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    Amino-functionalized SiO2 microbeads optimize photosynthetic performance, gene expression, ROS production and antioxidant status in chromium and copper-exposed Zea mays
    (Elsevier Sci Ltd, 2023) Alp-Turgut, Fatma Nur; Yildiztugay, Evren; Ozfidan-Konakci, Ceyda; Sargin, Idris
    The objective of the current study was to assess the potential of the amino-functionalized SiO2 microbeads (S) in improving the tolerance of maize to chromium and/or copper toxicity. For this purpose, Zea mays L. cv. DKC5685 was grown by exposure at different S concentrations (100-500 mg L-1) alone and with 200 mu M chromium (Cr stress) and 100 mu M copper (Cu stress) for 7 days. The photosynthesis-related parameters (Fv/Fm, Fv/Fo), relative growth rate (RGR), and relative water content (RWC) levels were suppressed under Cr and/or Cu stresses. In addition, stress altered antioxidant activities and gas exchange parameters. S applications abolished the negative impacts of stress on the physiological state of the photosynthetic system, potential photochemical efficiency and chlorophyll fluorescence. S increased the performance index by reversing the detrimental effects on the electron flow rate through the PSII electron transport flux and electron transfer from the decreased plastoquinone pool to the PSI reaction center. Following exposure to S, the effects of stress on photosystem I-associated reaction center proteins were rearranged by induced expression levels of PsaA and PsaB genes. S treatments had potent ROS scavengers in maize leaves. In the Cr+S groups, the AsA-GSH cycle was regulated by increasing the activities of all the responsible enzymes mentioned above, such as SOD, CAT, APX and GR, and the accumulation of H2O2 and TBARS effectively removed. CAT and POX activities in Cu+S groups were not effective in these adjustments. In Cr+Cu+S applications, although H2O2 and TBARS contents were reduced as evidenced by ROS visualization using fluorescence of dye, AsA regeneration could not be achieved, and low tAsA/DHA levels were detected. Our results show that amino-functionalized SiO2 microbeads have significant promise to offer resistance to maize by minimizing oxidative damage brought on by heavy metal uptake and preserving the metabolic processes involved in photosynthesis.
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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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    Glutamate, Humic Acids and Their Combination Modulate the Phenolic Profile, Antioxidant Traits, and Enzyme-Inhibition Properties in Lettuce
    (Mdpi, 2023) De Gregorio, Marco Armando; Zengin, Gokhan; Alp-Turgut, Fatma Nur; Elbasan, Fevzi; Ozfidan-Konakci, Ceyda; Arikan, Busra; Yildiztugay, Evren
    Lettuce (Lactuca sativa L., Asteraceae) is a popular vegetable leafy crop playing a relevant role in human nutrition. Nowadays, novel strategies are required to sustainably support plant growth and elicit the biosynthesis of bioactive molecules with functional roles in crops including lettuce. In this work, the polyphenolic profile of lettuce treated with glutamic acid (GA), humic acid (HA), and their combination (GA + HA) was investigated using an untargeted metabolomics phenolic profiling approach based on high-resolution mass spectrometry. Both aerial and root organ parts were considered, and a broad and diverse phenolic profile could be highlighted. The phenolic profile included flavonoids (anthocyanins, flavones, flavanols, and flavonols), phenolic acids (both hydroxycinnamics and hydroxybenzoics), low molecular weight phenolics (tyrosol equivalents), lignans and stilbenes. Overall, GA and HA treatments significantly modulated the biosynthesis of flavanols, lignans, low molecular weight phenolics, phenolic acids, and stilbene. Thereafter, antioxidant capacity was evaluated in vitro with 2,2-diphenyln-1-picrylhydrazyl (DPPH), 2,2'-Azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), ferric reducing antioxidant power (FRAP), and cupric ion reducing antioxidant capacity (CUPRAC) assays. In addition, this study examined the inhibitory properties of enzymes, including acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), tyrosinase, alpha-amylase, and alpha-glucosidase. Compared to individual treatments, the combination of GA + HA showed stronger antioxidant abilities in free radical scavenging and reducing power assays in root samples. Moreover, this combination positively influenced the inhibitory effects of root samples on AChE and BChE and the tyrosinase inhibitory effect of leaf samples. Concerning Pearson's correlations, antioxidant and enzyme inhibition activities were related to phenolic compounds, and lignans in particular correlated with radical scavenging activities. Overall, the tested elicitors could offer promising insights for enhancing the functional properties of lettuce in agricultural treatments.
