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Öğe Abiotic stress of ZnO-PEG, ZnO-PVP, CuO-PEG and CuO-PVP nanoparticles enhance growth, sweetener compounds and antioxidant activities in shoots of Stevia rebaudiana Bertoni(Institution of Engineering and Technology, 2017) Javed, Rabia; Zia, Muhammad; Yücesan, Buhara; Gürel, EkremNanoparticles are known to play remarkable role as abiotic stress elicitors in plants. This study reports the comparative analysis of effects produced by capped [zinc oxide (ZnO)-polyethylene glycol (PEG), ZnO-polyvinyl pyrrolidone (PVP), copper oxide (CuO)-PEG, CuO-PVP] and uncapped (ZnO and CuO) nanoparticles on the medicinal plant, Stevia rebaudiana raised in vitro for the production of commercially important sweetener compounds. In context of shoot organogenesis, ZnO-PEG, ZnO-PVP, CuO-PEG, CuO-PVP were employed to the growth medium that resulted in increased growth parameters, and larger content of steviol glycosides as compared to the shoots raised in medium containing ZnO and CuO, revealed by high-performance liquid chromatography. In the meanwhile, non-enzymatic antioxidant activities including total phenolic content, total flavonoid content, total antioxidant capacity, total reducing power and 2,2-diphenyl-1-picryl hydrazyl-free radical scavenging activity were calculated and showed comparatively greater amounts in shoots grown in medium containing capped ZnO or CuO nanoparticles. Furthermore, the ZnO and its derivatives revealed to be more reactive at 1 mg/l of concentration. Whereas, the CuO and its derivatives produced greater response on Stevia at 10 mg/l concentration of nanoparticles. This study paves the way for more such studies encompassing capped and uncapped nanoparticles and their ultimate effect on in-vitro grown plant tissues for the production of active metabolites on industrial scale. © The Institution of Engineering and Technology 2017.Öğe CuO nanoparticles significantly influence in vitro culture, steviol glycosides, and antioxidant activities of Stevia rebaudiana Bertoni(Springer Netherlands, 2017) Javed, Rabia; Mohamed, Aliyu; Yücesan, Bahtiyar; Gürel, Ekrem; Kausar, Rukhsana; Zia, MohammadCopper oxide (CuO) nanoparticles (NPs) synthesized through co-precipitation method were employed in MS media during in vitro culture of Stevia rebaudiana. Physiological characteristics, production of steviol glycosides, and antioxidative parameters were investigated in regenerated plants. CuO NPs had crystalline monoclinic cubic cuprous oxides with average size 47 nm. The NPs were applied at 0, 0.1, 1.0, 10, 100 and 1000 mg/L in MS media for direct organogenesis of S. rebaudiana from nodal segments. Shoot organogenesis was found highest (88.5%) at 10 mg/L CuO and average shoot length, mean number of shoot per explant, and fresh weight were also found significantly higher at the same concentration. High performance liquid chromatography (HPLC) illustrated significant rise of bioactive major steviol glycosides (rebaudioside A and stevioside) at 10 mg/L CuO NPs in MS media. The oxidative stress produced by CuO nanoparticles on S. rebaudiana was affirmed by antioxidant activities i.e. total antioxidant activity (TAC), total reducing power (TRP) and 2,2-diphenyl-1-picryl hydrazyl (DPPH)-free radical scavenging activity. The oxidative stress generated by NPs involved production of antioxidative molecules total phenolic content (TPC), total flavonoid content (TFC) depending on NPs concentration. The study concludes that copper oxide nanoparticles functions as a stimulator of bioactive components productions, and can be employed in in vitro batch cultures. © 2017, Springer Science+Business Media B.V.Öğe Effect of zinc oxide (ZnO) nanoparticles on physiology and steviol glycosides production in micropropagated shoots of Stevia rebaudiana Bertoni(Elsevier France-Editions Scientifiques Medicales Elsevier, 2017) Javed, Rabia; Usman, Muhammad; Yücesan, Buhara; Zia, Muhammad; Gürel, EkremThis study aims to address the effects of different concentrations (0, 0.1, 1.0, 10, 100 or 1000 mg L-1) of engineered zinc oxide (ZnO) nanoparticles (34 nm in size) on growth parameters, steviol glycosides (rebaudioside A and stevioside) production and antioxidant activities in the tissue culture grown shoots of Stevia rebaudiana Bertoni. The highest percentage of shoot formation (89.6%) at 1 mg L-1 of ZnO nanoparticles concentration suggests a positive influence of ZnO nanoparticles on S. rebaudiana growth