جستجوی مقالات مرتبط با کلیدواژه « آنزیمهای آنتی اکسیدان » در نشریات گروه « زیست شناسی »

In this study, the effects of application of titanium dioxide nanoparticles under water deficit irrigation stress in the pre-flowering and grain filling stages on wheat were investigated. For this purpose, this plant was sprayed with %0.02 titanium dioxide in tillering and heading stages and some traits such as plant height, leaf area index, number of fertile tillers, number of seeds, 1000 seed weight, biological yield, harvest index, relative leaf water content, total chlorophyll content, proline and malondialdehyde content and ascorbate peroxidase as well as superoxide dismutase activity were examined. The results showed the positive effects of the application of these nanoparticles on the vegetative and reproductive growth of wheat under normal conditions and stress, so that under drought stress increased the number of fertile tillers, increased the number of seeds  and 1000 seed weight was compared with the non-application of nanoparticles under stress conditions.Under normal conditions and low irrigation stress, application of these nanoparticles during tillering had more favorable effects on vegetative and functional characteristics of the plant compared to the clustering time and increased wheat harvest index in drought conditions. On the other hand, the application of titanium nanoparticles effectively reduced the adverse effects of drought stress in the pre-flowering and grain filling periods whereas increased proline activity. Recent events have increased the ability of wheat to withstand drought stress.

Salinity stress is one of the important factors in decreasing the rate of growth and changing physiologic and metabolic processes of plants. In the present study to investigate the effect of salinity stress on physiological and biochemical performances and also gene expressions of Artemisia absinthium plant, an experiment was conducted with three level of salinity (0, 75, and 15 Mmol NaCl) in a completely randomized design with three replications under greenhouse conditions. Results showed that salinity stress decreased the rate of growth parameters in the plants including shoot length, root length, wet shoot weight, wet root weight, dry shoot weight, and dry root weight. Also, salinity decreased the levels of potassium, calcium, magnesium, and iron ions while increasing sodium levels in the plants. Increased salinity stress increased levels of proline, malondialdehyde, phenolic compounds, and activities of some antioxidant enzymes while it led to protein reduction in the plants under study. The expression of CYP71AV1 and ADS genes reduced to minimum at 150 Mmol and 75 Mmol NaCl treatments, respectively leading to reduced level of artemisinin in the Artemisia absinthium plants. According to the findings of this study, it might be argued that in its attempt to confront salinity stress induced fromsodium chloride, Artemisia absinthium employs the system of increased level of antioxidant enzymes activity, osmotic potential regulators, and phenolic compounds. Also, decreased expression of ADS gene can be an effective factor in reducing artemisinin contents in Artemisia absinthium.

Carrageenan and salicylic acid are bio stimulants that are involved in stress resistance by affecting the physiological and biochemical processes of the plant. In this study, carrageenan in two concentrations of 0.5 and 1 g / l and salicylic acid in 0.5 and 1mM concentrations were used for foliar application. This study was performed by factorial experiment in a completely randomized design with three replications. The pretreatments were applied in 6-leaf stage and the solutions were sprayed on the plant five times in the early morning in 10 days. One day after the last pretreatment, a number of pots were transferred to the refrigerator for 24 hours at a temperature of 5 °C for chilling stress, then the pots were returned to the greenhouse and after one day, samples of plant were collected from control and cold tressed pots. In this study, it was observed that pretreatment of plants with carrageenan and salicylic acid increased all growth parameters, osmolytes (include soluble sugars and proline), antioxidant enzymes include catalase, ascorbate peroxidase and guaiacol peroxidase activity, but reduced the oxidative stress index such as ion leakage, malondaldehyde and hydrogen peroxide content. The best results were obtained with the use of carrageenan 1 g / l and 0.5 mM salicylic acid. These results indicate that carrageenan and salicylic acid increased the resistance to cold stress in Impatiens flowers by increasing the protective parameters of the plant.It seems that these compounds as bio stimulants can be suitable for managing cold stress in other ornamental plants and can be used to reduce the chilling stress of autumn and winter in plants.

