جستجوی مقالات مرتبط با کلیدواژه "تنش اکسیداتیو" در نشریات گروه "بیوتکنولوژی و ژنتیک گیاهی"

Cold stress is one of the major factors limiting rice (Oryza sativa L.) productivity and yield. Two rice cultivars were chosen for this study: a japonica rice, ‘Gerde’, and an indica rice, ‘Shiroodi’, representing tolerant and sensitive cultivars, respectively. In this work, the early physiological and molecular responses of these two cultivars to 4°C cold stress were investigated. We found that cold stress caused a significant decrease in the content of chlorophyll a, chlorophyll b, and carotenoids in both rice cultivars. However, the photosynthetic pigment content in the Shiroodi cultivar decreased to a greater extent, indicating its limited genetic capacity to protect its photosynthetic machinery. During cold stress, the amounts of hydrogen peroxide and malondialdehyde produced by the Shiroodi cultivar were significantly higher than those in Gerde, suggesting a lower capacity of Shiroodi to scavenge reactive oxygen species. The higher level of beta-glucosidase gene expression in the final hours of cold treatment in the Gerde cultivar indicates the involvement of this enzyme in elevating cellular levels of active abscisic acid. Moreover, the significant increase observed in the transcript level of phenylalanine-ammonia-lyase in Gerde indicates the induction of defense responses related to the phenylpropanoid pathway. Altogether, one can conclude that the higher cold tolerance of the Gerde cultivar is multifaceted, involving various factors such as its ability to protect its photosynthetic machinery, its greater capacity for cell protection against oxidative stress, and the expression modulation of genes involved in abscisic acid metabolism and secondary metabolism.

Reactive oxygen species (ROS) produced in organelles such as mitochondria, chloroplast, and peroxisome play an important role in plant signaling and signal transduction pathways. ROSs basically are able to regulate oxidation-reduction (known as redux) reactions, plant growth and defense responses to environmental stimuli. Therefore, they affect every aspect at all life cycle stages of plants. ROSs such as hydrogen peroxide, superoxide, hydroxyl radicals, and singlet oxygen act as secondary messengers in plant cells to regulate a diverse range of protein functions (with post-translational modifications) and gene expression. They are produced naturally during the plant responses to environmental conditions and intra-/inter-cellular communications. Recent researches are indicating that ROS compounds play a key role in the plants response under both biotic and abiotic stresses. Biotic stresses such as fungi, viruses, mites, insects and other organisms, along with abiotic stresses such as drought, salinity and heavy metals, increase the production of ROS in plant cells. Plants possess various mechanisms to deal with the destructive effects of ROS increased production. ROS removal in plants is usually performed by two main groups of enzymatic and non-enzymatic antioxidant molecules. Antioxidant molecules play important roles in plant tolerance under stressful conditions by neutralizing ROS and converting them into water molecules. However, under severe stress conditions, plants are not able to eliminate the entire content of extra produced ROS molecules; as a result, the high amount of ROS causes oxidative stress in plants leading to various damages to the main components of the cells, such as proteins, lipids, DNA, carbohydrates, and ultimately cell death. There are still many unanswered questions regarding the plant specific responses to oxidative stress and regulation of cell communication during stress conditions. This review article tries to introduce the origin, location, and pathways of ROS production along with their types and effects on the cellular signal transduction system in stimulating adaptive responses of plants under stress conditions. Moreover, this review discusses the effectiveness of antioxidants systems in maintaining cell homeostasis and neutralizing the negative impacts of oxygen free radicals in plants.

