Proline dehydrogenase (ProDH; 1.5.99.8) belongs to superfamily of amino acid dehydrogenase, which plays a significant role in the metabolic pathway from Proline to glutamate. The goal of this research was gene cloning and characterization of ProDH enzyme from Pseudomonas fluorescens pf-5 strain.The gene encoding ProDH was isolated by means of PCR amplification and cloned in an IPTG inducible T7-based expression system. The Histidine-tagged recombinant enzyme was purified and its kinetic properties were studied.According to SDS-PAGE analysis ProDH revealed a MW of 40 kDa. TheK m and Vmax values of P. fluorescens ProDH were estimated to be 20 mM and 160 mmol/min, respectively. ProDH activity was stable at alkaline pH and the highest activity was observed at pH 8.5 and 30oC. This study is the first data on the isolation and production of P. fluorescens ProDH enzyme in E. coli expression system.

Background and objectives: Drought stress disturbs metabolic pathways in plant cells that leads to increase in reactive oxygen species (ROS) abundance. Plants have high efficient defensive system that prevents oxidative stress and can eliminate free radicals. Therefore high activity of antioxidant enzymes is essential for drought stress tolerance. Knowledge of antioxidant enzymes function and variation can be suitable marker to identification of morphological characteristics linked to this enzyme activities in plant breeding programs under drought conditions. Materials and methods: In order to study the effect of drought stress and endogenous treatment of Proline on the anti-oxidant enzymes superoxide dismutase (SOD), catalase (CAT), and peroxidase (POX), drought treatments (0,-4,-8 bar created by adding polyethylene glycol-6000) and 3 levels of Proline (0, 5, 10 mM) were applied on sunflower in seedling stage. This research was conducted in a factorial experiment based on completely randomized design, including 10 sunflower genotypes (in two susceptible and tolerant groups). Results: Based on the changes in Proline content and shoot dry weight, two inbred lines BGK 329 and RGK 221 were identified as the most susceptible and most sensitive among 10 inbred lines. Then, stripe pattern of enzymes was studied in 7. 5 percent horizontal acrylamide gel electrophoresis. Quantitate evaluation of activity of observed isozymes and statistical analysis of the data indicated that there is a significant difference among the activity of four enzymes SOD1, SOD2, CAT1, and POX1, out of all 7 enzymes. No significant change was observed in activity of isozyme SOD1 with increasing water stress and Proline levels. Interactions of genotype× Proline was significant (p<0. 05) for POX1 and SOD2. Drought stress had significant effect on isozyme CAT1 and interaction of stress× genotype affected the activity of isozyme SOD2. While the activity of isozyme POX1 was significant at stress× Proline interaction, the triple effect of triple stress× Proline× genotype was significant (p<0. 01) in the activity of isozyme POX1. SOD2 activity was largely influenced by the genotype so that at different levels of stress and Proline, some genotypes increased and some others showed decreased activity. The exogenous 5mM Proline treatment reduced the activity of isozyme POX1 and CAT1 under stress. Data analysis based on two susceptible and tolerant sunflower groups under drought stress showed that only POX1 activity was significant between the two groups and therefore. Conclusion: Proline as an important amino acid induces drought stress tolerance. An efficient antioxidant defensive system with inducible expression system to increase the accumulation of Proline have a vital role in the tolerance of drought stress environments. Isozyme of POX could be suggested to identify drought tolerant drought genotypes in seedling growth stage.

Salt stress is considered as one of the major limitations for food production especially in irrigated regions. The rice as a major food is very sensitive to salt stress. The comparison of physiological responses to salt in rice can be useful to improve resistance to this stress. For this purpose, in this study two Iranian rice cultivars with different resistances to salt stress namely, Khazar (salt sensitive) and Zayandehrood (salt tolerant) were examined. The seeds after sterilization were treated with different NaCl concentrations (0, 50, 100 and 200 mM) in Hoagland medium and germination percentage was determined. Then, the growth factors in 15 days-old seedlings and Proline content, catalase activity and Photosynthetic parameters were determined in 25 days old plantlets under 100 mM NaCl. The results showed that with increasing of salt concentration, germination percentage was significantly decreased in both cultivars but this effect was more drastic in Khazar. Salt stress (100 mM) reduced length, fresh and dry matter and also the relative water content of shoot in both cultivars. The results showed more accumulation of Proline in Zayandehrood than Khazar. The catalase activity was significantly increased in Zayandehrood by salinity but not in Khazar. Salt stress significantly decreased chlorophyll content in Zayandehrood but not in Khazar. Maximal quantum yield of PS II of rice leaves showed no significant difference for Zayandehrood but in Khazar, salt stress significantly decreased the ratio of Fv/Fm. It seemed that prolin content, catalase activity and Fv/Fm ratio playes essential roles in salt tolerance in rice.

