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  • 1
    Language: English
    In: Plant Science, December 2018, Vol.277, pp.139-144
    Description: One of the main sites of the magnetic fields influence on living cells is the cell cycle. The intensity of this influence however, varies depending on the cell type and the duration of the treatment. Suspension of cultured tobacco cells ( cv. Barley 21) were synchronized via sucrose starvation at their stationary growth phase. The cells were then exposed to 0.2 m T SMF up to 24 h. The progression of different cell cycle phases was monitored through flow cytometry in a time course manner. Expression of cell cycle controlling genes and amounts of certain signaling molecules were measured as well. Exposure to SMF delayed G1.S transition which was accompanied by decrease of cyclin-dependent kinases A (CDK A) and D-type cyclin, but an increase in the adenylyl cyclase (AC), transcription factor E2F, retinoblastoma protein (Rbp), and CDK-inhibitor protein 21 (p21) transcript accumulation. Exposure to SMF also increased the contents of nitric oxide (NO), hydrogen peroxide (H O ), and salicylic acid (SA), compared to the control group. The results suggest a signaling pathway triggered by SMF starting from accumulation of NO and H O followed by downstream events including the increase of cyclic nucleotides and subsequent decrease of both CDKA and CycD.
    Keywords: Cell Cycle Progression ; Magnetic Field ; Nicotiana Tabacum ; Nitric Oxide ; Salicylic Acid ; Botany
    ISSN: 0168-9452
    E-ISSN: 1873-2259
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  • 2
    Language: English
    In: Environmental and Experimental Botany, September 2017, Vol.141, pp.41-49
    Description: The mechanisms through which nitric oxide (NO) can influence plant tolerance to Pb are unknown, but may be based on the accumulation of secondary metabolites such as phenolic compounds and polyamines (PAs). This hypothesis was tested by exposing hydroponically-cultured to Pb alone and in combination with sodium nitroprusside (SNP; NO donor), L-NAME (NO synthase inhibitor) and tungstate (TUN; nitrate reductase inhibitor) for a time course of 72 h. The inhibitors strongly repressed NO generation, verifying that Pb and Pb + SNP-induced NO is probably mediated by nitrite and arginine-dependent pathways. The results show that the Pb-induced inhibition of growth was alleviated through application of NO donor, which decreased Pb accumulation in the plant samples, but deteriorated with the decrease in NO, which indicates a higher level of Pb absorbed. The elevated contents of phenolic acids under Pb and Pb + SNP treatments was reduced by the NOS and NR inhibitors and was significantly associated with phenylalanine ammonia-lyase ( ) gene expression patterns. The arginine decarboxylase ( ) gene in the PAs biosynthesis pathway remained unchanged. Considerable alteration was observed in the conjugated PAs in response to the Pb and Pb + SNP applications when compared with the NR and NOS inhibitors that exhibited an increase in free PAs. The results suggest that Pb-evoked NO promotes homeostasis of metabolic pathways to phenolic acids and conjugated PAs that enhance lignification to strengthen against stress.
    Keywords: Nitric Oxide ; Phenolic Compounds ; Polyamines ; No Synthase ; Nitrate Reductase ; Prosopis Farcta ; Environmental Sciences ; Botany
    ISSN: 0098-8472
    E-ISSN: 1873-7307
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  • 3
    Language: English
    In: Ecotoxicology and Environmental Safety, August 2017, Vol.142, pp.293-302
    Description: Reactive oxygen species (ROS) and nitric oxide (NO) are known in triggering defense functions to detoxify heavy metal stresses. To investigate the relevance of ROS production, Pb treatment (400 µM) alone and in combination with 400 µM sodium ascorbate (Asc: as H O scavenger) were given to hydroponically grown seedlings over a time course of 72 h. Data presented here indicate that, the low extent of H O due to scavenging by ascorbate, together with high level of NO improved Pb+Asc- treated growth. Following the evoked potential of both the signals, significant increases in phenolic acids; caffeic, ferulic and salicylic acid were observed with Pb treatment; which are consistent with observed increase in lignin content and consequently with growth inhibition. In contrast, Pb+Asc treatment induced more flavonoids (quercetin, kaempferol, luteolin), diminished phenolic acids contents and also lignin. Elicited expression rate of phenylalanine ammonia-lyase gene ( ) and also its enzymatic activity verified the induced phenylpropanoid metabolism by Pb and Pb+Asc treatments. In comparison with Pb stress, Asc+Pb application induced the high expression of arginine decarboxylase gene ( ), in polyamines biosynthesis pathway, and conducted the N flow towards polyamines and γ-amino butyric acid (GABA). Examining the impact on enzyme activities, catalase, and guaiacol peroxidase; Pb+Asc reduced activity but this increased ascorbate peroxidase, and aconitase activity. Our observations are consistent with conditions favouring NO production and reduced H O can improve Pb tolerance via wide-ranging effects on a primary metabolic network.