as compared to other treatments with or without ZnO nanoparticles. Additionally, HPLC results illustrate a significant enhancement of steviol glycosides (almost doubled as compared to the control) in micro propagated shoots grown under an oxidative stress of 1 mg L-1 of ZnO nanoparticles. This finding is further affirmed by an increased 2,2-diphenyl-1-picryl hydrazyl (DPPH) scavenging activity, total antioxidant capacity, total reducing power, total flavonoid content and total phenolic content, with an ascending oxidative pressure and generation of reactive oxygen species (ROS). However, the antioxidant activities, formation of secondary metabolites and the physiological parameters showed a sudden decline after crossing a threshold of 1 mg L-1 concentration of ZnO nanoparticles and falls to a minimum at 1000 mg L-1, elucidating maximum phytotoxic effect of ZnO nanoparticles at this concentration. This is the first study evaluating both the favorable and adverse effects of ZnO nanoparticles employed to a highly valuable medicinal plant, S. rebaudiana. (C) 2016 Elsevier Masson SAS. All rights reserved.Öğe Elicitation of Secondary Metabolites in Callus Cultures of Stevia rebaudiana Bertoni Grown Under ZnO and CuO Nanoparticles Stress(Springer India, 2018) Javed, Rabia; Yücesan, Buhara; Zia, Muhammad; Gürel, EkremAccumulation of secondary metabolites in medicinal plants by giving abiotic/biotic stress is, nowadays, an active area of research. This study reports the inoculation of ZnO and CuO nanoparticles in Murashige and Skoog (MS) medium having plant growth regulators for the regeneration of callus from leaf explants of medicinal plant, Stevia rebaudiana. Presence of ZnO and CuO nanoparticles in different concentrations results in conferring different kinds of physiology in different regenerants. 1 and 10 mg/L have been declared the best ZnO and CuO nanoparticles concentrations regarding various physiological parameters. Steviol glycosides have not been detected in any callus treatment. Moreover, the phytochemical characteristics of S. rebaudiana under different ZnO and CuO nanoparticles concentrations have been exploited. The highest amount of total phenolic content (TPC), total flavonoid content (TFC), total antioxidant capacity (TAC) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity has been obtained at 100 mg/L of ZnO nanoparticles, whereas TPC, TAC, TRP and DPPH free radical scavenging activity have been achieved highest at 10 mg/L concentration of CuO nanoparticles. However, the highest TRP in the context of ZnO and the highest TFC regarding CuO have been achieved at 50 and 100 mg/L, respectively. This clearly indicates that CuO nanoparticles are more toxic to Stevia callus as compared to ZnO nanoparticles, and opens avenues for future studies utilizing ZnO or CuO nanoparticles for the enhancement of commercially important secondary metabolites in different medicinal plants. © 2017, Society for Sugar Research & Promotion.Öğe Hydrogen peroxide-induced steviol glycosides accumulation and enhancement of antioxidant activities in leaf tissues of stevia rebaudiana bertoni(Springer India, 2018) Javed, Rabia; Yücesan, Bahtiyar Buhara; Gürel, EkremHydrogen peroxide (H2O2) functions as an abiotic stress elicitor for plants. In this study, the effect of oxidative stress caused by H2O2 on steviol glycosides (SGs) production and antioxidant activities of an in vitro grown antidiabetic plant, Stevia rebaudiana, has been investigated. Direct shoot organogenesis was performed, and after 4 weeks of culture, the shoots of S. rebaudiana were transferred to MS medium containing H2O2 (10 or 20 mM) and incubated in growth room for 6 h. It resulted in increased SGs production, such as rebaudioside A (Reb-A) and stevioside (ST), and enhancement of total phenolic content, total flavonoid content, total antioxidant capacity, total reducing power and DPPH free radical scavenging activity when compared with control. The results clearly showed highest amount of SGs produced in MS medium containing 10 mM H2O2 [producing 2.97% Reb-A and 2.32% ST (w/w)], followed by the medium employing 20 mM H2O2 and control group. It is also evident that H2O2 pre-treatment caused significant increase in non-enzymatic antioxidants that play defensive role against an oxidative stress induced by H2O2. The described protocol has a great potential to be utilized for Reb-A production on commercial scale.