of thiobarbituric acid-reactive substances (TBARS) content and grain yield were investigated. Eighteen triticale lines comprising 9 doubled haploid (DH) lines and 9 their corresponding F8 lines as well as two bread wheat cultivars ('Roshan' as a drought tolerant and 'Kavir' as a salt tolerant cultivar), were used. A randomized complete block design with three replications was used for each environmental condition (non-stressed and salt-stressed conditions) at the Research Farm of College of Agriculture, Isfahan University of Technology in a silty clay loam soil in 2008-2009. Both salt stressed and non-stressed experiments were irrigated with water having EC of 1 dS m-1 until mid-jointing stage (43 growth stage of Zadoks scale), and afterward salt-stressed experiment was irrigated with saline water containing 175 mM NaCl and EC= 16 dS m-1. Salinity led to an increase in the enzymes activities and LP and decrease in carotenoid content in the leaves of both triticale and wheat genotypes. An inverse and significant relationship between grain yield loss due to salinity stress with carotenoid content was observed under salinity stress (r = -0.54*). Under both conditions, negative and significant correlations (r = -0.61**) were observed between grain yield and LP. The orthogonal comparison between triticale line and wheat cultivars revealed the superiority of triticale lines for the production of antioxidants and less LP in triticale than wheat under both environmental conditions, which may be related to the development of relatively higher salt tolerant in triticale.

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Rozita Kabiri, Fatemeh Nasibi*, Hassan Farahbakhsh 1Department of Agronomy, Faculty of Agriculture, 2Department of Biology, Faculty of Sciences and 3Horticultural Research Institute, Shahid Bahonar University of Kerman (Received: 01 October 2012 Accepted: 17 March 2013) Abstract: Drought stress is one of the main stresses that inhibits the growth of plants due to mainly disturbance of the balance between production of reactive oxygen species and antioxidant defense and thereby causing oxidative stress. Evaluation of medicinal plants tolerance to drought stress in order to plant them in dry region is very important. In this research, oxidative parameters of drought stress induced by different concentration of polyethylene glycol solutions in Nigella plant were investigated. To control experimental conditions including the inhibitory effects of the other factors such as soil nutrition the hydroponic medium was used. In this study, drought stress significantly increased the H2O2 content, lipid peroxidation and lipoxygenase activity which were showed the oxidative stress induced by drought in Nigella plants. Study of the defense mechanisms, through the measurement of the antioxidant enzymes activities indicated that drought stress increased the activity of ascorbate peroxidase, catalase and guaiacol peroxidase. However in this research, we observed that the increment in drought level had no significant effects on catalase and guaiacol peroxidase activity. It seemed that in this investigation the increment of proline might be related to both osmotic and antioxidant characteristic of this compound. Increase of lipid peroxidation and H2O2 content in drought stress showed that the scavenging and quenching of ROS were out of the plant ability and the induction of plant defense mechanism against oxidative damages was not effective. Therefore, the application of exogenous protect compound could increase the antioxidant capacity of plant against stress condition. *Corresponding author:

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The effects of different concentrations of walnut leaf extract on physiological and biochemical characteristics of parsley plants inoculated with mycorrhizal fungus Glomus versiforme and non-mycorrhizal plants were studied under greenhouse conditions. In the present study, three different concentrations of walnut extract (full extract, half and quarter concentration levels) were used. The results of the 45 day-old plants showed that the increasing of the concentration of walnut extract decreased amounts of chlorophyll a and b but increased the carotenoids content. This increase was more pronounced in mycorrhizal plants than non-mycorrhizal ones. When ¼ concentration of extract was applied the total protein content in mycorrhizal and non-mycorrhizal plant shoots was increased and then decreased at higher concentrations with increasing in concentrations of aqueous extract of walnut leaves. The free amino acids and proline content in plants were increased but such effects in non-mycorrhizal plants were greater than in mycorrhizal ones. Ascorbate peroxidase (APX) and Guaiacol peroxidase (GPX) activities in mycorrhizal and non-mycorrhizal plants also increased due to walnut extract, but the increased activity of these enzymes was higher in the inoculated plants. Results of this study indicated that by inoculating mycorrhizal fungi with root of parsley adverse potential effects of allelopathic extract on the physiological and biochemical characteristics of these plants.