    Keywords: Nitric Oxide ; Hydrogen Peroxide ; Phenylpropanoid Metabolism ; Polyamine ; Prosopis Farcta ; Ecology ; Public Health
    ISSN: 0147-6513
    E-ISSN: 1090-2414
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  • 4
    Language: English
    In: Plant Physiology and Biochemistry, September 2018, Vol.130, pp.139-147
    Description: Plants respond to water stress through a variety of mechanisms, depending on metabolites preferences and their available resources. This work was performed to elucidate the cross-talk between signaling molecules (polyamines (PAs), hydrogen peroxide (H O ) and nitric oxide (NO)), phenolic compounds and osmolytes (phenylethanoid glycosides (PhGs), phenolic acids, flavonoids, soluble sugars and amino acids) under water stress in plants. The results revealed that PAs, NO levels were enhanced in the plants, earlier in response to polyethylene glycol-induced water stress. The antioxidative mechanisms with increased activity of catalase (CAT), guaiacol peroxidase (GPX) and superoxide dismutase (SOD) and also phenylalanine ammonia-lyase (PAL), tyrosine ammonia-lyase (TAL), as key enzymes in phenolic pathway were deployed in response to the stress. Mannose, glucose, xylose/rhamnose which are involved in PhGs biosynthesis as well as in serving osmotic adjustment were modulated. The elevated content of arginine and methionine as PAs precursors and tyrosine and phenylalanine as PhGs precursors was enhanced by water stress and was significantly associated with PAs and PhGs accumulations. Metabolic profiling revealed new information about relationship between stress signal molecules; PAs, NO and H O , osmolytes (sugers, PhGs) and phenolic compounds which involved in the improvement of water stress tolerance in .
    Keywords: Phenylethanoid Glycosides ; Polyamines ; Nitric Oxide ; Water Stress ; Scrophularia Striata ; Botany ; Chemistry
    ISSN: 0981-9428
    E-ISSN: 1873-2690
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  • 5
    Language: English
    In: Plant Physiology and Biochemistry, February 2016, Vol.99, pp.11-20
    Description: Lead (Pb) is a hazardous heavy metal present in the environment which elicits oxidative stress in plants. To characterize the physiological and biochemical basis of Pb tolerance, seedlings were exposed to Hoagland's solutions at six different Pb concentrations (0, 80, 160, 320, 400 and 480 μM) for different periods of time. As expected, application of Pb significantly increased hydrogen peroxide (H O ) content. In response, deployed the antioxidative defence mechanisms with significantly higher activities of superoxide dismutase (SOD), enzymes related to H O removal, and also the increases in proline as a solute marker of stress. Increases were observed in nitric oxide (NO) production which could also act in triggering defense functions to detoxify Pb. Enhanced phenylalanine ammonia-lyase (PAL) activity at early days of exposure to Pb was correlated with increases in phenolic compounds. Significant increases in phenolic acids and flavonoids; daidzein, vitexin, ferulic acid and salicylic acid were observed with Pb treatment. Furthermore, the stress effects were followed by changes in free amino acid content and composition. Aspartic acid and glycine content was increased but glutamic acid significantly decreased. It is likely that stress signal transduction by NO and H O mediated defence responses to Pb by coordination of antioxidative system and metabolic pathways of phenylpropanoid and amino acids.
    Keywords: Lead ; Enzymatic Antioxidant ; Nitric Oxide ; Phenylalanine Ammonia-Lyase ; Phenolic Acids ; Amino Acids ; Botany ; Chemistry
    ISSN: 0981-9428
    E-ISSN: 1873-2690
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  • 6
    Language: English
    In: Plant Physiology and Biochemistry, February 2019, Vol.135, pp.359-371
    Description: Hydrogen sulfide (H S) has been recently found as an important signaling molecule especially in root system architecture of plants. The regulation of root formation through H S has been reported in previous works; while the profiling of metabolites in response to H S is not clearly discussed. To this end, different concentrations of sodium hydrosulfide (an H S donor) were applied to the culture of hairy roots. Subsequently, the amino acid profiles, soluble carbohydrates, and central intermediates of phenylpropanoid pathway with two branches of lignans and flavonoids were assessed by spectroscopy and high performance liquid chromatography techniques. An analysis of the signaling molecules (nitric oxide, hydrogen peroxide, and salicylic acid) was also conducted as they proposed to act in conjunction with H S. The H S activated antioxidant systems and caused a shift from flavonoid to lignan production (podophyllotoxin and 6-methoxypodophyllotoxin); although, some of the flavonoids increased in a dose-dependent manner. The H S decreased the contents of phenylalanine and tyrosine as substrates of the phenylpropanoid pathway, but increased proline and histidine as an osmolyte and antioxidant, respectively. These findings propose that H S modulates other signaling molecules, regulates free amino acids, and mediates biosynthesis of lignans and flavonoids in the phenylpropanoids biosynthesis pathway.
    Keywords: Hairy Root ; Hydrogen Sulfide ; Linum Album ; Phenylpropanoid ; Signaling ; Botany ; Chemistry
    ISSN: 0981-9428
    E-ISSN: 1873-2690
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