Introduction and Objective: Arbuscular mycorrhizal fungi can improve salinity tolerance and plant productivity in saline-alkaline soils using different strategies including nutrient uptake, osmotic regulation, soil shaping, etc. Therefore, the use of arbuscular mycorrhizal fungi has been considered to reduce the effects of salinity. This study aimed to investigate the effect of arbuscular mycorrhizal fungus on the physiological, biochemical and caffeic acid levels of lemongrass (Cymbopogon citratus) under salt stress. Material and methods: The experiment was conducted as a factorial in the form of a completely randomized design in three replications. The experimental treatments included the first factor of arbuscular mycorrhizal fungi (inoculation and non-inoculation) and the second factor of salinity treatment at four levels (0, 50, 100 and 150 mM). The characteristics of photosynthetic pigments, ion leakage, Proline, soluble carbohydrates, flavonoid, anthocyanin, protein, ascorbate peroxidase, the amount of sodium and potassium ions and changes in caffeic acid content of lemon grass were investigated. Results: Plant inoculation with arbuscular fungus at salinity levels (150 mM) reduced ion leakage by 34.14% compared to the control. Plant inoculation with arbuscular fungus improved chlorophyll a, chlorophyll b, total chlorophyll and carotenoids by 118.51, 82.35, 50.70 and 98.64 percent, respectively, compared to its absence at salinity levels (150 mM). The results show that lemongrass plants against salt stress (150 mM) maintain the state of Proline, carbohydrate, flavonoid, anthocyanin, protein and ascorbate peroxidase enzyme activity in inoculation with arbuscular fungus at the rate of 20.48, 94.94, 27%, respectively. It increases by 27, 30 and 17.39% compared to the control (without inoculation). Also, the results showed that under the salinity stress of 150 mM and the presence of arbuscular fungus, the amount of potassium increased by 15.39% compared to the control; While the amount of sodium in the presence of this mushroom decreased by 8.46% compared to the control. Investigations showed that the percentage of caffeic acid in lemon grass inoculated with arbuscular mycorrhiza increased by 0.686% compared to control plants. Conclusion: This study suggests the potential use of mycorrhizal technology as a practical biotechnological approach to increase the growth and increase production of bioactive compounds of Cymbopogon citratus in salt-affected soils.

Objective Salinity is one of the most important stresses that reduce the yield of most plants. Plants use different mechanisms in response to environmental stresses. Chitosan and its oligomers are used in plants to resist abiotic stresses such as salinity. In this study, the effect of chitosan and salinity on gene expression and p5cs enzyme activity and Proline content in rapeseed was investigated. Materials and methods For this purpose, rapeseed plants were treated with sodium chloride solution (0, 50, 100 and 150 mM) and chitosan (0, 5 and 10 mg/l). The experiment was performed as a factorial experiment with a completely randomized design in 3 replications. Treated plants were harvested to measure gene expression, p5cs enzyme activity and Proline content. Results With increasing salt concentration, the expression of delta-1 Proline-5 carboxylate synthetase (P5CS) gene, enzyme activity and Proline content increased. In the combined salinity of 100 mM with chitosan 10 mg/l, gene expression, activity and Proline content in rapeseed had the highest amount. The use of chitosan in salt-containing medium compared to salinity treatments in same concentration, caused more P5CS gene to be expressed, increased enzyme activity and subsequently more Proline was synthesized. Therefore, there is a positive correlation between gene expression, enzyme activity and the amount of Proline produced. Conclusions According to the results, chitosan with a concentration of 10 mg / l in salinity treatment, by increasing gene expression and the activity of the enzyme delta-1-Proline-5-carboxylate synthetase (P5CS), produced Proline, which increases the plant's resistance to salinity stress.