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In order to evaluate the allelopatic potential of sunflower alcoholic extract against winter wild oat (Avena ludoviciana) at germiantion and vegetative growth stage two expriments were coducted in Islamic Azad University, Shoushtar branch at 2012. Both expriments were laid out according to Completely Randomized Design with five replications and treatments were various concentration of sunflower extract (0, 5,10,15 and20 gr L-1). Results indicated sunflower alcoholic extract application exhibited gradual rise inhibitory effect on seed germination, seedling weight, antioxidant enzymes activity and -amylase enzyme activity but elevated the mean germination time and malondialdehyde concentration in winter wild oat seedlings. The lowest -amylase enzyme activity was noted at higher levels of extract application (1.1 nmol seed -1 min-2). Likewise, seedling weight, antioxidant enzyme activities and sucrose synthetesis enzymes activity were declined with sunflower extract application but malondialdehyde concentration increased. Menimum sucrose synthesis activity (1.36 nmol prot -1 min-2 ) and highest malondialdehyde concentration (0.96 nmol grfw-1) was noted at 20 grL-1 concentration of sunflower alcoholic extract application. In conclusion, sunflower alcoholic extract decreased seed germination, seedling growth, -amylase enzyme and sucrose synthetesis enzymes activity of winter wild oat.

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Because of water and soil salinity, there are many problems for turfgrass in Iran. use of salt tolerant native plants is one of the appropriate way for solving these problems. This study was undertaken to evaluate effect of four levels of salinity (less than2, 4, 8 and 16 ds/m) on morphological and physiological characteristics in naitive grass, Wheatgrass (Agropyron desertorum). The experiment was performed based on randomized complete block design with three replications. The results showed that salinity stress decreased turfgrass qualiy (TQ), fresh and dry weight of shoots and roots, relative water content (RWC) and root and shoot potassium contents. Also, salinity stress increased shoot and root sodium contents, electrolyte leakage (EL), proline contents and activity of enzymes. According to reduction in TQ and RWC and increase in EL under salinity stress, it seems that increasing in proline contents and enzymes activities could not be able to reduce the damage caused by stress. All of the measured parameters in this study showed the significant differences with control plant in 4 ds/m salinity level. The results showed the wheatgrass is salt-sensitive and salt tolerance it was less than 4 (ds/m).

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Heavy metal stress in plants may cause oxidative stresses and reactive oxygen species (ROS) production. To reduce this stress, plants use antioxidative defences, such as increasing the activity of antioxidant enzymes. In this study, the role of an arbuscular mycorrhizal (AM) fungi Glomus intraradices as a symbiotic microorganism with plant, was investigated in inducing tolerance to oxidative stress induced by Nickel heavy metal. Tall fescue plants were grown in soils containing 0, 30, 90, 180 ppm of Nickel, in two forms of infected to fungi (M+) and uninfected (M-) for 3 months. Experimental results showed that Nickel treatment caused reduction in growth parameters, where these parameter were higher in M+ plants than M- ones. Membrane electrolyte leakage was increased by the increase of Nickel concentration, and the increase was higher in M+ plants compared to M- plants. Results of measuring the activity of antioxidant enzymes showed that the presence of fungi had increased the activity of catalase (CAT), guaiacol peroxidase (GPX) and glutathione reductase (GR) enzymes against the toxic effect of Nickel, but this had not affected (increasing or decreasing) the activity of ascorbate peroxidase (APX) and superoxide dismutase (SOD) enzymes. These results demonstrated the negative effect on Glutathione-S-transferase (GST) enzyme. Precense of Glomus intraradices in M+ plants amplified the antioxidant system in Festuca plants and reduced the negative effects of Nickel treatment.

