Yazar "Turkan, Ismail" seçeneğine göre listele

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    Ferulic acid confers tolerance against excess boron by regulating ROS levels and inducing antioxidant system in wheat leaves (Triticum aestivum)
    (Pergamon-Elsevier Science Ltd, 2019) Yildiztugay, Evren; Ozfidan-Konakci, Ceyda; Karahan, Huseyin; Kucukoduk, Mustafa; Turkan, Ismail
    Ferulic acid (FA; 3-methoxy-4-hydroxycinnamic acid) is a candidate for improving plant tolerance to stress conditions through improving water solubility and antioxidant activity. To our knowledge, no study has thus far explored the potential for exogenous FA application to improve tolerance against excess boron (B) in plants. For this purpose, wheat seedlings grown in hydroponic culture were treated with FA (25 and 75 mu M) alone or in combination with B (4 and 8 mM). The results showed that B caused a decrease in water content (RWC), osmotic potential (Psi(Pi)) and proline content (Pro). FA application prevented decreases of these parameters. 8 mM B increased superoxide dismutase (SOD) activity. Superoxide anion radical (O-2(center dot-))and hydrogen peroxide (H2O2) increased during B exposure, while catalase (CAT), peroxidase (POX), ascorbate peroxidase (APX) and glutathione reductase (GR) activities did not. However, due to increased SOD activity, FA under stress successfully decreased O-2(center dot-) content. Additionally, exogenously applied FA under 4mM B stress increased the activities of CAT and POX. While excess B in wheat leaves did not induce activities of APX, GR, monodehydroascorbate reductase (MDHAR) or dehydroascorbate reductase (DHAR) or increase total ascorbate (tAsA) or dehydroascorbate (DHA) contents, FA with stress did. 25 mu M FA with B remarkably maintained regeneration of ascorbate and induced contents of tAsA and GSH (including the ascorbate glutathione cycle) and induced CAT activity. Taken together, stress-induced H2O2 content significantly decreased and the scavenging of OH. increased in wheat with FA application through the activation of antioxidant enzymes. Consequently, FA prevented lipid peroxidation (TBARS) caused by stress due to increased radical scavenging activity.
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    Flavonoid Naringenin Alleviates Short-Term Osmotic and Salinity Stresses Through Regulating Photosynthetic Machinery and Chloroplastic Antioxidant Metabolism inPhaseolus vulgaris
    (Frontiers Media Sa, 2020) Yildiztugay, Evren; Ozfidan-Konakci, Ceyda; Kucukoduk, Mustafa; Turkan, Ismail
    The current study was conducted to demonstrate the possible roles of exogenously applied flavonoid naringenin (Nar) on the efficiency of PSII photochemistry and the responses of chloroplastic antioxidant of salt and osmotic-stressedPhaseolus vulgaris(cv. Yunus90). For this aim, plants were grown in a hydroponic culture and were treated with Nar (0.1 mM and 0.4 mM) alone or in a combination with salt (100 mM NaCl) and/or osmotic (10% Polyethylene glycol, -0.54 MPa). Both caused a reduction in water content (RWC), osmotic potential (psi(pi)), chlorophyll fluorescence (F-v/F-m), and potential photochemical efficiency (F-v/F-o). Nar reversed the changes on these parameters. The phenomenological fluxes (TRo/CS and ETo/CS) altered by stress were induced by Nar and Nar led to a notable increase in the performance index (PIABS) and the capacity of light reaction [phi P-o/(1-phi P-o)]. Besides, Nar-applied plants exhibited higher specific fluxes values [ABS/RC, ETo/RC, and psi E-o/(1-psi E-o)] and decreasing controlled dissipation of energy (DIo/CS(o)and DIo/RC). The transcripts levels of psbA and psbD were lowered in stress-treated bean but upregulated in Nar-treated plants after stress exposure. Nar also alleviated the changes on gas exchange parameters [carbon assimilation rate (A), stomatal conductance (g(s)), intercellular CO(2)concentrations (C-i), transpiration rate (E), and stomatal limitation (L-s)]. By regulating the antioxidant metabolism of the isolated chloroplasts, Nar was able to control the toxic levels of hydrogen peroxide (H2O2) and TBARS (lipid peroxidation) produced by stresses. Chloroplastic superoxide dismutase (SOD) activity reduced by stresses was increased by Nar. In response to NaCl, Nar increased the activities of ascorbate peroxidase (APX), glutathione reductase (GR), monodehydroascorbate reductase (MDHAR), and dehydroascorbate reductase (DHAR), as well as peroxidase (POX). Nar protected the bean chloroplasts by minimizing disturbances caused by NaCl exposure via the ascorbate (AsA) and glutathione (GSH) redox-based systems. Under Nar plus PEG, Nar maintained the AsA regeneration by the induction of MDHAR and DHAR, but not GSH recycling by virtue of no induction in GR activity and the reduction in GSH/GSSG and GSH redox state. Based on these advances, Nar protected in bean chloroplasts by minimizing disturbances caused by NaCl or PEG exposure via the AsA or GSH redox-based systems and POX activity.
