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    COMPARATIVE ANALYSIS OF BIOCHEMICAL CONTENT, ANTIMICROBIAL AND ANTIOXIDANT ACTIVITIES OF HYPERICUM PERFORATUM L. SPECIES IS GROWN IN T?RK?YE
    (Pakistan Botanical Soc, 2023) Gul, Volkan; Cetinkaya, Hatice; Dinler, Burcu Seckin; Sefaoglu, Firat
    Many external factors, such as climatic conditions, geographical differences, and altitude, directly affect the primary and secondary metabolites and therapeutic use of St. John's Wort (Hypericum perforatum L.), an important plant in alternative medicine. This study was carried out to identify the antioxidant and antimicrobial activities and the content of proline, malondialdehyde, hydrogen peroxide, flavonoid, anthocyanin, and total phenolic in the St. John's Wort growing naturally in different regions of Bayburt. The St. John's Wort samples were collected from 11 different locations. As a result of the analyses carried out on the plant samples, it was found that the content of proline was within the range of 4.6-8.2 mu mol g-1 DW, the amount of malondialdehyde was within the range of 0.69-1.10 nmol g-1 DW, the amount of hydrogen peroxide was within the range of 79.89-155.49 mu mol g-1 DW, the amount of flavonoids was within the range of 91.38%100.27%, the amount of anthocyanin was within the range of 0.15-1.11 mkmol g-1 DW, the total phenolic content was within the range of 15.82-45.22 mg GAE g-1, and the antioxidant activity was within the range of 6.07-105.60 mu g mL-1.In conclusion, although the biochemical contents and nonenzymatic antioxidant activities showed a wide variety, the antioxidant activity was found to be higher in samples 5, 8, and 11. According to the antimicrobial activity results, some plant extracts were effective on bacteria and fungi, especially samples 5, 6, 8, and 11 showed an effect at the concentration of 200 mu g mL-1. This study, the first regional study on this subject, will contribute to future research and clinical trials in the health field.
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    Effects of titanium dioxide nanoparticles against salt and heat stress in safflower cultivars
    (Soc Botanica Brasil, 2024) Dinler, Burcu Seckin; Cetinkaya, Hatice; Koc, Fatma Nur; Gul, Volkan; Sefaoglu, Firat
    This study aimed to determine the effects of titanium dioxide nanoparticle (TiO2NP) pretreatment on seeds of different safflower cultivars (Balci, Dincer) under salt and heat stresses. The apparent effects on stress markers (malondialdehyde (MDA), hydrogen peroxide (H2O2) and superoxide radical (O2 center dot-) content), as well as changes in germination and physiological parameters (radicle and plumula weight and length measurements), were investigated. TiO2NP pretreatment caused an increase in radicle length and plumula fresh weight for the Balci cultivar under salinity. Furthermore, plumula dry weight was alleviated with TiO2NP pretreatment for both cultivars. TiO2NP pretreatment improved plumula dry and fresh weights for both cultivars under heat stress. In addition, MDA content decreased for both cultivars under heat stress but only for Balci under salt stress. The amount of O2 center dot- radicals positively affected only the radicle for both cultivars under heat stress. This study is the first to document the alleviation of salt stress damage for the Balci safflower cultivar, and protection for both Balci and Dincer cultivars under heat stress, using 200 ppm TiO2NP pretreatment.
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    Investigation of Comparative Regulation on Antioxidant Enzyme System under Copper Treatment and Drought Stress in Maize (Zea mays L.)
    (Univ Agr Sci & Veterinary Med Cluj-Napoca, 2014) Cetinkaya, Hatice; Seckin Dinler, Burcu; Tasci, Eda
    The present study was conducted to present the responses of drought-sensitive 'Shemal' and drought-tolerant '71MAY69' maize cultivars under drought condition (20% Polyethylene glycol, -0.40 MPa) and three different copper concentrations (0.5 mM, 1 mM, 1.5 mM CuSO4 center dot 5H(2)O) for 5 days to determine the enzymatic responses of copper treatment in maize leaves. Copper treatments alone did not change stomata! conductance, relative water content, malondialdehyde, proline, hydrogen peroxide content and abscisic acid level according to control groups. Combined treatment (drought and copper) alleviated the damage of PEG- induced drought stress in maize leaves. Superoxide dismutase (SOD), catalase (CAT), glutatione reductase (GR) activity increased and glutathione -S transferase (GST) activity decreased, while ascorbate peroxidase (APX) activity did not change under drought stress in the tolerant cultivar. SOD, CAT and APX were decreased and GST activities were increased while GR did not change in 'Shemal'. Also SOD, APX and CAT activity increased by copper treatment alone in both cultivars. Otherwise combined treatment increased SOD, APX and CAT activity at all concentrations, but GR and GST activity increased only by (PEG+1.5 mM) treatment when compared with PEG treatment alone in sensitive ones. As a result, exogenous copper alleviated drought stress, while it induced an oxidative damage by increasing antioxidant enzyme activities differently from drought tolerance. Copper tolerance in maize is not a common response of its defense mechanism because of different response to copper and drought in the same cultivar.
