جستجوی مقالات مرتبط با کلیدواژه « تنش آبی » در نشریات گروه « زیست شناسی »

Water stress is one of the most important factors affecting the metabolic pathways in the plant and thus alters the synthesis and accumulation of natural compounds such as fatty acids and hydrocarbons in medicinal plants. This study aimed to investigate the effect of different levels of water stress (Full irrigation at field capacity, irrigation at 70% of field capacity and irrigation at 40% of field capacity) on fatty acid and hydrocarbon quantities of Milk thistle. Drought stress was applied at flowering stage. Then the oil extract was extracted from the seeds using Soxhlet method and analyzed by GC-MS. Information about the pathway of the reactions of the identified compounds was extracted from bioinformatics databases. The results showed that the yield of fatty acids and hydrocarbons increased with increasing drought stress intensity. The predominant fatty acids identified in Milk thistle oil extract was linoleic acid (15.2-27.4%) and its dominant hydrocarbon was dodecane (12.3-14.1%). The percentage of fatty acids detected under stress was reduced, probably due to their degradation into hydrocarbons to maintain osmotic pressure under dehydration.

Arbuscular mycorrhizas are able to reduce the adverse effects of biotic and abiotic stresses on crops. To investigate the effect of inoculation with Glomus mosseae on physiological characteristics of two rice cultivars under water deficit conditions, an experiment was conducted in a randomized complete block design in the greenhouse. Irrigation conditions included flooding, stop irrigation up to 70% and 50% of field capacity. In general, in both groups of plants, inoculated and control plants (non-inoculated), increased levels of phenol, tannin, glycine and betaine, as well as polyphenol oxidase and guaiacol peroxidase enzymes were observed under water deficit conditions. However, the change amount of each trait in inoculated plants was significantly higher than the non-inoculated plants. In case of stopped irrigation up to 70% of field capacity, the amount of proline, antioxidant enzymes in Nemat cultivar was higher than Tarom Hashemi, while Glycine betaine, tannin and phenol content was higher in Tarom Hashemi than Nemat cultivar. In case of stopped irrigation up to 50% of field capacity, the amount of phenol, tannin, glycine and betaine as well as antioxidant enzymes in Nemat cultivar was higher than Tarom Hashemi, which can be a reason for different effects of arbuscular mycorrhizal colonization on the response of rice cultivars to water deficit conditions. Based on the results, it seems that inoculation of rice plant with mycorrhizal fungus can play a role in reducing the adverse effects of water deficit in case of water shortage conditions during the critical stages of plant growth.

In this study, the effects of drought on some physiological characteristics of winter and spring leaves of jasmin (Jasminum fruticans L.) were examined in plants grown in pots and treated with or without water stress for 25 days. Our results showed significant difference in pigment content and phenolic metabolism between winter and spring leaves of jasmine during spring season. In this study, winter leaves showed the higher Chlb, carotanoids, total phenol, flavonoids as well as phenylalanine ammonia lyase (PAL) activity, and relative water content (RWC) as compared to spring leaves, indicating winter leaves are sufficient in their capacity for non-photochemical energy dissipation via these mechanisms. However, water stress did not significantly affect these parameters. Drought significantly increased the amount of malondoialdehyde (MDA) and hydrogen peroxide (H2O2) following significant enhancement of peroxidase (POD) activity. However, in winter and spring leaves treated with water stress, decrease in the maximal quantum efficiency of PSII (Fv/Fm) was not statistically significant. In contrary, spring leaves exhibited a significant decrease in the performance index (PIabs) parameter under drought conditions. Notably, the kinetics of the OJIP chlorophyll fluorescence curve exhibited a quicker difference between winter and spring leaves of jasmine under well watered conditions. Thus, photosynthetic apparatus of winter leaves maintained a higher PIabs during spring season, and showed more tolerance to water stress by dissipating excess light energy by carotenoids; and by screening of photoradiation by phenolic compounds.

Drought is one of the abiotic stresses that limit plant growth and crop production. Salicylic acid is one of growth regulators plays an important role in biotic and abiotic stresses.  In this study the effect of salicylic acid on reduction of drought stress in safflower (Carthamus tinctorius L.) were studied. The effect of the concentrations of SA (0, 0.25 mM) and water stress (levels 100%, 75%, 50% and 25% FC) on antioxidant enzymes activities and expression of the SOD gene were studied. When plants had three expanded leaves, they were sprayed with SA and after 2 days, ther were exposed to drought. After seven days, plants again were sprayed by SA. After two weeks plants were harvested for studying of physiological and molecular parameters. The results showed that drought stress 25%FC increased leaves and roots antioxidant enzyme activity, H2O2 and malondialdehyde contents, leaf Mn-SOD and leaf and root Fe-SOD. Interaction of SA and drought increased root antioxidant enzyme activity and reduced leaf antioxidant enzyme activity, root and  leaf gene expression of Fe-SOD and Mn-SOD, leaf and  root  H2O2 and  malondialdehyde contents  . As a result, salicylic acid had a significant role in the reduction of damage of drought stress in safflower plants