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5-aminolevulinic acid is the key precursor of all tetrapyrrole compounds such as heme, chlorophylls, bacteriochlorophyll, phytochrome and vitamin B12. In this study, the effect of 5-aminolevulinic acid, in reduction of salt stress in Lycopersicun esculentum Mill. var. Falcato were studied. Salinity at three levels (0, 50 and 75 mM NaCl) and ALA treatment at three levels (0, 1 and 2 mM) were investigated in this study. Salinity reduced growth parameters, phenolics content and phenylalanine ammonialyase activity, and increased lipid peroxidation, ion leakage and the activity of superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase and guaiacol peroxidase. 5-aminolevulinic acid application in two levels increased the growth parameters, phenolics content, and the activity of phenylalanine ammonialyase, superoxide dismutase, catalase, ascorbate peroxidase, glutathione reductase and guaiacol peroxidase, and decreased lipid peroxidation and ion leakage. These results show that the application of 5-aminolevulinic acid, via enhancing the activity of enzymatic antioxidant system, is effective in salt tolerance of tomato plants.

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Water deficit is one of the most important environmental stresses limiting plant growth and productivity around the world including Iran. Plants adapted to environmental stress with several strategies such as changes in antioxidant enzyme metabolism. Pennyroyal (Mentha pulegium L.) is an aromatic and medicinal plant of the Labiatae family that is widely used in traditional medicine. In this research, the effects of water deficit stress on growth, photosynthesis and antioxidant enzyme activities in leaf and root organs of M. pulegium plants were studied. Complete randomized block design have been used with four replications. Water deficit was studied at four field capacity levels (100, 75, 50 and 25%). Results showed that the growth, productivity and photosynthesis parameters significantly decreased under water deficit stress. Water deficit significantly increased the activity of antioxidant enzyme such as superoxide dismutase, peroxidase and ascorbate peroxidase in both organs, but the level of increase was more in roots than leaves of plant. Unlike to other enzymes, catalase activity decreased with the increase of water deficit levels, and highest activity was observed in leaves. It seems that pennyroyal plants can tolerate water deficit stress by dedicating less carbon source for growth, increase of antioxidant enzyme activity and regulation of antioxidant enzyme distribution in different organs.

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Today, soil and water contamination with heavy metals, such as cadmium (Cd), have been one of the important challenges for environment and human and plant health. Application of plant growth regulators such as Salicylic acid (SA) have been the proper option for mitigation of Cd impact on plant growth. The objective of this study was to evaluate the interaction of Cd and SA on antioxidant enzyme activity, leaf soluble protein and malondialdehyde of Safflower (Carthamus tinctorius L. cv. Soffe). This experiment was carried out as factorial based on CRD with four replications. Treatments included of four levels of cadmium nitrate (0, 25, 50 and 100 mg kg-1soil) and three levels of foliar application of Salicylic acid (0, 0.5 and 1 mM). Results showed that interaction of Cd and SA was significant for protein contents, catalase, proxidas, polyphenol oxidas and superoxide dismutase activity and malondyaldehyd. Increasing of Cd levels significantly increased the malondyaldehyd, catalase, proxidas, polyphenol oxidas and superoxide dismutase activity, but SA application inversed this trends. SA mitigates the detrimental effects of Cd and improved the physiological response of safflower under Cd stress.