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    Halophytes as a source of salt tolerance genes and mechanisms: a case study for the Salt Lake area, Turkey
    (Csiro Publishing, 2016) Ozfidan-Konakci, Ceyda; Uzilday, Baris; Ozgur, Rengin; Yildiztugay, Evren; Sekmen, A. Hediye; Turkan, Ismail
    The worst case scenario of global climate change predicts both drought and salinity would be the first environmental factors restricting agriculture and natural ecosystems, causing decreased crop yields and plant growth that would directly affect human population in the next decades. Therefore, it is vital to understand the biology of plants that are already adapted to these extreme conditions. In this sense, extremophiles such as the halophytes offer valuable genetic information for understanding plant salinity tolerance and to improve the stress tolerance of crop plants. Turkey has ecological importance for its rich biodiversity with up to 3700 endemic plants. Salt Lake (Lake Tuz) in Central Anatolia, one of the largest hypersaline lakes in the world, is surrounded by salty marshes, with one of the most diverse floras in Turkey, where arid and semiarid areas have increased due to low rainfall and high evaporation during the summer season. Consequently, the Salt Lake region has a large number of halophytic, xerophytic and xero-halophytic plants. One good example is Eutrema parvulum (Schrenk) Al-Shehbaz & Warwick, which originates from the Salt Lake region, can tolerate up to 600mM NaCl. In recent years, the full genome of E. parvulum was published and it has been accepted as a model halophyte due to its close relationship (sequence identity in range of 90%) with Arabidopsis thaliana (L. Heynh.). In this context, this review will focus on tolerance mechanisms involving hormone signalling, accumulation of compatible solutes, ion transporters, antioxidant defence systems, reactive oxygen species (ROS) signalling mechanism of some lesser-known extremophiles growing in the Salt Lake region. In addition, current progress on studies conducted with E. parvulum will be evaluated to shed a light on future prospects for improved crop tolerance.
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    Hydrogen sulfide (H2S) and nitric oxide (NO) alleviate cobalt toxicity in wheat (Triticum aestivum L.) by modulating photosynthesis, chloroplastic redox and antioxidant capacity
    (Elsevier, 2020) Ozfidan-Konakci, Ceyda; Yildiztugay, Evren; Elbasan, Fevzi; Kucukoduk, Mustafa; Turkan, Ismail
    The role of hydrogen sulfide (H2S)/nitric oxide (NO) in mitigating stress-induced damages has gained interest in the past few years. However, the protective mechanism H2S and/or NO has towards the chloroplast system through the regulation of redox status and activation of antioxidant capacity in cobalt-treated wheat remain largely unanswered. Triticum aestivum L. cv. Ekiz was treated with alone/in combination of a H2S donor (sodium hydrosulfide (NaHS,600 mu M)), a NO donor (sodium nitroprusside (SNP,100 mu M)) and a NO scavenger (rutin hydrate (RTN,50 mu M)) to assess how the donors affect growth, water relations, redox and antioxidant capacity in chloroplasts, under cobalt (Co) concentrations of 150-300 mu M. Stress decreased a number of parameters (growth, water content (RWC), osmotic potential (psi(Pi)), carbon assimilation rate, stomatal conductance, intercellular CO2 concentrations, transpiration rate and the transcript levels of rubisco, which subsequently disrupt the photosynthetic capacity). However, SNP/NaHS counteracted the negative effects of stress on these aforementioned parameters and RTN application with stress/non-stress was reversed these effects. Hydrogen peroxide (H2O2) and TBARS were induced under stress in spite of activated ascorbate peroxidase (APX). SNP/NaHS under stress increased activation of superoxide dismutase (SOD), peroxidase (POX), APX, glutathione reductase (GR), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), ascorbate (tAsA) and glutathione (GSH). In conclusion, NaHS/SNP are involved in the regulation and modification of growth, water content, rubisco activity and up-regulation of ascorbate-glutathione cycle (AsA-GSH) in chloroplast under stress.
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    Influences of sulfonated graphene oxide on gas exchange performance, antioxidant systems and redox states of ascorbate and glutathione in nitrate and/or ammonium stressed-wheat (Triticum aestivum L.)