Environmental stresses have an irreversible effect on the production of bread wheat (Triticum aestivum L.), one of the most important crop plants. On the other hand, AP2/ERF members are the most important transcriptional regulators that influence plant growth and response to biotic and abiotic stresses. To evaluate the mechanism of salt stress tolerance in wheat the activities of superoxide dismutase, ascorbate peroxidase and catalase in two tolerant wheat landraces (3623 and 3625) under salinity were investigated by completely randomized factorial experiment at control and 250 mM salinity in three replications. Seedlings were sampled at 0, 1, 3, 6, 12 and 24 h and 10 days after stress. The activity of enzymes was measured in the root and shoot of plants. The AP2-21 nucleotide sequence was extracted from the NCBI database and primers were designed and the gene fragment was isolated from wheat and then cloned and sequenced and confirmed by the presence of AP2 conserved domain. TaAP2-21 expression was evaluated by qPCR using specific primers and β-actin housekeeping genes. The results showed a significant difference in enzyme activity at different times compared to control in both tissues of both landraces and the highest was observed in short and medium-term stresses, however, apparently in long term stress the antioxidant mechanism of the enzymes is more active in 3623 than in 3625. Gene expression decreased significantly under salinity in both tissues. The TaAP2-21 gene is probably one of the inhibitors of the transcription of saline responsive genes and causes salt sensitivity in wheat.

Cucumber mosaic virus (CMV) is one of the most important viruses which causes yield reduction in tomato. In this experiment, the role of salicylic and jasmonic acids was investigated in the gene expression of antioxidant enzymes and induction of resistance to oxidative stress due to CMV inoculation in tomato (Falat cultivar). Results showed that in control plants expression of genes encoding catalase (CAT) and peroxidase (POX) enzymes gradually decreased to 15 days post inoculation (dpi), but expression of superoxide dismutase encoding gene (SOD) was increased at 15 dpi. In CMV inoculated plants, CAT gene was down-regulated, but POX gene was up-regulated to 8 dpi. SOD gene expression also increased in CMV inoculated plants to 15 dpi. The highest expression rate of POX observed at 15 dpi in SA treated plants which was 120% greater than before hormone application. Hormone application decreased the disease severity and symptoms to 80%. In Falat cultivar, peroxidase role in scavenging of H2O2 was greater than catalase and in order to inducing resistance, we can use SA and JA just before virus infection.

Cadmium is a heavy metal causing oxidative stress in plants. The study objective was to determine phytoremediation potential of black nightshade in cadmium contaminated culture medium. The experiment was carried out under hydroponic conditions with five cadmium chloride concentrations of 0, 100, 200, 400 and 600 mM based on completely randomized design in three replications. Root length, plant height, plant fresh and dry weight, leaf area, cadmium uptake rate and total chlorophyll were recorded. Cadmium application decreased plant dry weight, leaf area and total chlorophyll and increased root length, plant height and cadmium uptake. Cadmium concentrations up to 400 mM caused cadmium uptake increment in plants. Black nightshade kept phytoremediation potential even at 600 mM cadmium concentration. These changes in morph-physiological traits are for cadmium stress management causing survivability of plant against these conditions and black nightshade could be effective in environment hygiene by cadmium accumulation in its tissues. Therefore, black nightshade might be recommended as a cadmium hyper-accumulator plant in industrial cadmium contaminated soils.

GTP cyclohydrolase I (gtpch I, EC 3.5.4.16) catalyzes the conversion of GTP to dihydroneopterin triphosphate and formic acid through a complex series of reactions. This reaction is the first committed step in the biosynthesis of FH4 (tetrahydrofolate) in plants and certain microorganisms, and BH4 (tetrahydrobiopterin) in mammals. Folates are comprised of a pABA (p-aminobenzoate) unit condensed with a pterin ring derived from GTP and a variable number of glutamate moieties. The expression analysis of a gtpch I gene was studied under abiotic and oxidative stress conditions in grape (Vitis vinifera L. cv. Askari) leaf by Semi-quantitative RT-PCR. The grape gtpch I gene was found to be differentially induced under abiotic stress conditions. The transcript level of Vvgtpch I was decrease under abiotic stress conditions such as drought, salt, and heat. Under diamide, AlCl3, ABA, and SA treatments, it was also decreased the transcripts amount of Vvgtpch I, whereas its expression was increased under H2O2, CuSO4, CdCl3, and CoCl2.