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    Graphene oxide-based aerogel stimulates growth, mercury accumulation, photosynthesis-related gene expression, antioxidant efficiency and redox status in wheat under mercury exposure
    (Elsevier Sci Ltd, 2024) Alp-Turgut, Fatma Nur; Ozfidan-Konakci, Ceyda; Arikan, Busra; Comak, Gurbuz; Yildiztugay, Evren
    Mercury (Hg) pollution is a global concern in cropland systems. Hg contamination causes a disruption in the growth, energy metabolism, redox balance, and photosynthetic activity of plants. In the removal of Hg toxicity, a recent critical strategy is the use of aerogels with biodegradability and biocompatibility. However, it is unknown how graphene oxide-based aerogels stimulate the defense systems in wheat plants exposed to Hg toxicity. Therefore, in this study, the photosynthetic, genetic, and biochemical effects of reduced graphene oxide aerogel treatments (gA; 50-100-250 mg L-1) were examined in wheat (Triticum aestivum) under Hg stress (50 mu M HgCl2). The relative growth rate (RGR) significantly decreased (84%) in response to Hg stress. However, the reduced RGR and water relations (RWC) of wheat were improved by gA treatments. The impaired gas exchange levels (stomatal conductance, carbon assimilation rate, intercellular CO2 concentrations, and transpiration rate) caused by stress were reversed under Hg plus gAs. Additionally, stress hampered chlorophyll fluorescence (F-v/F-o, F-v/F-m), and under Hg toxicity the expression of psaA genes was reduced (>0.4-fold), but psaB gene was significantly up-regulated (>3-fold) which are the genes involved in PSI. By increasing expression patterns of both genes relating to PSI, gAs reversed the adverse consequences on F-v/F-o and F-v/F-m in the presence of excessive Hg concentration. The activities of glutathione S-transferase (GST), glutathione reductase (GR), catalase (CAT), ascorbate peroxidase (APX) and dehydroascorbate reductase (DHAR) decreased under Hg toxicity. On the other hand, the activities of superoxide dismutase (SOD), APX, GST, and glutathione peroxidase (GPX) increased following gA treatments against stress, leading to the successful elimination of toxic levels of H2O2 and lipid peroxidation (TBARS content) by decreasing the levels by about 30%, and 40%, respectively. By modulating enzyme/non-enzyme activity/contents including the AsA-GSH cycle, gAs contributed to the protection of the cellular redox state. Most important of all, gA applications were able to reduce Hg intake by approximately 66%. Therefore, these results showed that gAs were effective in highly inhibiting Hg uptake and could significantly increase wheat tolerance to toxicity by eliminating Hg-induced oxidative damage and inhibiting metabolic processes involved in photosynthesis. The findings obtained from the study provide a new perspective on the alleviation roles of reduced graphene oxide aerogels as an effective adsorbent for decreasing damages of mercury toxicity in wheat plants.