Tuberose flower is one of the aromatic bulbous flowers in tropical and subtropical regions. In order to study the effects of exogenous melatonin (M) on some physiological parameters of cut flower Tuberose, an experiment was performed base on a completely randomized design(CRD) with three replicates and 15 flower per replication. Melatonin (in concentrations of 0 and 250 μL.L-1 for 4 hours) was used as pulse-treatment. Melatonin treatment compared to the control prevented the decrease of Relative water content (RWC), the increase of Electrolyte leakage (EL), and malondialdehyde (MDA) concentrations in the tissues (leaves and petals). In addition, melatonin increased the amount of ascorbate peroxidase (APX) and peroxidase (POD) activities in the 6th day of storage compared to 3rd and 0th days. Peroxidase activity decreased in control treatment on 3rd and 6th days, respectively. While the activity of this enzyme was increased in melatonin treatment. The catalase (CAT) activity content of the tissues (leaves and petals) increased on 3rd day of storage and decreased on the 6th day. Therefore, it seems melatonin may help reduce oxidative stress and the lipids peroxidation and delays process of senescence in Tuberose flower.

Production of tolerant crop commercial varieties is very important due to increase of saline lands in Iran as is the case in the world. Therefore, this experiment was conducted to study germination, plant growth and probable tolerance mechanisms of Iranian sugar beet commercial varieties under salinity stress in two separate experiments during 2016. Sharif, Paya, Shokufa and Arya varieties were compared at 0, 4, 8 12 and 16 dS/m salinity levels in a factorial experiment based on completely randomized design with four replications to evaluate germination characteristics in the laboratory. Also, these varieties were compared in a similar experiment at 0, 4, 8, 12 ds/m salinity levels to evaluate physiological traits under greenhouse condition using randomized complete block design. Sharif and Paya varieties had better germination characteristics including seed germination, germination duration, root and seedlings length under 12 and 16 salinity stress levels than Shokufa and Arya as their germination percentage were 70, 60, 50 and 50, respectively. Antioxidant enzymes, chlorophyll content and relative water content of Sharif and Paya were higher than other varieties which caused higher seedling weights and stability of seedling number in these varieties under salinity condition.

Cadmium is an unnecessary heavy metal with a relatively high mobility in the soil-root system and the potential for toxicity in plants and humans. This research investigates the effects of cadmium chloride and its interaction with methyl jasmonate on cadmium accumulation, its relative water content, proline content, the amount of photosynthetic pigments and the activity of superoxide dismutase and catalase in wheat seedlings (Sivand cultivar). The results showed that cadmium accumulation in root and shoot at 300 μM increased 30 and 17 times, respectively, compared to control level. Cadmium at concentrations of 200 and 300 μM resulted in significant changes in the studied traits. So that activity of catalase and superoxide dismutase enzymes is increased 2 to 3 times and the amount of proline is increased by 15%. While chlorophyll a, chlorophyll b and carotenoid content dropped by between 20% and 30% and relative water content was about 3% lower than the control level. Results showed that 10 μM methyl jasmonate spray on plants under cadmium stress increased the amount of proline (16%) and photosynthetic pigments (23%) and decreased the cadmium content of the root and shoot by 30%. At the 100 μM of methyl jasmonate the activity of catalase and superoxide dismutase enzymes increased by 2 and 3 times, respectively. The results of this study indicate the ability of methyl jasmonate in change of cadmium accumulation in the root and shoot and in increase the activity of antioxidant enzymes.

