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    The effects of fullerene on photosynthetic apparatus, chloroplast-encoded gene expression, and nitrogen assimilation in Zea mays under cobalt stress
    (Wiley, 2022) Ozfidan-Konakci, Ceyda; Alp, Fatma Nur; Arikan, Busra; Balci, Melike; Parmaksizoglu, Zeynep; Yildiztugay, Evren; Cavusoglu, Halit
    Carbon nanostructures, such as the water-soluble fullerene (FLN) derivatives, are considered perspective agents for agriculture. FLN can be a novel nano-agent modulating plant response against stress conditions. However, the mechanism underlying the impacts of FLN on plants in agroecosystems remains unclear. Zea mays was exposed to exogenous C-60-FLN applications (FLN1: 100; FLN2: 250; and FLN3: 500 mg L-1) with/without cobalt stress (Co, 300 mu M) for 3 days (d). In the maize chloroplasts, Co stress disrupted the photosynthetic efficiency and the expression of genes related to the photosystems (psaA and psbA). FLNs effectively improved the efficiency and photochemical reaction of photosystems. Co stress induced the accumulation of reactive oxygen species (ROS) as confirmed by ROS-specific fluorescence in guard cells. Co stress increased only chloroplastic superoxide dismutase (SOD) and peroxidase (POX). Stress triggered oxidative damages in maize chloroplasts, measured as an increase in TBARS content. In Co-stressed seedlings exposed to FLN1 and FLN2 exposures, the hydrogen peroxide (H2O2) was scavenged through the nonenzymes/enzymes-related to the AsA-GSH cycle by preserving ascorbate (AsA) conversion, as well as GSH/GSSG and glutathione (GSH) redox state. Also, the alleviation effect of FLN3 against stress could be attributed to increased glutathione S-transferase (GST) activity and AsA regeneration. FLN applications reversed the inhibitory effects of Co stress on nitrogen assimilation. In maize chloroplasts, FLN increased the activities of nitrate reductase (NR), glutamate dehydrogenase (GDH), nitrite reductase (NiR), and glutamine synthetase (GS), which provided conversion of inorganic nitrogen (N) into organic N. The ammonium (NH4+) toxicity was removed via GS and GDH but not glutamate synthase (GOGAT). The increased NAD-GDH (deaminating) and NADH-GDH (aminating) activities indicated that GDH was needed more for NH4+ detoxification. Therefore, FLN exposure to Co-stressed maize plants might play a role in N metabolism regarding the partitioning of N assimilates. Exogenous FLN conceivably removed Co toxicity by improving the expressions of genes related to reaction center proteins of photosystems, increasing the level of enzymes related to the defense system, and improving the N assimilation in maize chloroplasts.
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    The exogenous application of naringenin and rosmarinic acid modulates functional traits in Lepidium sativum
    (Wiley, 2023) Salehi, Hajar; Zhang, Leilei; Alp-Turgut, Fatma Nur; Arikan, Busra; Elbasan, Fevzi; Ozfidan-Konakci, Ceyda; Balci, Melike
    BACKGROUND: Phenolic modulators have attracted attention for their potential in shaping functional traits in plants. This work investigated the impact of naringenin (Nar) and rosmarinic acid (RA) on the functional properties of Lepidium sativum leaves and roots.Results: Untargeted metabolomics identified a diverse phenolic profile, including flavonoids, phenolic acids, low molecular weight phenolics, lignans, and stilbenes. Cluster, analysis of variance multiblock orthogonal partial least squares (AMOPLS), and orthogonal projection to latent structures discriminant analysis (OPLS-DA) multivariate analyses confirmed tissue-specific modulation of bioactive compounds. The tissue was the hierarchically most influential factor, explaining 27% of observed variability, while the treatment and their interaction were statistically insignificant. Thereafter, various in vitro assays were employed to assess antioxidant capacity, including 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2 '-azino-bis(3-ethylbenzothiazoline)-6-sulfonic acid (ABTS) radical scavenging activity, cupric ion reducing antioxidant capacity (CUPRAC), and ferric ion reducing antioxidant power (FRAP), metal chelating ability, and phosphomolybdenum (PMD) assays. Extracts were also tested for inhibitory effects on cholinesterase, amylase, glucosidase, and tyrosinase enzymes. RA application positively impacted antioxidant and enzyme inhibitory activities, holding valuable implications in shaping the health-promoting properties of L. sativum.Conclusion: The untargeted metabolomics analysis showed a significant tissue-dependent modulation of bioactive compounds, determining no synergistic effect between applying phenolic compounds in combination. Specifically, the sole application of RA increased anthocyanins and hydroxyphenyl propanoic acid content on leaves, which was strictly related to enhancing the biological activities.(c) 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
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    Fe2O3-modified graphene oxide mitigates nanoplastic toxicity via regulating gas exchange, photosynthesis, and antioxidant system in Triticum aestivum
    (Pergamon-Elsevier Science Ltd, 2022) Arikan, Busra; Alp, Fatma Nur; Ozfidan-Konakci, Ceyda; Balci, Melike; Elbasan, Fevzi; Yildiztugay, Evren; Cavusoglu, Halit
    The ever-increasing plastic pollution in soil and water resources raises concerns about its effects on terrestrial plants and agroecosystems. Although there are many reports about the contamination with nanoplastics on plants, the presence of magneto-assisted nanomaterials enabling the removal of their adverse impacts still re-mains unclear. Therefore, the purpose of the current study is to evaluate the potential of nanomaterial Fe2O3- modified graphene oxide (FGO, 50-250 mg L-1) to eliminate the adverse effects of nanoplastics in plants. Wheat plants exposed to polystyrene nanoplastics concentrations (PS, 10, 50 and 100 mg L-1) showed decreased growth, water content and loss of photosynthetic efficiency. PS toxicity negatively altered gas exchange, antenna structure and electron transport in photosystems. Although the antioxidant system was partially activated (only superoxide dismutase (SOD), NADPH oxidase (NOX) and glutathione reductase (GR)) in plants treated with PS, it failed to prevent PS-triggered oxidative damage, as showing lipid peroxidation and hydrogen peroxide (H2O2) levels. FGOs eliminated the adverse impacts of PS pollution on growth, water status, gas exchange and oxidative stress markers. In addition, FGOs preserve the biochemical reactions of photosynthesis by actively increasing chlorophyll fluorescence parameters in the stressed-wheat leaves. The activities of all enzymatic antioxidants increased, and the H2O2 and TBARS contents decreased. GSH-mediated detoxifying antioxidants such as gluta-thione S-transferase (GST) and glutathione peroxidase (GPX) were stimulated by FGOs against PS pollution. FGOs also triggered the enzymes and non-enzymes related to the Asada-Halliwell cycle and protected the regeneration of ascorbate (AsA) and glutathione (GSH). Our findings indicated that FGO had the potential to mitigate nanoplastic-induced damage in wheat by regulating water relations, protecting photosynthesis reactions and providing efficient ROS scavenging with high antioxidant capacity. This is the first report on removing PS -induced damage by FGO applications in wheat leaves.
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    Halotolerant plant growth-promoting bacteria, Bacillus pumilus, modulates water status, chlorophyll fluorescence kinetics and antioxidant balance in salt and/or arsenic-exposed wheat
    (Academic Press Inc Elsevier Science, 2023) Ozfidan-Konakci, Ceyda; Arikan, Busra; Alp-Turgut, Fatma Nur; Balci, Melike; Uysal, Ahmet; Yildiztugay, Evren
    Seed priming is an effective and novel technique and the use of eco-friendly biological agents improves the physiological functioning in the vegetative stage of plants. This procedure ensures productivity and acquired stress resilience in plants against adverse conditions without contaminating the environment. Though the mechanisms of bio-priming-triggered alterations have been widely explained under induvial stress conditions, the interaction of combined stress conditions on the defense system and the functionality of photosynthetic apparatus in the vegetative stage after the inoculation to seeds has not been fully elucidated. After Bacillus pumilus inoculation to wheat seeds (Triticum aestivum), three-week-old plants were hydroponically exposed to the alone and combination of salt (100 mM NaCl) and 200 mu M sodium arsenate (Na2HAsO4 center dot 7H(2O), As) for 72 h. Salinity and As pollutant resulted in a decline in growth, water content, gas exchange parameters, fluorescence kinetics and performance of photosystem II (PSII). On the other hand, the seed inoculation against stress provided the alleviation of relative growth rate (RGR), relative water content (RWC) and chlorophyll fluorescence. Since there was no effective antioxidant capacity, As and/or salinity caused the induction of H2O(2) accumulation and thiobarbituric acid reactive substances content (TBARS) in wheat. The inoculated seedlings had a high activity of superoxide dismutase (SOD) under stress. B. pumilis decreased the NaCl-induced toxic H2O2 levels by increasing peroxidase (POX) and enzymes/non-enzymes related to ascorbate-glutathione (AsA-GSH) cycle. In the presence of As exposure, the inoculated plants exhibited an induction in CAT activity. On the other hand, for H2O2 scavenging, the improvement in the AsA-GSH cycle was observed in bacterium priming plants plus the combined stress treatment. Since B. pumilus inoculation reduced H2O2 levels against all stress treatments, lipid peroxidation subsequently decreased in wheat leaves. The findings obtained from our study explained that the seed inoculation with B. pumilus provided an activation in the defense system and protection in growth, water status, and gas exchange regulation in wheat plants against the combination of salt and As.