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Nitric oxide (NO) has signaling property in plants, therefore the effect of nitroprusside (SNP) as an NO producing agent on viability in the cell culture, lipid peroxidation and activity of superoxide dismutase, catalase and peroxidase in the callus of Catharantus roseus was investigated. Cell suspension was prepared from callus of Catharantus roseus, and the cells were treated with 0, 10, 50, 100, 150, 200 and 250 μM of sodium nitroprusside for 1, 3 and 6 days to determined the cell viability(based on trypan blue staining as well as MTT colorimetric assay). Then using 100 and 200 mM of sodium nitroprusside as selected dose, the cell suspension was used to investigate the cell morphological changes. In addition the callus tissue was treated with the same dose to estimate the level of lipid peroxidation and the activity of superoxide dismutase, catalase and guaiacol peroxidase. Comparison of the data from trypan blue and MTT methods showed that the significant (p<0.05) differences in viability was concentration dependent with respect to control. Base on the morphology, SNP caused changes in the shape and size of the cell nuclei as well as disturbance in the chromatin. In addition changes in the cytoplasm such as shrinkage and cell border deform was observed in the treated cells compare to control. Also activity of the investigated enzymes following the oxidative stress increased significantly (p<0.05). The level of malondialdehyde as an indicator of lipid peroxidation also increased significantly. Sodium nitroprusside as an NO producing agent caused cellular membrane damage which results in cell viability reduction in the callus of catharantus roseus. Although the activity of the antioxidant enzymes increased significantly with respect to the oxidative stress but the produced cellular response was not able to compensate the damages.

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Water stress is one of the most important abiotic limiting factors that restricts growth, development and productivity of horticulrural crops. In vitro methods have been successfully used for evaluating water deficit stress in plants. In this regards, responses of four Iranian grapevine genotypes to drought stress induced by polyethylene glycol 6000 at -5, -5.24, -5.65, -6.24 and -7 bar were studied in Murashige and Skoog (MS) medium. Results indicated that drought stress reduced shoot fresh weight, leaf area, shoot length and leaf relative water content. Water deficit stress also caused significant increase in proline and malondialdehyde content, and activity of catalase antioxidant enzyme,. It seems that among studied genotypes , ‘Shahani’ with a greater capability to produce proline and antioxidant enzymes was more tolerant to drought stress and ‘Keshmeshi Ghermez Ghazvin’ and ‘Yaghuti Sefid’ genotypes were more susceptible and eventually ‘Asgari’genotype performed semi tolerance to water deficit stress.

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In this research the effect of four concentrations of nickel and copper (25, 50, 100, and 200 µM) on root and shoot length, fresh and dry weight, leaf surface, and photosynthetic pigments (Chlorophyll a, b and carotenoids), sugar, malondialdehyde, hydrogen peroxide content and antioxidant enzyme activity (CAT and APX) in Okra plants were evaluated. The results showed that in those plants which were treated with all concentrations of copper and nickel, the content of photosynthetic pigments and leaf surface were reduced significantly in comparison with control. In this investigation it was found that shoot and root length, dry weight and fresh weight of shoot and root which were treated with concentrations 50, 100, and 200 µM of cupper and 100 and 200 µM of nickel were reduced significantly when compared with the control. Content of soluble sugars in shoot and root plants which were treated with all concentrations of nickel and concentrations 50, 100, and 200 µM of cupper increased significantly in comparison with the control. Also, content of malondialdehyde, hydrogen peroxide content and antioxidant enzyme activity (CAT and APX) increased significantly in shoot and root plants which were treated with concentrations 50, 100, and 200 µM of copper and nickel when compared with control.