Trees in the landscape always lost their vitality for various reasons, and decline or dieback are experiencing. One of the factors that can affect the decline of trees can be pointed to drought stress. This study was conducted to evaluate the effects of inoculation with mycorrhizal fungi (Rhizophagus intraradices and Funneliformis mosseae inoculated, and the combination of both species) and growth promoting bacteria; Pseudomonas Flourescens on growth responses of Cupressus arizonica in experiencing stress induced by a deficit of water as a factorial experiment based on completely randomized design, with 3 replications. In this study, the Interactions between fungi, bacteria and deficit irrigation on the concentration of phosphorus and iron, ion leakage, proline content and shoot dry weigh were significant. Under deficit irrigation most of the treatments such as colonization rate (by 39%), phosphorus (by 33%), potassium (by 16%) and iron (by 25%) cocentration, relative water content (by 25%), chlorophyll content (by 76%), height (by 29%), shoot dry weight (by 41%) and the Cupressus vitality (by 35%)  decreased; on the contrary, the percentage of electrolyt leakage (by 36%) and proline content (by 122%) increased. Morever, inoculation with mycorrhizal fungus increased the concentration of phosphorus and iron, relative water content, chlorophyll content, height, shoot dry weight and However reduced ion leakage and proline content and lead to improvement of plants growth and vitality. The presence of Pseudomonas alone did not have a significant role in improving the growth of plants under water stress conditions, but its interaction with mycorrhizal fungus showed positive effects. In general the results of this experiment showed that inoculation of cupressus plant with mycorrhizal fungus with the use of P. florescent bacteria can have a positive effect on the survival of this plant under water stress conditions.

This experiment had been carried out to evaluate the potential of mycorrhiza fungus on growth rate and performance of plantlets derived minituber in water deficiency condition. The test was conducted in a factorial experiment based on completely randomized design with four replications. The factors included four level irrigation regimes (100%, 85%, 75% and 65% of water field capacity), inoculation of potato minituber by mycorrhiza sp. Glomus intraradices and non-inoculated ones. Growth indices such as stem length and diameter, internode number and length, stem and root fresh weight, leaf area and chlorophyll content were measured. Analysis of variance showed that the main effect of mycorrhiza and water irrigation regimes had significant effect by probability of 1% α level on stem length, leaf area, chlorophyll content, colonization percentage, fresh and dry stem weight, fresh and dry root weight and number of minituber. Interaction effect of two factors was significant only in leaf area, chlorophyll content and dry root weight. By mean comparisons demonstrated that the highest internode and stem length, fresh and dry stem weight, fresh root weight, leaf area and chlorophyll content were accomplished in mycorrhizal inoculation with 85% FC providing water. Totally, the results demonstrated that mycorrhization of minituber in two lower water available levels produce plantlets that had same situations as compared with non-inoculated of 100% FC providing water.

Abstract Plants are frequently and naturally exposed by different of biotic and abiotic stresses including drought have negative effects on plant growth and yield. Symbiosis with mycorrhizal fungi is the broadest plant strategy for acclimation to environmental stresses. Hence in present study interaction of endomycorrhizal fungus and Pseudomonas aeroginosa, as Mycorrhizal fungi with Rhizobium meliloti in completely randomized blocks under three levels of irrigation and three replications wave examined. Spores of native endomycorrhizal fungus symbiont with medicago from Bagherabad region in Kerman are propagated by Zea mays and then used with mycorrhizal spores, Pseudomonas and Rhizobium separately and together in pots for three months under 3 different levels of irrigation, 70, 50, 20 persentage of field capacity. Results showed reduction of protein content but proline and reducing sugars concentration increased significantly under water stress. Changes in total nitrogen concentration were not significant. Inoculation with endomycorrhiza and bacteria significantly enhanced protein, proline, reducing sugars and nitrogen concentration under stress and without stress in comparison to control. In addition to, endomycorrhiza and bacteria had synergistic effect so that in many cases coinculation were more effective in relation to single inoculation. On the basis of these results, coinoculation with endomycorrhizal fungus, Pseudomonas aeroginosa and Rhizobium meliloti is suggested for increasing medicago tolerant to water stress.