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    Multiwalled Carbon Nanotubes Alter the PSII Photochemistry, Photosystem-Related Gene Expressions, and Chloroplastic Antioxidant System in Zea mays under Copper Toxicity
    (Amer Chemical Soc, 2022) Alp, Fatma Nur; Arikan, Busra; Ozfidan-Konakci, Ceyda; Balci, Melike; Yildiztugay, Evren; Cavusoglu, Halit
    A critical approach against copper (Cu) toxicity is the use of carbon nanomaterials (CNMs). However, the effect of CNMs on Cu toxicity-exposed chloroplasts is not clear. The photosynthetic, genetic, and biochemical effects of multiwalled carbon nanotubes (50-100-250 mg L-1 CNT) were investigated under Cu stress (50-100 mu M CuSO4) in Zea mays chloroplasts. F-v/F-m and F-v/F-o were suppressed under stress. Stress altered the antioxidant system and the expression of psaA, psaB, psbA, and psbD. The chloroplastic activities of superoxide dismutase (SOD), ascorbate peroxidase (APX), glutathione S-transferase (GST), and glutathione peroxidase (GPX) increased under CNT + stress, and those of hydrogen peroxide (H2O2) and lipid peroxidation decreased. CNTs were promoted to the maintenance of the redox state by regulating enzyme/non-enzyme activity/contents involved in the AsA-GSH cycle. Furthermore, CNTs inverted the negative effects of Cu by upregulating the transcriptions of photosystem-related genes. However, the high CNT concentration had adverse effects on the antioxidant capacity. CNT has great potential to confer tolerance by reducing Cu-induced damage and protecting the biochemical reactions of photosynthesis.
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    Polyamine Cadaverine Detoxifies Nitrate Toxicity on the Chloroplasts of Triticum aestivum Through Improved Gas Exchange, Chlorophyll a Fluorescence and Antioxidant Capacity
    (Springer, 2023) Balci, Melike; Alp, Fatma Nur; Arikan, Busra; Ozfidan-Konakci, Ceyda; Yildiztugay, Evren
    Nitrate (NO3-) toxicity is a serious problem that threatens the health of living organisms and especially agricultural production. The presence of NO3- leads to biomass loss by causing the imbalance of biochemical metabolism and inhibiting photosynthetic activity. A new critical approach to cope with nitrate toxicity is the use of polyamines (PAs) as an antioxidant defence system enhancer in plants. However, there is no information about the impacts of cadaverine, is one of PAs, on chloroplasts of plants exposed to NO3- toxicity. For this purpose, this study focused on the photosynthetic and biochemical process taking place in chloroplasts of Triticum aestivum under nitrate stress (100 mM and 200 mM NO3-) and/or cadaverine (100 mu M and 1 mM Cad). Gas exchange, chlorophyll fluorescence (F-v/F-m and F-v/F-o), the efficiency of the light reaction (phi P-o/(1 - phi P-o)), the performance index (PItotal), and relative water content (RWC) levels were suppressed under NO3- stress. Stress did not improve the antioxidant activities in chloroplasts such as superoxide dismutase (SOD), glutathione reductase (GR). After 100 mM NO3- exposure, Cad increased chloroplastic SOD, peroxidase (POX), ascorbate peroxidase (APX), GR, monodehydroascorbate reductase (MDHAR), and glutathione S-transferase (GST) activities. In the presence of 200 mM NO3-, Cads decreased SOD and GST activity. In NO3- + Cad-applied wheat, the high contents of hydrogen peroxide (H2O2) and lipid peroxidation (TBARS) were effectively removed through ascorbate (AsA) regeneration. Cads promoted the maintenance of cellular redox state by regulating antioxidant pathways included in the ascorbate-glutathione (AsA-GSH) cycle. Our results showed that Cad has great potential to confer tolerance to wheat by reducing oxidative damage and protecting the biochemical reactions of photosynthesis against NO3- toxicity.