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To find out the biochemical and physiological responses of purple coneflower (Echinacea purpurea L.) medicinal plant to low temperature stress, a compeletly randomized design with three replications was conducted at Sari Agricultural Sciences and Natural Resources University in 2013. Five months old of coneflower seedlings exposure to three temperature levels of 23 ºC (control), 4 and 4 ºC for 6 h and then electrolyte leakage and malondialdehyde (MDA), enzyme activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX) and polyphenol oxidase (PPO), protein oxidation of the leaves, total phenols and flavonoids contents, percentage of DPPH free radical inhibition, as well as chlorophyll fluorescence parameters included F'm, F'v/F'm, qp, NPQ and ФPSII were determined. Results of experiment showed a significant increment of electrolyte leakage and malondialdehyde (MDA) content in leaves where the highest electrolyte leakage (55.7%) and MDA (12.3 nanomol/ g FW) were obtained at 4 ºC. In this study, the maximun activity of antioxidant enzymes (SOD, CAT and APX) were recorded when coneflower seedlings exposure to temperature lower than 4 ºC. Activity of POD and PPO enzymes, however, were decreased when temperature reduced to 4 ºC. The highest total protein content was calculated at 4 ºC that showes about 65% increment than control. Low temperature stress reduced total phenolic and flavonoid content of seedlings. Also, the highest antioxidant capacity of leaves (0.93%) were measures in control seedlings. No significant differences were observed between the fluorescence parameters in dark-adapted leaves. In light-adapted leaves, F'm and F'v/F'm content decreased with increasing stress and the highest content of the NPQ and qP were recorded at 4 ºC. Meanwhile, the lowest ФPSII was obtained at 4 ºC. In conclusion, it seems that the coneflower plant relatively had good tolerance to low temperature stress to 4 ºC.

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Basil (Ocimum basilicum) is a medicinal plant of the family of Lamiaceae. It contains phenylpropanoid and terpenoid componds. Chitosan with elicitor action induce defence mechanisms of plant. In the present study, the effect of chitosan on malondialdehyde (MDA), hydrogen peroxide (H2O2), gayacol peroxidase (GPX) , peroxidase (POD) and poly phenol oxidase (PPO) antioxidant enzymes activity, phenol compounds, flavonoids, antosyanin, chlorophyl a, b and carotenoid, soluble sugars and proline was evaluated. The plants were treated at pre flowering stage with 2 g/L chitosan and harvested after 1, 2, 3, and 5 days after chitosan. Comparing with control, the results showed that MDA and H2O2 increase in shoot in different harvest stages under treatment with chitosan. Also antioxidant enzymes activity, phenol compounds, flavonoids, antocyanin, chlorophyll a, b and carotenoid, soluble sugars and proline, in comparison with control , increased in many cases in different harvest steges. So it seems that chitosan, as a biotic elicitor, enhanced antioxidant enzymes activity and secondary metabolites production.

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Tuberosa (Polianthes tuberosa L.) is one of the most important cut flowers in Iran and word wide which the increment of postharvest life of this flower is very important. In this research proline as an antioxidant compound was used in 0(control), 1 and 10 micro molar concentrations and the effects of this compound on some morphological and physiological characteristics and vase life of tuberosa cut flower were investigated. The experiments were performed in a completely randomized design with 3 replicates. Results showed the significant effect of proline on vase life of tuberosa in both concentrations. The percentage of open flower increased in both proline concentrations. Finding showed the significant decrease in the wilted percentage of flower in both concentration of proline when compared with control flowers. The abscission percentage of flower also is very lower than the control flower. In according to the results, proline in both concentrations decreased the water loss and membrane leakage and the 10µM proline had the most effect. In flowers which were treated with proline, the activity of guaiacol peroxidase, catalase, ascorbate peroxidase and phenyalanine ammonialyase enzymes increased while the activity of polyphenol oxidase enzyme decreased. It seems that proline increment the postharvest life of tuberosa flower through the increase of antioxidant enzymes and decrease of polyphenol oxidase activity.