The responses of plant roots play an important role in stress tolerance and optimal use of the moisture stored in the soil. Study of the most important morpho-physiological and biochemical parameters of roots can be an appropriate approach for selection of the cultivars tolerant to moisture stress. This study was conducted in pots and as a factorial completely randomized design in three replications.Treatments consisted of lentil cultivars (Gachsaran, Kimiya, Ziba, and Robat) and moisture stress at four levels: 25%, 50%, 75% and 100% field capacity. Results showed that the interactions between lentil cultivars and water stress on all root traits were significant. Under severe moisture stress, Rabat and Gachsaran cultivars were significantly superior to the Kimia and Ziba cultivars in most of the studied traits such as root length, root area, concentration of K, concentration of Ca, proline content, protein content, POX activity, and SOD activity. Kimia cultivar compared to other cultivars in all stress levels had the lowest root morpho-physiological and biochemical characteristics. The findings of this study showed that in comparison with other cultivars, Robat and Gachsaran were affected less under moisture stress, by means of applying effective stress-tolerance mechanisms such as more antioxidant enzyme activity, more root proline and protein contents, increased root length and area, more K and Ca absorption. According to the results of this study, Robat and Gachsaran cultivars are introduced as tolerant cultivars for cultivation under moisture stress.

Ion balance and osmotic regulation in plants to mitigate the effects of drought is possible with accumulation of osmolytes like proline and glycine betaine. Accordingly، in order to investigate the effect of mycorrhizal fungai species on the eco-physiological characteristics of hyssop، a factorial experimental based on randomized complete block design with three replications was conducted at the Research Farm of Agriculture and Natural Resources of West Azarbaijan in 2013. Experimental treatments included species of mycorrhizal fungi (Glomus mosseae، G. intraradices، G. fasiculatum، G. claroideum، Acaulospora longula and control without mycorrhiza) and four levels of irrigation (irrigation at 80، 70، 60 and 50% of field capacity). The results of ANOVA showed the significant interaction between water deficit and mycorrhizal fungi species on the concentrations of malondialdehyde (MDA)، glycine betaine، proline، total soluble carbohydrates and essential oil percent. The highest concentrations of malondialdehyde (MDA) (125 nmol/g fresh weight)، glycine betaine (2019 μm/g dry weight)، proline (111 μm/g fresh weight)، essential oil percentage (7. 29%) and total soluble carbohydrates (396. 7 mg/g dry weight) were obtained from plants inoculated by G. claroideum، A. longula، A. longula، G. fasiculatum and G. claroideum and irrigated at 50 and 60% field capacity، respectively. The concentration of malondialdehyde (MDA) biomarker was increased at non-mycorrhizal plants compared with mycorrhizal one. Overall، this study suggested that the mycorrhizal species were effective to reduce stress and water use efficiency.

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.

Different cultivars of one species activate various enzymes such as superoxide dismutase, catalase, peroxidase, glutathione reductase and ascorbate peroxidase in order to defense against the water stress.These enzymes have important role in plant defense against the reactive oxygene species. In this study, behavior different of peroxidase, ascorbate peroxidase and catalase and effects of water stress on activity of them against drought and flooding were investigated in two soybean cultivars (Glycine max L. cv. Pershing and cv. DPX). An experiment was carried out under potting conditions and 4 treatments (20, 40, 60 and 80% of water saturation capacity) were used. Antioxidant enzymes indicated differences with stress and organ. Peroxidase activity increased in nodule and root under drought and flooding stress but in leaf, peroxidase activity increased in lower water contents (20 and 40%) and in DPX, significant difference did not shown in the all. In both studied organs, catalase activity increased in flooding and drought, in DPX and Pershing, repectively but significant difference did not shown in other treatment. In the leaf, ascorbate peroxidase activity decreased with decreasing in irrigation but in root, its activity indicated significant increaseing in flooding and drought, in DPX and Pershing, repectively. Results indicated that enzymetic activity can vary by cultivar, stress and organ type, too.

Water stress is the main limitation in the production of many crops and causes many physiological and morphological reactions in plants. This problem has been observed in different cultivars of the same species, including soybeans. The aim of this research was to study the effect of water stress on water relations, proline content and morphological characteristics of two soybean cultivars including Pershing and DPX. For this purpose, an experiment was carried out in pots and water treatments of 80 (flooded), 60, 40 and 20% (dry) of the water saturation capacity of the soil were applied on them. The results of the studies showed a significant difference in the measured measurements in two soybean cultivars. In both cultivars, reducing the amount of irrigation caused a decrease in plant height and root length, and in the flooding treatment, it was associated with a significant increase in misplaced roots. In the Pershing variety, the decrease in the amount of irrigation led to a decrease in the relative amount of water (RWC), but in the DPX variety, the lowest amount of RWC was observed in the 40% treatment. Leaf water loss (LWL) was higher in all treatments in Pershing variety than similar treatments in DPX variety. The highest amount of proline in leaves and roots was related to treatments with lower RWC, which was observed in Pershing and DPX cultivars in 20% and 40% treatments, respectively. In both cultivars, the amount of proline amino acid was higher in the leaves than in the root. The results showed that in both cultivars, leaves were more affected by water stress than roots, and Pershing cultivar showed more sensitivity in low water levels.