Salinity is one of the most important environmental factors that limits the growth and production of plants around the world. The identification and use of compounds that can increase the tolerance of plants against environmental stresses such as salinity are important from a theoretical and practical perspective. Methyl jasmonate is one of the known plant hormones that reduces the harmful effects of stress. In this study, the effect of seed pretreatment with methyl jasmonate for six days at three concentrations (0, 5, & 10 μM ) on the enhancement of salt tolerance at three levels (0, 50, & 100 mM NaCl) of Garden cress seedlings was examined. Salt stress reduced the germination and growth of cress while the amount of hydrogen peroxide, lipid peroxidation, and the activities of APX and GPX dramatically increased. Pretreatment of Garden cress seedlings with methyl jasmonate had no significant effect on the activity of GPX, while it obviously reduced the content of hydrogen peroxide and malondialdehyde, and significantly increased the root growth and the activity of APX. By activating enzymatic antioxidant defensive system, the use of methyl jasmonate increases the resistance of plants to oxidative stress caused by salinity and drought. Since these enzymes play an important role in protecting cells, especially photosynthetic apparatus, by removing oxygen free radicals, the positive effects of methyl jasmonate pretreatment performance in increasing maintenance of the membrane correlation and improvement growth is reflected in this study.

Arabidopsis mutant old3 (Onset of Leaf Death3) has a EMS mutation in Cysteine synthase gene(AT4G14880). One of the important functions of this gene is plant detoxification against oxidative stress. Old3 plants exposed to cadmium go through plant cell death after 12 days at 22˚C. Since the growth and development of old3 plants return to a normal situation at 28˚C, this research was performed to evaluate old3 plant responses to cadmium at 28˚C and 22˚C and compared with the wild type plants, Landsberg erecta (Ler-0). Therefore several traits including germination rates, growth rates and fresh weights were studied. POD and CAT enzyme activities were assayed in mutant seedlings. In addition, the relative expression levels of two marker genes, DEFL and GST1, which are involved in oxidative stress was measured. Factorial statistical design based on a completely randomized design was used to analyze the data. The plants growth, fresh weight and germination rate under the cadmium stress at 28˚C were higher than those under 22˚C, and it happened more clearly in the mutant plants. The result suggested that the resistance of wild type was higher at both two 28˚C and 22˚C. The investigation of POD enzyme activity at 28˚C indicated higher activity in the mutant plants compare to wild type. Furthermore, the relative expression levels of DEFL and GST1 genes in the mutant old3 plants were enormously higher than those of wild type at 28˚C. As a result, it was found that although the growth and development of old3 plants could be recovered by the temperatures, but the mutant old3 plants were more sensitive to the cadmium contamination compared to the wild type Ler-0 plants at both temperature and could not be recovered into the wild type responses at 28˚C.

The growth and development of plants under biotic and abiotic stresses is always accompanied with accumulation of various reactive oxygen species (ROS) molecules. Higher levels of ROS can be harmful leading to oxidative stress-induced leaf death. In addition, chemical materials such as Aminoteriazole (AT) can cause oxidative stress by suppression of catalase activity. RON1/SAL1 gene is one of the environmental stress responsive genes in Arabidopsis encoding the polyphosphate 1-phosphatase enzyme. Most of available mutations in RON1 are accompanied with changes in their responses to various environmental stresses. To analysis the functional role of the RON1/SAL1 gene in response to oxidative stress induced by AT, several morphological, molecular and biochemical characterizations were assayed in Arabidopsis ron1-1 mutant plants, which has a point mutation in RON1/SAL1 and compared with those in wild type plants (Ler-0). The results showed a significant reduction in ron1-1 shoots, roots, and total plant weight in comparison with the wild type plants. Also, assessment of the chlorophyll content indicated a significant decrease in the mutant plants as compared with the wild types. In addition, a significant increase in ascorbate peroxidase enzyme activity in the mutant plants was detected. Also, catalase activity in mutant plants was increased in response to AT. Analysis of relative gene expression of oxidative marker genes including DEFL and sAPX in different concentrations of AT showed a significant increased in the expression of DEFL and sAPX genes in wild type plants compared to mutant plants. Therefore, probably the activity of RON1 protein caused by the ron1-1 mutation in mutant plants has been changed and this resulted in increased sensitivity to oxidative stress.