Öğe Impact of Stevia rebaudiana Culturing in Liquid Medium: Elevation of Yield and Biomass, Mitigation of Steviol Glycosides(Giunti, 2022) Javed, Rabia; Yücesan, BuharaAn efficient micropropagation system is developed by culturing nodal segments containing the axillary shoot buds on liquid Murashige and Skoog (MS) medium. Direct shoot and root formation are highly effective in both solid and liquid MS media without any plant growth regulators (PGRs). Interestingly, a significant difference in yield is obtained between solid and liquid cultures. It is revealed that a relatively higher amount of plant biomass is obtained after culturing for 4 weeks in a liquid MS medium. However, the shoots produced on solid MS medium produce a remarkable decline in all physiological parameters. On contrary, the bioactive steviol glycosides (rebaudioside-A and stevioside) content is higher in shoots grown in solid MS on a comparative basis, which could be compensated by higher yield. After hardening off, all the regenerants are effectively grown in the field with a negligible loss (<1 %), and steviol glycosides spectra is again obtained by conducting high-performance liquid chromatography (HPLC) analysis after 10 weeks of the plantation. This method has great potential to be applied on large scale in bioreactors. © Pakistan Academy of SciencesÖğe Nanoelicitation: A Promising and Emerging Technology for Triggering the Sustainable In Vitro Production of Secondary Metabolites in Medicinal Plants(Springer Nature, 2022) Javed, Rabia; Yucesan, Buhara; Zia, Muhammad; Gurel, EkremTo obtain larger amounts of secondary metabolites is essentially needed by the global industrial market that is not feasible by traditional methods because these are time-consuming and result in eradication of plant stock by overexploitation. Therefore, in vitro culturing techniques are adopted to obtain the maximum quantity of secondary metabolites in a minimum time. Elicitors are key players for getting desired yields of secondary metabolites in plants. Eliciting the in vitro cell and tissue cultures is an efficient approach for the production of medicinally important plant secondary metabolites. Different parameters of optimized micropropagation protocols are exploited to be used as elicitors for further enhancement of secondary metabolites from medicinal plant species. The secondary metabolites produced by the plant cells include phenolics, flavonoids, alkaloids, terpenoids, and tannins. These metabolites are boosted under stressful conditions, whether biotic or abiotic in origin. The potential role of nanoparticles in the enhancement of secondary metabolic products in medicinal plants is a recent hot topic in the field of medicinal plant biotechnology. Nanoparticles have evolved as potent novel elicitors that significantly stimulate medicinal plant secondary metabolism. Various kinds of nanoparticles including metallic and metallic oxide nanoparticles and carbon-based nanomaterials are believed to induce abiotic stress to medicinal plants under in vitro conditions by which plant defense system is elicited, triggering biochemical as well as physiological responses, consequently producing enhanced and sustainable quantities of secondary metabolites. These industrially important bioactive metabolites are beneficial for the prevention of multiple diseases in the health-care system. Therefore, nanoelicitation should be applied as an effective tool for ameliorated stimulation and accumulation of secondary metabolites. However, in some cases, after the efficient uptake and translocation, nanoparticles produce deleterious effects causing phytotoxicity. © The Editor(s) (if applicable) and The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2022.Öğe Salt stress by NaCl alters the physiology and biochemistry of tissue culture-grown Stevia rebaudiana Bertoni(2019) Javed, Rabia; Gürel, EkremThis study reports the response to salinity stress (100 mM, 200 mM, and 300 mM NaCl concentration) exposure of the commercially valuable medicinal plant Stevia rebaudiana during micropropagation for 4 weeks. The significant enhancement of physiological parameters, steviol glycosides (SGs), i.e. rebaudioside A and stevioside, as examined by high-performance liquid chromatography, and nonenzymatic antioxidant activities, i.e. total phenolic content, total flavonoid content, total antioxidant capacity, total reducing power, and DPPH-free radical scavenging activity, was observed during the shoot formation process under up to 100 mM NaCl stress. