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Öğe Biochar triggers systemic tolerance against cobalt stress in wheat leaves through regulation of water status and antioxidant metabolism(SPRINGER INTERNATIONAL PUBLISHING AG, 2019) Yildiztugay, Aysegul.; Ozfidan-Konakci, Ceyda.; Yildiztugay, Evren.; Kucukoduk, Mustafa.To eliminate the damages of metal toxicity by reducing metal uptake by plants, organic amendments are useful. The use of carbon-rich materials known as biochar (BC) is a strong candidate to enhance the plant tolerance against stress conditions. The current study examined the effects of BC in wheat hydroponically grown treated with BC (1 and 3 g L-1) alone or in combination with cobalt (Co, 150 and 300 mu M). Stress reduced the relative growth rate (RGR), relative water content (RWC), osmotic potential (Psi(Pi)), and increased proline content (Pro). Besides, endogenous contents of Ca2+, K+, and Mn2+ in leaves decreased under stress. In response to Co stress, a decline in the activities of peroxidase (POX), ascorbate peroxidase (APX), and glutathione reductase (GR) resulted in the induction of hydrogen peroxide (H2O2) content. BC applied with stress decreased endogenous Co2+ content and increased RGR, RWC, chlorophyll fluorescence and Pro content. Also, the activities of superoxide dismutase (SOD), catalase (CAT), APX and GR were induced and the ascorbate (AsA) and glutathione (GSH) pool and their redox state were maintained by BC application under stress condition. While, with the addition of BC, H2O2 content and lipid peroxidation displayed remarkable decreased, the scavenging activity of hydroxyl radical (OH center dot) increased as compared to Co stress-treated wheat plants. Besides, in wheat leaves, BC application triggered AsA-GSH pathway including activities of monodehydroascorbate reductase, dehydroascorbate reductase, and the contents of dehydroascorbate, GSH, and GSH/GSSG ratio. The presented results supported the view that biochar under stress could minimize the Co-induced oxidative damages through modulation of the growth, water status, photosynthetic apparatus, and antioxidant enzyme activity found in cellular compartments and ascorbate-glutathione cycle in wheat leaves.Öğe Cold stress in soybean (Glycine max L.) roots: exogenous gallic acid promotes water status and increases antioxidant activities(UNIV BELGRADE, INST BOTANY & BOTANICAL GARDEN, 2019) Ozfidan-Konakci, Ceyda.; Yildiztugay, Evren.; Yildiztugay, Aysegul.; Kucukoduk, Mustafa.Gallic acid (GLA; 3,4,5-trihydroxybenzoic acid) is a strong antioxidant in plants. In order to clarify the effects of GLA as a pro-oxidant or an antioxidant on cells under stress conditions, soybean (Glycine max) was grown under normal conditions or in the presence of cold stress (5 and 10 degrees C) in the absence or presence of gallic acid (GLA; 1 and 2 mM) for 72 h. The soybean roots exposed to stress exhibited a significant decline in growth (RGR), water content (RWC), osmotic potential (psi(Pi)) and proline content (Pro). However, GLA treatment under stress significantly improved these parameters and alleviated the stress-generated damage. Stress decreased superoxide dismutase (SOD) activity, but GLA effectively mitigated the adverse effects on enzyme activity. After stress treatment, only catalase (CAT) was induced in soybean roots, although it was not sufficient to prevent toxic hydrogen peroxide (H2O2) accumulation. Thus, the levels of lipid peroxidation (TBARS content) markedly increased. However, GLA contributed to detoxification of H2O2 and lipid peroxidation by enhancing activities of CAT and peroxidase (POX). In addition to these enzymes, SOD activity was able to scavenge superoxide anion radicals, as evidenced by decline in TBARS content. However, monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), total ascorbate (tAsA) and glutathione (GSH) showed a decline of content in roots treated with GLA (both concentrations) plus stress. Our results suggest a protective role of GLA, which may strengthen plant tolerance by ensuring efficient water use and enhancing antioxidant systems. In soybean roots, GLA successfully alleviated the toxicity of cold stress by modulating the activities of SOD, CAT and POX rather than enzymes of the ascorbate-glutathione cycle.Öğe 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.Öğe Humic acid protects against oxidative damage induced by cadmium toxicity in wheat (Triticum aestivum) roots through water management and the antioxidant defence system(UNIV BELGRADE, INST BOTANY & BOTANICAL GARDEN, 2019) Yildiztugay, Evren.; Ozfidan Konakci, Ceyda.; Elbasan, Fevzi.; Yildiztugay, Aysegul.; Kucukoduk, Mustafa.Humic compounds like humic acid (HA) promote ecosystem health by stabilising soil structure and promoting plant development. However, the amount needed is a limiting factor. The use of biostimulants based on HA is an effective way to eliminate oxidative damage caused by heavy metals such as cadmium (Cd) in plants. The aim of this study was to assess the effects of humic acid (HA; 750 and 1500 mg L-1) on growth, the osmotic potential, the antioxidant system, radical content and lipid peroxidation in wheat (Triticum aestivum) roots treated alone or in combination with Cd stress (100 and 200 mu M). Cadmium-treated wheat roots showed a reduction in growth (RGR) and the osmotic potential (Psi(Pi)) and an increase in proline content (Pro). Although 100-mu M Cd stress induced the activities of catalase (CAT) and ascorbate peroxidase (APX), hydrogen peroxide (H2O2) accumulation in roots exposed to stress was not prevented. The membrane of roots showed stress-dependent lipid peroxidation (TBARS content). Application of HA in combination with stress alleviated RGR and Psi(Pi) by promoting water intake. Humic acid reduced levels of H2O2 and TBARS through activation of superoxide dismutase (SOD) and CAT. Application of HA under stress also induced enzymes and non-enzymatic substances included in the ascorbate-glutathione cycle such as APX, monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR) and glutathione (GSH), in addition to which it increased GSH/GSSG ratios. These results indicate that HA alleviated the negative effects of Cd-induced oxidative damage in wheat roots through regulation of growth, osmotic adjustment, radical accumulation and the action of antioxidant systems.
