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Öğe Exogenous jasmonic acid induces stress tolerance in tobacco (Nicotiana tabacum) exposed to imazapic(Academic Press Inc Elsevier Science, 2016) Kaya, Armagan; Doganlar, Zeynep BanuJasmonic acid am is one of the important phytohormones, regulating the stress responses as well as plant growth and development. The aim of this study is to determine the effects of exogenous JA application on stress responses of tobacco plant exposed to imazapic. In this study, phytotoxic responses resulting from both imazapic and imazapic combined with JA treatment are investigated comparatively for tobacco plants. For plants treated with imazapic at different concentrations (0.030, 0.060 and 0.120 mM), antioxidant enzyme activities (catalase, ascorbate peroxidase, glutathione S-transferase and glutathione reductase), carotenoids, glutathione and malondialdehyte (MDA) contents, jasmonic acid, abscisic acid and indole-3-acetic acid levels as well as herbicide residue amounts on leaves increased in general compared to the control group. In the plants treated with 45 mu M jasmonic acid, pigment content, antioxidant activity and phytohormone level increased whereas MDA content and the amount of herbicidal residue decreased compared to the non-treated plants. Our findings show that imazapic treatment induces some phytotoxic responses on tobacco leaves and that exogenous jasmonic acid treatment alleviates the negative effects of herbicide treatment by regulating these responses. (C) 2015 Elsevier Inc. All rights reserved.Öğe Melatonin improves the multiple stress tolerance in pepper (Capsicum annuum)(Elsevier, 2019) Kaya, Armagan; Doganlar, Zeynep BanuPlants are often simultaneously exposed to various abiotic stress factors such as herbicide and drought at agricultural areas. The aim of this study is to investigate the effects of pendimethaline (Pend) on pepper, which is a culture plant, to determine interaction of multiple stresses when Pend and drought stresses are applied simultaneously on pepper and also to establish how exogenous melatonin (MEL) application affects multiple stress interaction and antioxidant responses in pepper. The results of the study show that for peppers exposed to 10% polyethylene glycol (PEG) and Pend at different concentrations (8, 16 and 32 mM) both separately and simultaneously, total chlorophyll content and relative water content decreased while carotenoid, proline, glutathione, endogenous MEL and malondialdehyde contents, ascorbate peroxidase, glutathine S-transferase and glutathine reductase activities as well as mRNA levels increased. These changes were found to be more significant statistically for (Pend + PEG) groups treated with stress simtdtaneously. While malondialdehyde content decreased, compared to untreated plants, for plants pre-treated with 50 mu M MEL; relative water content, chlorophyll, carotenoid, proline, glutathione and endogenous MEL contents as well as niRNA levels and activities of anticacidant enzymes (ascorbate peroxidase, glutathine S-transferase and glutathine reductase) increased. Our findings show that both Pend and PEG created some phytotoxic responses on pepper plant and multiple stress treatment induced these responses. However, exogenous MEL application alleviated negative effects of herbicide and drought stresses by inducing antiwddant defense responses of pepper.Öğe Physiological and Genetic Effects of Imazamox Treatment on Imidazolinone-Sensitive and Resistant Sunflower Hybrids(Springer International Publishing Ag, 2020) Arda, Hayati; Kaya, Armagan; Alyuruk, GulcinUse of herbicides is one of the most preferred options for crop protection against weeds. Imazamox is an imidazolinone (IMI)-group herbicide, and even low concentrations of imazamox might exhibit high biological activities on soil and plants. Therefore, in contrast to the conventional types of sunflowers that are sensitive to IMI-group herbicides, sunflowers that are resistive to IMI-group herbicides were also developed in recent years. In this study, the effect of imazamox on some physiological and genetic parameters of two types of sunflowers that are sensitive and resistant to IMI-group herbicides is comparatively investigated. For this purpose, three concentrations of imazamox (0.82, 1.64 and 2.45 mM, respectively) were applied on the two types of sunflower (i.e. SN:8 as IMI-sensitive type and SN:9 as IMI-resistant type, respectively). In addition, the physiological and molecular effects of IMI on antioxidant enzymes (such as superoxide dismutase (SOD), catalase, glutathione S-transferase (GST)), heat shock proteins (such as HSP26, HSP60, HSP70), phenolic contents (coumaric acid, caffeic acid, ferulic acid), phytohormone levels (indole-3-acetic acid, jasmonic acid (JA), salicylic acid (SA)) and accumulation of pesticides in the leaf tissue of sunflowers were analysed by qRT-PCR and LC MS/MS analysis. In this study, the pesticide concentration of resistant-type SN9 was significantly greater than that of SN8 with the application of 1.64-2.45 mM of imazamox, and the total pesticide amounts were 1.6 and 1.8 times significantly higher in leaf tissues, respectively. This pesticide accumulation led to an imbalance in the phytohormone and phenolic levels, increased levels of unfolded or misfolded proteins, and selective reduction of the GST, SA and JA levels in the two types of sunflowers. However, SN9 significantly responded to the pesticide accumulation via the overexpression of mitochondrial chaperone HSP60 (16.15-fold) and stress-specific HSP70 (54.46-fold), as well as higher SOD expression and SA and JA levels. In particular, by the application of high-dose IMI, our data revealed strong protein chaperone response, a high level of SOD expression, and finally the crosstalk of SA and JA, and these physiological and molecular phenomena can be indicative of pesticide-induced stress in SN9. The study suggested that high-concentration imazamox treatment induces some physiological and genetic changes at the phytotoxic level on not only IMI sensitive type but also resistant type.