Introduction: Salinity is of vital importance to present day agriculture, as rapid population growth especially in the developing world and consequently increased demand for agricultural products have made salinity oriented problems urgent. Salt stress reduces crop growth and yield in different ways. These primary effects of salinity stress causes secondary effects like reduced cell expansion, assimilate production and membrane function, as well as decreased cytosolic metabolism and production of reactive oxygen intermediates (ROS). Soybean is an important grain legume. The unique chemical composition of soybean has made it one of the most valuable agronomic crops worldwide. Its protein has great potential as a major source of dietary protein. In soybean, salinity stress inhibits seed germination and seedling growth, reduces nodulation, and decreases biomass accumulation and yield. Hormones are the biochemical language of living systems. Plant hormones have been defined as low molecular weight organic compounds governing physiological responses within plants, but distant from the sites of their synthesis. Exogenously applied, salicylic acid elicits several different physiological responses to stress and therefore increase plant resistance. For instance, SA was reported to improve resistance against salt strss in plant. Salinity stress reduced growth and protein content in Oryza sativa. This effect was, however, significantly reversed when Proline was exogenously supplied. Proline (Pro) functions as compatible solutes are up-regulated in plants under abiotic stress. They play an osmoprotective role in physiological responses. Furthermore, the salinity-induced inhibition of the antioxidative enzymes catalase and peroxidase was significantly overcome in Oryza sativa when Proline was supplied exogenously. Exogenous Proline application, besides enhancing the activity of antioxidative enzymes (CAT, POX and SOD), is also known to enhance the activity of other enzymes. Materials and methods: The present experiment was aimed to investigate the improvement of salt tolerance in soybean by exogenous application of Proline and salicylic acid as split plot arrangement in a randomized completely design in box with four replication in College of Agriculture, Shahrekord University in 2016. Main plot included three levels irrigation by saline water; 0 (control), 50 and 100 mM NaCl) and sub plot in four level of foliar applied (10 mM Proline, in combination with 10 mM Proline + 3 mM salicylic acid, 3 mM salicylic acid and sprayed with water (control)). Data were analyzed using SAS program and treatment means were compared by using L. S. D at 5% level. Results and discussion: The results revealed that Proline content, leaf POX, CAT and APX activities, H2O2, MDA contents, height and dry matter were significantly affected by salt level, Proline and salicylic acid applications and their interactions. The results revealed that effects exogenous application of Proline and salicylic acid were significant increase in activities of antioxidant enzymes, height and dry matter of soybean under salt stress. Furthermore, 100 mM NaCl with Proline and salicylic acid application decreased malondialdehyde and peroxide hydrogen 23 and 25% compared to water, respectively. So, interaction effects showed height and dry matter increased by Proline and salicylic acid application 32 and 38% under 100 mM NaCl compared to water, respectively. Also, the activities of CAT, POX, and APX in most cases increased under salt stress and Proline with salicylic acid application as compared to the 0 mM NaCl and without Proline and salicylic acid. Therefore, these findings showed that the exogenous application of Proline and salicylic acid has a vital role in the increase activation of antioxidant enzymes and resistance of soybean to salt stress. So in some works, here have been positive correlations between content of Proline and salicylic acid application and increasing activity of CAT, APX and POX enzymes to tolerance of plant to salt stress. The present study, therefore, suggests that exogenous Proline and salicylic acid improved tolerance to salt stress in soybean by increasing antioxidant defense system and decreasing membrane lipid peroxide.

Aromatic geranium is an ornamental plant whose essential oil is widely used in perfumery, health and cosmetic, food and pharmaceutical industries. In order to investigate the reduction of the adverse effects of low water stress in Aromatic Geranium (Pelargonium graveolens) plants by Proline and glutamine foliar application, a factorial experiment was conducted based on a completely randomized design with 3 replications in a commercial greenhouse located in Garmsar city in 1402-1403. The experiment was done in pots with 3 levels of low water stress (30, 70 and 100% of field capacity) and spraying with Proline and glutamine (each with two levels of 50 and 100 mg/liter) and their interaction. Low water stress was applied after the plant’s establishment and in the 6 to 8 leaf stage. Foliar spraying with Proline and glutamine at different levels was done in two stages. Finally, sampling and evaluation of traits was done about two weeks after the last spraying. The results showed that the highest fresh and dry weight of shoots (71.42 and 9.12 g), petals anthocyanin and total leaf chlorophyll (3.2761 and 16.4217 mg/g FW) and the lowest ionic leakage of the cell membrane (54.27%) were in glutamine 100 mg/L at 100% FC treatment. The highest root fresh and dry weight (16.35 and 3.67 g), the longest root length (45.28 cm), catalase, superoxide dismutase and peroxidase enzyme activity (8.23, 3.28 and 17.42 U E/g FW) and lowest Proline amount was obtained in Proline 100 mg/liter at 100% FC treatment. The longest shelf life of aromatic geranium flower on plant was (14 days) in glutamine 100 mg/liter at 100% FC treatment and the lowest (8 days) in control treatment at 30% FC. In total, Proline and glutamine with regulating osmotic pressure, inhibiting oxygen free radicals, and preventing membrane proteins and phospholipid degradation, caused a reduction low water stress negative effects in foliar-sprayed plants compared to the control in 70 and 30% FC. Therefore, it is possible to recommend Proline and glutamine foliar application under low water stress conditions to improve aromatic geranium (Pelargonium graveolens) growth, quality and flowering.