    (Royal Soc Chemistry, 2021) Ozfidan-Konakci, Ceyda; Yildiztugay, Evren; Cavusoglu, Halit; Arikan, Busra; Elbasan, Fevzi; Kucukoduk, Mustafa; Turkan, Ismail
    Graphene oxide has unique physiochemical properties and a large surface area. After functionalization, its shape, surface, adsorption capacity, and toxicity levels can change. The potential impacts of sulfonated graphene oxide (SGO, modified with the sulfonic group) on metabolic processes and biological pathways are unanswered questions concerning NO3- or NH4+ toxicity. To fill this gap of knowledge, in the present study, SGO (50-250-500 mg L-1) was applied to Triticum aestivum cv. Ekiz with/without 140 mM nitrate (NS stress) and 5 mM ammonium (AS stress). Both stress treatments suppressed the growth, water content, osmotic potential, and photosynthetic capacity, as detected by a decrease in the carbon assimilation rate (A), stomatal conductance (g(s)), intercellular CO2 concentration (C-i), and transpiration rate (E), and an increase in stomatal limitation. After stress exposure, SGO provided positive responses to these parameters. There were different responses in the antioxidant system under stress: superoxide dismutase (SOD) and peroxidase (POX) under NS stress; SOD, catalase (CAT) and POX under AS and NS + AS stresses. However, hydrogen peroxide (H2O2) and lipid peroxidation increased because lack of effective antioxidant activation. In response to NS or AS, SGO successfully regulated SOD, CAT, glutathione peroxidase (GPX) and the enzyme/non-enzymes related to the AsA-GSH cycle, attenuating the high levels of H2O2, lipoxygenase (LOX) and TBARS-based damage. Along with the antioxidant system, SGO controlled the contents of NO3- or NH4+ by regulation of NPF6.3 and AMT1.2 genes. Interestingly, under NS plus AS, the alleviation action of SGO varied in a concentration-dependent manner: (i) low SGO concentration (50 mg L-1) protected the regeneration of ascorbate (AsA) and glutathione (GSH) and the high activities of GST and GPX; (ii) 250 mg L-1 SGO maintained the GSH redox state and the induced activity of glutathione S-transferase (GST); (iii) the highest SGO concentration (500 mg L-1) did not eliminate H2O2 accumulation, which coincided with the increased levels of TBARS and LOX. The toxicity of the high SGO concentration was further increased in wheat with non-stress or NS plus AS stresses. Our findings specified that the damage stimulated by NS and/or AS stress was removed by SGO applications through the increased antioxidant activity and gas exchange parameters, resulting in the protection of the redox state.
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    Naringenin induces tolerance to salt/osmotic stress through the regulation of nitrogen metabolism, cellular redox and ROS scavenging capacity in bean plants
    (Elsevier France-Editions Scientifiques Medicales Elsevier, 2020) Ozfidan-Konakci, Ceyda; Yildiztugay, Evren; Alp, Fatma Nur; Kucukoduk, Mustafa; Turkan, Ismail
    The present study was conducted to uncover underlying possible effect mechanisms of flavonoid naringenin (Nar, 0.1-0.4 mM) in nitrogen assimilation, antioxidant response, redox status and the expression of NLP7 and DREB2A, on salt (100 mM NaCl) and osmotic-stressed (10% Polyethylene glycol, -0.54 MPa) Phaseolus vulgaris cv. Yunus 90). Nar ameliorated salt/osmotic stresses-induced growth inhibition and improved the accumulation of proline, glycine betaine and choline. In response to stress, Nar increased endogenous content of nitrate (NO3-) and nitrite (NO2-) by regulating of nitrate reductase and nitrite reductase. Stress-triggered NH4+ was eliminated with Nar through increases in glutamine synthetase and glutamate synthase. After NaCl or NaCl + PEG exposure, Nar utilized the aminating activity of glutamate dehydrogenase in the conversion of NH4+. The stress-inducible expression levels of DREB2A were increased further by Nar, which might have affected stress tolerance of bean. Nar induced effectively the relative expression of NLP7 in the presence of the combination or alone of stress. Also, the impaired redox state by stress was modulated by Nar and hydrogen peroxide (H2O2) and TBARS decreased. Nar regulated the different pathways for scavenging of H2O2 under NaCl and/or PEG treatments. When Nar + NaCl exposure, the damage was removed by superoxide dismutase (SOD), catalase (CAT), PDX (only at 0.1 mM Nar + NaCl) and AsA-GSH cycle. Under osmotic stress plus Nar, the protection was manifested by activated CAT and, glutathione 5-transferase and the regeneration of ascorbate. 0.1 mM Nar could protect bean plant against salt/osmotic stresses, likely by regulating nitrogen assimilation pathways, improving expression levels of genes associated with tolerance mechanisms and modulating the antioxidant capacity and AsA-GSH redox-based systems.