Salinity is an abiotic stress that seriously constrains agricultural production including potatoes in most regions of the world. This study was carried out to investigate the effect of salicylic acid, on growth properties and biochemical characteristics of in vitro cultureof Solanum tuberosum cv. Agria under salinity stress. The study was carried out at a completely random design with eight replications in the Department of Horticulture of University of Tabriz. Variables under study included salinity stress at two levels (0 and 70 mM/L sodium chloride) and salicylic acid at four levels (0, 1, 10, and 100 mM/L). Results showed that salicylic acid significantly mitigated the effects of salinity. Therefore, the highest plantlet length was recorded under salinity along with 10 mM salicylic acid treatment showing the positive effect of the treatment on mitigating the influences of salinity. However, the concentrations of salicylic acid higher than 10mM/L not only had no effect on plants, but also negatively influenced the effects of salinity stress. Also, antioxidant enzyme activity of the plantlets had a considerable increase at all concentrations of salicylic acid and levels of salinity. Moreover, the study suggested that Solanum tuberosum cv. Agria was relatively sensitive to salinity stress and all characteristics of the plants under study were influenced with salinity. Also, application of salicylic acid caused improvement in the growth and biochemical properties of the plants under study increasing their tolerance against salinity stress.

In this research, the effect of pretreatment of seeds with arginine (amino acid precursor of nitric oxide and polyamine) on growth parameter, Kﳖ ratio and reduction of oxidative damages induced by salinity (300 mM) were investigated in wheat plant.. Results showed that salinity stress had no significant effect on growth parameters while increased the total oxidative stress index such as lipid peroxidation hydrogen peroxide content and antioxidant enzymes activity. Saking of seeds in arginine (0.5 mM) for 24 hours, reduced the lipid peroxidation and hydrogen peroxide in plants which were under stress. In plants which were under salt stress, pretreatment of seeds with arginine also increased the activity of root and shoot GPX and shoot APX enzymes when compared with non pretreated plants. In this research the K /Na ratio decreased under salt stress and arginine pretreatment increased this ration in plants. According to the protective role of some arginine metabolism compouns such as nitric oxide and polyamines that report in previous study,in this research it seems that arginie caused increasing salt tolerance directly or indirectly throuth some compounds such as nitric oxid and polyamines production

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.

In this experiment، we studied the effects of drought stress under field conditions on chlorophyll a، chlorophyll b، carotenoids، rubisco large subunit (rbsl) and the activities of antioxidant enzymes in barley at early anthesis، watery ripe، late milk and soft dough stages of two genotypes with different yield (Q13:1390 Kg/ha and Q20:1582 Kg/ha). The results showed that under oxidative stress chlorophyll b is more sensitive than chlorophyll a. The amount of cartenoids increased at initial time of stress period، but declined with the progress of stress. The amount of rbsl declined during senescence and drought stress. The activity of SOD declined with plant age in both water treatments. However it was more in plants under drought stress of Q13. APX activity declined with age in both water treatments of Q13. There were no significant difference with age in Q20 APX activity. Drought stress triggered increases in antioxidant enzymes activities. We concluded that Q20 has more ability to maintain SOD activity during water deficit stress and APX activity during senescence; therefore it seems that this ability is a key role for increasing the yield of Q20 in compare to Q13.

The effects of pretreatment of Salicylic acid on wheat seed germination (Triticum aestivum L. cvs. Roshan), lipids peroxidation, superoxide dismutase (SOD), catalase (CAT), polyphenol oxidase (PPO) peroxidase (POX) activity in salt stress condition was investigated. Treatments of wheat seedlings with different concentrations of salicylic acid (SA) for seedling growth (0, 0.5, 1mM) have been used. Salt stress was inducted by NaCl solution (0, 50 100, 200 mM). For this purpose after surface sterilization of seeds, they were soaked in SA solutions for 24 h and then dried by sterile paper then transferred in to sterile petri dishes and added 10 ml NaCl solution with different concentrations. After one week number of germinated seed, radical length, seedling length and dry weight were recorded. Antioxidant enzymes activity and lipid peroxidation were assayed too. The results showed salinity decreased seed germination. Thus, high concentration of NaCl (200mM) decreased germination 17/6% than control treatment. Influence of SA was significant and increased percent of germination in stressed and control treatments. SA increased the level of cell division of seedlings and roots which caused an increase in plant growth. Enzymes assay showed, enzyme activity was increased in salt stress conditions and SA reduced activity of antioxidant enzyme. In brief, the SA treatment reduced the damaging action of salinity on seedling growth and accelerated a restoration of growth processes.