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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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    Polyamine, 1,3-diaminopropane, regulates defence responses on growth, gas exchange, PSII photochemistry and antioxidant system in wheat under arsenic toxicity
    (Elsevier France-Editions Scientifiques Medicales Elsevier, 2023) Gulenturk, Cagri; Alp-Turgut, Fatma Nur; Arikan, Busra; Tofan, Aysenur; Ozfidan-Konakci, Ceyda; Yildiztugay, Evren
    The metalloid arsenic (As) is extremely hazardous to all living organisms, including plants. Pollution with As is very detrimental to the photosynthetic machinery, cell division, energy generation, and redox status. In order to cope with stress, the use of growth regulators such as polyamines (PA), which strengthen the antioxidant system of plants, has become widespread in recent years. PAs can modulate the plant growth through basic mechanisms common to all living organisms, such as membrane stabilization, free radical scavenging, deoxyribonucleic acid (DNA), ribonucleic acid (RNA) and protein synthesis, enzyme activities and second messengers. However, the effect of 1,3-diaminopropane (Dap), which is a product of PA catabolism, is not clear enough in plants exposed to As toxicity. In the current study, the different concentrations of 1,3-diaminopropane (0.1, 0.5 and 1 mM Dap) were hydroponically treated to wheat (Triticum aestivum) under arsenic stress (100 & mu;M As) and then relative growth rate (RGR), relative water content (RWC), proline content (Pro), gas exchange parameters, PSII photo-chemistry, chlorophyll fluorescence kinetics, antioxidant activity and lipid peroxidation were assessed. RGR, RWC, osmotic potential and Pro content decreased in As-applied plants. The inhibition of these parameters could be reversed by Dap treatments. Besides, Dap applications mitigated the As toxicity-induced suppression on chlorophyll fluorescence (Fv/Fm, Fv/Fo and Fo/Fm) and the performance of PSII photochemistry. As impaired the balance on antioxidant capacity by decreased activities of catalase (CAT), peroxidase (POX), glutathione peroxidase (GPX), ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), and the contents of ascorbate (AsA) and glutathione (GSH) and then lipid peroxidation (TBARS content) increased. In the presence of Dap under As stress, the plants exhibited an increase in superoxide dismutase (SOD), POX, and GPX. Dap treatments contributed to the maintenance of cellular redox state (AsA/ DHA and GSH/GSSG) by regulating the activities/contents of enzyme/non-enzyme involved in the AsA-GSH cycle. After Dap applications against stress, ROS accumulation (H2O2 content) and lipid peroxidation (TBARS) were effectively reduced. The findings showed that by eliminating As-induced oxidative damage and protecting the biochemical processes of photosynthesis, Dap treatments have a substantial potential to give resistance to wheat.
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    Polyvinylpyrrolidone-coated copper nanoparticles dose-dependently conferred tolerance to wheat under salinity and/or drought stress by improving photochemical activity and antioxidant system
    (Academic Press Inc Elsevier Science, 2024) Ekim, Rumeysa; Arikan, Busra; Alp-Turgut, Fatma Nur; Koyukan, Buket; Ozfidan-Konakci, Ceyda; Yildiztugay, Evren
    Copper (Cu) is one of the essential micronutrients for plants and has been used extensively in agricultural ap-plications from the past to the present. However, excess copper causes toxic effects such as inhibiting photo-synthesis, and disrupting biochemical processes in plants. Nanotechnology applications have offered a critical method for minimizing adverse effects and improving the effectiveness of copper nanoparticles. For this purpose, this study investigated the physiological and biochemical effects of polyvinylpyrrolidone (PVP)-coated Cu nanoparticles (PVP-Cu NP, N1, 100 mg L-1; N2, 400 mg L-1) in Triticum aestivum under alone or combined with salt (S, 150 mM NaCl) and/or drought (D, %10 PEG-6000) stress. Salinity and water deprivation caused 51% and 22% growth retardation in wheat seedlings. The combined stress condition (S + D) resulted in an approximately 3-fold reduction in the osmotic potential of the leaves. PVP-Cu NP treatments to plants under stress, especially N1 dose, were effective in restoring growth rate and regulating water relations. All stress treatments limited gas exchange in stomata and suppressed the maximal quantum yield of PSII (Fv/Fm). More than 50% improvement was observed in stomatal permeability and carbon assimilation rate under S + N1 and S + N2 applications. Examination of OJIP transient parameters revealed that N1 treatments protected photochemical reactions by reducing the dissipated energy flux (DIo/RC) in drought and S + D conditions. Exposure to S and/or D stress caused high hydrogen peroxide (H2O2) accumulation and lipid peroxidation in wheat leaves. The results indi-cated that S + N1 and S + N2 treatments reduced oxidative damage by stimulating the activities of antioxidant enzymes superoxide dismutase (SOD), peroxidase (POX), and ascorbate peroxidase (APX). Although similar ef-fects were observed at D and S + D conditions with 100 mg L-1 PVP-Cu NP treatments (N1), the curative effect of the N2 dose was not observed. In D + N1 and S + D + N1 groups, AsA regeneration and GSH redox status were maintained by triggering APX, GR, and other enzyme activities belonging to the AsA-GSH cycle. In these groups, N2 treatment did not contribute to the availability of enzymatic and non-enzymatic antioxidants. As a result, this study revealed that N1 dose PVP-Cu NP application was successful in providing stress tolerance and limiting copper-induced adverse effects under all stress conditions.