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    PACLOBUTRAZOL DEPENDENT SALT TOLERANCE IS RELATED TO CLC1 AND NHX1 GENE EXPRESSION IN SOYBEAN PLANTS
    (Univ Life Sciences Lublin, 2022) Dinler, Burcu Seckin; Cetinkaya, Hatice; Sergiev, Iskren; Shopova, Elena; Todorova, Dessislava
    Paclobutrazol (PBZ) enhances plant resistance to salt stress in two ways: directly, by straight clearance of reactive oxygen species; and indirectly by enhancing antioxidant enzyme activity, photosynthetic efficiency, and metabolite content, and by regulating transcription factors associated with stress. However, the regulatory effects of PBZ under salt stress in soybean are still not well explained and need further investigation. With this aim, the combination effect of salinity (250 mM NaCl) and three different doses of PBZ (5, 10 and 20 ppm) on physiological, biochemical and molecular traits of soybean (Glycine max L.) leaves were studied in soil experiments. Furthermore, physiological parameters (relative growth rate, relative water content), chlorophyll, malondialdehyde (MDA), hydrogen peroxide (H2O2) content and as well as enzymatic antioxidants (SOD, POX, APX, CAT and GST), ion content (Na, Cl) and soybean Na+/H+ antiporter GmNHX1 and chloride channel GmCLC1 gene expressions were investigated. The results showed that PBZ caused a reduction in salt-induced damages and an increase in biomass yield, water status, and chlorophyll. Moreover, PBZ regulated enzymatic antioxidants and alleviated the oxidative damages under salinity. In this study, for a first time it was determined that PBZ increased both GmNHX1 (ABA dependent or independent) and GmCLC1 (ABA independent) gene expressions and reduced Na and Cl concentrations in soybean under salinity. In conclusion, PBZ plays a role as a regulator and stimulant in salt stress response by mostly regulating ion balance in soybean leaves.
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    PACLOBUTRAZOL INDUCED NON-ENZYMATIC ANTIOXIDANTS AND POLYAMINE LEVELS IN SOYBEAN PLANTS GROWN UNDER SALINITY STRESS
    (Nature Research Centre, 2021) Dinler, Burcu Seckin; Cetinkaya, Hatice; Sergiev, Iskren; Shopova, Elena; Todorova, Dessislava
    Paclobutrazol (PBZ) is a member of the triazole family of plant growth regulators and is known to protect crops from environmental stresses such as salinity and drought. It plays a role in maintaining water balance, photosynthesis capacity and enhancing antioxidant enzyme activities. Despite the well-documented effects of PBZ on antioxidant defence in soybean plants, the changes in non-enzymatic antioxidants and endogenous polyamines in the PBZ-treated plants grown under salinity stress are still not studied. Herewith, the study aimed to clarify the effects of PBZ on these molecules. For this purpose, the combined effect of salt (250 mM NaCl) and three different concentrations of PBZ (5, 10 and 20 ppm) on soybean (Glycine max L.) plants were studied. Proline, hydroxyl radical (OH.) scavenging capacity, non-enzymatic antioxidants (anthocyanin, flavonoid, phenolic and free thiol-containing compounds) and polyamines spermine, spermidine, and putrescine were investigated in the treated plants. We found that the PBZ (10 ppm) treatment was the most effective concentration to counteract oxidative stress due to NaCl in soybean seedlings. It significantly increased hydroxyl radical scavenging activity, proline, total phenolics, flavonoids, and conjugated polyamine content compared to those found in salt-treated plants only. For the first time, our study showed that PBZ could induce the non-enzymatic antioxidant defence in soybean plants grown under salt stress conditions. © 2021, Nature Research Centre. All rights reserved.