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.Salt stress is one of the major abiotic stresses especially in arid and semi-arid regions. This investigation was conducted to evaluate the effects of the salt stress on Ascorbate Peroxidase (APX) and Superoxide Dismutase (SOD) activities in safflower genotypes based in on a factorial experiment as a Completely Randomized Design (CRD) with three replications. The experimental factors were six genotypes of safflower (Arak, Isfahan, Khorasan, C111, AC-stirling and Saffire) and five levels of salinity (zero as control, 50, 100, 150 and 200Mm NaCl). There was a significant difference between genotypes in activity of SOD and APX enzymes under salt stress, with notable superiority of Isfahan genotype than other genotypes. Maximum activity of SOD was 99.16 uni/g Fw for Isfahan genotype in 150 Mm NaCl. In general, it seems that Isfahan genotype was more tolerant to salinity though, AC-stirling was the most sensitive genotype to salt stress. The results showed that Isfahan genotype had the greatest APX activity with 91unit/g FW although, AC-stirling had the lowest content with 58unit/g FW at control treatment. The activity of both enzymes increased with increasing salinity levels, which depended upon genotypes. APX and SOD activity decreased at 200 Mm NaCl concentration. APX and SOD activity decreased at the 200 Mm NaCl concentrations. Analysis of seedling traits showed that, the genotypes of Isfahan and Ac-sterling had the most and the least amounts of measured traits, respectively. In general, Isfahan genotype of safflower could be recommended in salt breeding programs.

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Water deficit is a common and major constrain for agricultural production in arid and semi-arid parts of the world like Iran, to the extent that it might threaten the nation’s food security in years to come. Seed germination is a crucial growth stage that is often affected by environmental stresses, including drought. This study investigated the effects of four levels of water potential (i.e. 0, -0.2, -0.4 and -0.6 MPa) on germination, seedling characteristics, soluble carbohydrates, proline and polyphenols contents, and antioxidant enzymes activities of 12 fennel genotypes. Low water potentials reduced germination percentage and speed of germination, seedling fresh and dry masses, shoot length and superoxide dismutase specific activity, though it led to increases in root length, soluble carbohydrates, proline and polyphenols contents, and catalase specific activity. The 12 genotypes according to the degree of decreases in germination percentage at -0.6 MPa compared to control, were classified into three groups, including drought-tolerant (Shiraz, Yazd, Kerman and Mashhad), moderately-tolerant (Hamadan, Kashan, Bushehr and Urmia) and drought-sensitive (Birjand, Ardabil, AviSina and Isfahan). Mashhad, as a drought-tolerant genotype, indicated the greatest germination percentage, seedling fresh and dry masses, root length, soluble carbohydrates, proline and polyphenols contents, and catalase and superoxide dismutase specific activities among 12 genotypes studied. The results obtained in this study demonstrate some key aspects of the drought tolerance-related characteristics of fennel at germination stage that may help elucidate the whole plant performance of fennel at drought-stricken areas, when integrated with results from field studies.

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Abstract Thioredoxins are invoved in redox regulation of many cellular processes. In this study the role of NADP+-Thioredoxin reductase C (NTRC) in the control of leaf senescence was investigated by biochemical characterization of Arabidopsis ntrc mutants. Forty days old wild type and two ntrc mutant lines were incubated either under normal dark-light or continous darkness regimes for 6 days as control and senescence treatment, respectively. Growth parameters, the contents of carbohydrates, pigments and the activity of some antioxidant enzymes were compared between wild type and ntrc mutant lines during dark induced senescence. Darkness led to decreased fresh and dry weights, chlorophylls and carotenoides, starch and protein contents in both wild type and mutant plants and there were no significant differences in the interactions of genotypes and treatments regarding to theses parameters. Darkness also induced the accumulation of anthocyanins, total and non-reducing sugars however, the accumulation of the carbohydrates in mutant lines was more pronounciated than wild type plants and again there were no significant differences in response of wild type and mutants to dark treatment. The activities of catalase, peroxidase and polyphenol oxidase of mutant lines were significantly greater than wild type plants. While darkness decreased the activities of ascorbate peroxidase and catalase it led to increased activities of peroxidase and polyphenol oxidase especially in the mutant lines. There were significant differences in the activities of all four enzymes between mutant and wild type plants in response to darkness. Thus, it appears that defects in NTRC mainly affects the activities of antioxidant enzymes rather than the other studied biochemical parameters of plants during the senescence process. This study might be useful in future breeding programs for controlling senecence process to achieve better performance of crop plants.