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    The regulatory effects of biochar on PSII photochemistry, antioxidant system and nitrogen assimilation in Lemna minor exposed to inorganic pollutants, arsenic and fluoride
    (Elsevier Sci Ltd, 2023) Yildiztugay, Evren; Ozfidan-konakci, Ceyda; Arikan, Busra; Alp-Turgut, Fatma Nur; Guenturk, Cagri
    The excessive accumulation of inorganic pollutants such as arsenic (As) and fluoride (F) are destructive contaminants for plants. There are some reports about the toxicity mechanisms of individual exposure of As or F. Biochar (BC), carbon-rich organic material, can sequester pollutants and help in increasing growth, nutrient uptake and water holding capacity in soils. However, the defense responses of plants to a combination of two stresses and the interactions between BC and combined exposure of As and F are not explicit. In order to fill this gap, different BC concentrations (BC1; 1 g L- 1 and BC2; 5 g L- 1) were hydroponically applied to Lemna minor subjected to sodium fluoride (F, 15 mM NaF) and sodium arsenate (As, 100 & mu;M Na2HAsO4). As or F pollutants caused a reduction in the chlorophyll fluorescence (Fv/Fm and Fv/Fo) but BC application under stress conditions improved the fluorescence levels. The photochemical reactions of photosystems and fluorescence kinetics impaired by stress were re-regulated through all BC concentrations. The relative expressions of genes belonging to proteins in PSI-PSII (psaA, psaB, psbA and psbD) were up-regulated in both BCs and As/F treatments. As-treated L. minor had only induction in superoxide dismutase-SOD- and ascorbate peroxidase-APX-, the enhancement in SOD, catalase-CAT-, glutathione reductase-GR- and glutathione S-transferase-GST- was observed under F toxicity. Also, the joint stress (As+F) caused declines in all antioxidant capacities except with SOD activity. Due to the sufficient antioxidant activation, hydrogen peroxide (H2O2) and thiobarbituric acid reactive substances (TBARS) increased in L. minor. While, 1 mg L-1 BC induced the regeneration of ascorbate (AsA) under individual application of As or F, 5 mg L-1 BC increased APX, MDHAR, DHAR, total ascorbate (tAsA), and DHA against F stress. As- and NaF-mediated stress suppressed the nitrogen assimilation of L. minor. Interestingly, the induced accumulation of NH4+ was prevented in BC plus stress-applied plants through glutamate dehydrogenase (GDH) activity rather than glutamine synthetase-glutamate synthase (GS-GOGAT) pathways. All findings indicated that BCs reduced lipid peroxidation and ROS accumulation by modulating electron fluxes and photochemistry in PSI and PSII, gene expression, nitrogen metabolism as well as the antioxidant system under stress conditions (As, F, and As+F).