Triticum aestivum L. and Zea maize L. are both sensitive to salinity stress which is a major problem faced by farmers today. In the present study, the effect of chitosan, a biologic elicitor under salinity stress was examined on growth parameters and biochemical markers in maize and wheat seedlings. Seeds of wheat and maize plants were coated with chitosan 25%, 50%, and 75% solutions before they were planted and subjected to 0, 50, 100, 150, and 200 mM salinity stress under a 11/8 h photoperiod and at 25± 2 ° C temperature condition during 7 days. Then, the growth parameters including germination percentage, root and shoot growth as well as seedling weight were recorded. The biochemical markers including catalase and peroxidase activity and malondialdehyde, Proline, and protein contents were measured at day seven of the experiment. Significant difference in relation with growth parameters was observed at high concentrations of chitosan in comparison with the control plants under salt stress. Catalase and peroxidase activity and protein content increased under salinity stress and chitosan at high concentration reduced catalase and peroxidase activity. Salinity stress induced lipid peroxidation and malondialdehyde accumulation while chitosan reduced malondialdehyde content of the plants under salinity stress. The synthesis of protein was significantly increased with increasing the chitosan concentration. Generally, the growth parameters of both seedlings were improved and unfavorable effects of salinity were reduced when the seeds were coated with chitosan. Application of chitosan at low concentrations increased antioxidant enzyme activity and Proline content and decreased MDA accumulation. In conclusion, chitosan at an appropriate dose improved growth performance and biochemical marker fluctuation under salinity stress.

In recent decades cultivation of plants as a tool to manage the polluted areas by heavy metals has received an increased attention. In order to evaluate the possibility of using Four o’ clock plant as a phytoremediator in soils polluted by Cu and Pb, an experiment was conducted using four levels of Cu and Pb (0, 200, 400, and 800 mg/kg) concentrations, as a factorial experiment based on a completely random design in the Research Greenhouse of Shahid Bahonar University of Kerman, Iran. Results showed that pollution by each of these metals alters photosynthetic pigments concentration and morphological traits of plants. Stomatal characteristics were significantly decreased by these heavy metals. Significant increases were also found in concentration of reducing sugars and Proline, Pb and Cu accumulation in stems and roots and also activities of antioxidative enzymes. High levels of metal accumulation were found in roots. Compared to the control condition, plants which were grown under the highest levels of pollutions accumulated 32 and 22 times more Cu and Pb, respectively, in root tissue and 6 and 3. 6 times more in the shoot tissue. Superoxide dismutase, catalase and ascorbate peroxidase activities were also increased up to 2. 7, 2. 5 and 2. 4 times in plants grown in the soil polluted with the highest level of both metals. Meanwhile, Proline concentration increased 9 times in plants grown under the same conditions. These Results showed that this species can be used as a Cu and Pb tolerant ornamental plant in Cu and Pb polluted conditions.

One of the most important climate changes today is the decrease in precipitation. The present study was conducted to investigate the effect of drought stress on some physiological and biochemical characteristics of some promising grape cultivars. Experimental treatments included 5 Russian grape cultivars (Qazagiski Ramphi, Supran Bulgar, Muscat Yamtazini, Kishmish Hisrao, Besmiamphi Ramphi) and two Iranian cultivars (Chafteh and Soltan) and 3 drought levels (100 (control), 70 and 40% field capacity). A factorial completely randomized design with three replications was conducted in the greenhouse of Takestan Grape Research Station. After stress application, catalase, peroxidase, guaiacol peroxidase, ascorbic peroxidase, and hydrogen peroxidase enzymes activity, soluble sugar, total proteins, Proline, chlorophyll and leaf relative water content, leakage rate and membrane stability index were measured. Reducing the amount of irrigation water to 70 and 40% of relative field capacity significantly improved the activity of peroxidase, ascorbic peroxidase, hydrogen peroxidase, and guiocol peroxidase activity, and soluble sugar and Proline concentrations. Water shortage significantly reduced ion leakage, chlorophyll content, leaf relative water and the stability of grape leaf cell membrane. There were differences among different grape cultivars in response to stress. In general, Qazagiski Ramphi cultivar was more resistant to drought stress than other cultivars. Bidaneh Sefid and Besmiamphi Ramphi were the second and third cultivars in drought tolerance capacity, respectively.