Various abiotic stresses lead to the overproduction of reactive oxygen species (ROS) in plants and cause to damage to proteins, lipids, carbohydrates and DNA. Antioxidative enzymes such as catalase and ascorbate peroxidase are activated to protect the plants against oxidative stress. Silicon is the second most common element in soil that has beneficial effects in improving plants tolerance to drought stress. Accordingly, the effects of drought stress on semi-quantitative gene expression and enzymatic activities of both catalase and ascorbate peroxidase were investigated in two lines of two-row barley named CB-20315 (resistant) and CB- 20213 (sensitive) in tillering stage in a greenhouse. The experiment was performed in a completely randomized design with three replications for three treatments of control, drought and silicon-drought (sodium silicate 2 mg / 1 kg), and analyzed in factorial experiment. RTPCR semi-quantitative analysis revealed significant differences between treatments. The highest level of gene expression was observed for both enzymes in the silicon-drought treatment. The data showed that silicone application affect antioxidant enzymes activity to increase in both studied lines under drought stress. According to the results of this study it might be concluded that silicon participate in physiological and metabolic changes to enhance plants tolerance to drought stress.

Cadmium is a heavy metal which accumulates in soil because of using chemical fertilizers & industrial stir. Heavy metals tension prevents 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. purpose of this study is determine the effect of cadmium on the activity of Superoxide dismutase, Polyphenol Oxydase, catalase and malondialdehyde also the content of Anthocyanin and chlorophyll a and b in were measured.The samples picked up in 30th day and used it for determination of biochemical parameters.the activity of SOD in aerobiosis bodies and CAT in aerobiosis bodies and in roots also Malondialdehyde has been significant increasing in shoot. The cadmium treatment have showed the meaningfull inclucreasing of PPO in 5cadmium and also the significant decreasing in 0.5 cadmium in aerobiosis bodies .Anthocyanin and a and b chlorophylls significant has decreased.

Polycyclic Aromatic Hydrocarbons (PAHs) are one of the tensions that inhibit plant growth and create imbalance between the production of Reactive Oxygen Species and antioxidant defense activities of the plant. Anthracene is the main pollutants in the petrochemical industry, which is located on the list of toxic pollutants, US Environmental Protection Agency (USEPA). In this study is to evaluate the effect of anthracene on some parameters of oxidative stress in Medicago sativa after 12 days of treatment with anthracene (2, 4 mmol per liter) in hydroponics, shoot and root tissues of the plants were harvested and used to measure biochemical parameters. The activity of superoxide dismutase(SOD), polyphenol oxidase(PPO), glutathione transferase(GST), peroxidase(PO), malondialdehyde and enzyme ascorbate peroxidase(APX) in shoot and root, as well as the activity of chlorophyll b and a the shoot was determined. The results showed that The high activities of SOD, APX, SPO, PPO and GST on the shoot of 4 mM anthracene is significant. Anthracene treatment, decreased MDA levels in shoot significantly. It is also associated with increased concentrations of chlorophyll a and b. Also increases the activity of the enzyme polyphenol oxidase is the result of the production of phenolic compounds in the plant.

Rice is an excellent model cereal for molecular biology and genetics research. Salinity is a major factor limiting rice production world wide. The analysis of stress-responsiveness in plants is an important route to the discovery of genes conferring stress tolerance and their use in breeding programs. To further understand the mechanism of plant response to salinity we employed a proteomic approach to profile the protein changes of rice 3th leaf and root under salt stress. Plants were grown in Yoshida nutrient solution and salt‏ stress imposed after 25 days. Plants were treated by 100¬‏mM NaCl for 10. After that 3th leaves and total root were collected from control and salt stressed plants. The Na+ and K+ content of leaves/roots and several yield components changed significantly in response to short-term salt stress and their proteome patterns were analyzed using 2-DE in triplicates. The expression pattern of proteins significantly changed in all leaves/roots in response to stress. More than 488 and 345 protein were detected repeatedly in root and leaf 2D‏gels respectively by software package. 107‏ proteins in root and 86 proteins in leaf of two genotypes showed significant response to stress. 3 protein in leaf gels and 2 protein in root gels were selected and identified by ESI-Q-TOF. The most important were Ferritin, Rubisco activase and ascorbat¬peroxidase in leaf and Peroxidase and Ascorbat¬peroxidase in root. All of them were enzyme and involved in detoxification and removal of reactive oxygen species (peroxidase, ascorbat¬peroxidase) Iron homeostasis (ferritin) or activation of other enzymes (rubisco¬activase).