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    The Effect of Different Doses of Salt Stress on Germination and Emergence in Cannabis ( Cannabis sativa L.) Seed Treated with Pre-Salicylic Acid
    (Inst Tecnologia Parana, 2024) Gul, Volkan; Sefaoglu, Firat; Cetinkaya, Hatice; Dinler, Burcu Seckin
    It is known that salinity stress, one of the abiotic stress factors, significantly limits the germination, growth, development, and crop yield of plants. Therefore, this study was conducted to evaluate the effects of salinity (control, 50, 100 ve 150 mM) on seed germination and the effect of salicylic acid (control, 0.25, 0.50, 0.75 ve 1.00 mM) on seed germination to improve salt tolerance in cannabis seeds. The physiological characteristics of the plant, such as germination percentage, germination duration, germination index, radicle length, plumule length, wet radicle weight, dry radicle weight, wet plumule weight, and dry plumule weight, were analyzed. Depending on the salinity application dose, it was observed that there was a significant decrease in the germination parameters of cannabis seeds compared to the control. It was observed that salicylic acid treatments under salinity stress positively affected all the characters examined and reduced germination arrest due to increasing concentration levels. Although it is recommended to prepare seeds with 0.5 mM salicylic acid pre-application dose against salt stress of the cannabis plant,it is essential to expand the studies on its transfer to practice. As a result, salicylic acid will provide positive results that can be transferred to practice by increasing the resistance of cannabis plants against salinity, especially in agricultural soils with salt problems, as it will be more sensitive to pests and diseases.
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    The regulation of glutathione s-transferases by gibberellic acid application in salt treated maize leaves
    (Springer, 2023) Dinler, Burcu Seckin; Cetinkaya, Hatice; Secgin, Zafer
    Plant hormones and antioxidant system changes occur during plants' exposure to stress conditions. Although the interactions of some plant hormones (abscisic acid, salicylic acid, jasmonic acid, nitric oxide, and ethylene) with the glutathione s-transferase (GST) enzyme, which is one of the antioxidant enzymes, have already been reported, the influence of gibberellic acid (GA(3)) on this enzyme under saline conditions has not yet been reported. Plant material for the experiments was obtained from M14G144 cultivar of maize (Zea mays L.) plants grown as a soil culture in growth chambers at 22 & DEG;C, 65-70% moisture, 16-h light/8-h dark conditions, and with full strength Hoagland solution for 8 days under controlled growth conditions. Then, the plants were exposed to salt stress (350 mM NaCl and 100, 300, and 500 ppm GA(3)) simultaneously. In maize leaves, GA(3) treatment alleviated the physiological parameters under salt stress. Specifically, the treatments with 100 and 500 ppm of GA(3) were able to trigger GST enzyme and isoenzyme activities as well as hydrogen sulfide accumulation and anthocyanin content, although the lowest malondialdehyde, hydrogen peroxide, and superoxide radical content were under the treatment of 300 ppm of GA(3). Besides this, GST gene expression levels were found to be upregulated between 1.5 and fourfold higher in all the plants treated with GA(3) at different concentrations in proportion to salt stress. These results first indicated that the reason for the changes in GA(3)-treated plants was the stimulating role of this hormone to maintain GST regulation in maize plants.
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    Treatment with auxin and paclobutrazol mediates ROS regulation, antioxidant defence system and cell wall response in salt treated soybean
    (Soc Botanica Sao Paulo, 2024) Ayvaci, Ufuk; Koc, Fatma Nur; Cetinkaya, Hatice; Dinler, Burcu Seckin
    Auxin (IAA) and paclobutrazol (PBZ) play important role in resisting abiotic stress for plants. However, the effects of combination of these regulators in plants under salinity remained obscure. In the current study, the role of 50 ppm IAA and 10 ppm PBZ on mitigating salt stress (200 and 300 mM NaCl) was investigated in soybean (Glycine max L. cv. Planet). We identified that IAA or PBZ and IAA + PBZ improved the physiological parameters that were damaged by salinity but PBZ performed best as observed by scanning election microscopy (SEM). However, IAA was more succesful to induce some antioxidant enzymes (superoxide dismutase, catalase, ascorbat peroxidase, peroxidase), although both of them reduced or did not affect GSH- related enzymes (dehydroascorbate reductase, monodehydroascorbate reductase, glutathione-s-transfease, glutathione reductase, glutathione peroxidase). Besides this, combination of IAA and PBZ treatment showed the lowest MDA with inhibited salt stress induced oxidative damage. Additionally, PBZ was more effective against as IAA to reduce the pectin methyl esterase (PME) and phenylalanine ammonium lipase (PAL) enzyme activities as well as decreased arabinose content, while they were increased with salinity. IAA or PBZ increased lignin content and led to reduced loosening in roots, while IAA performed best. Overall, this study firstly presents that these regulators (50 ppm IAA; 10 ppm PBZ) could be used together to increase salt tolerance in soybean plants via regulating physiological and biochemical metabolism, antioxidant defense system and cell wall modified parameters.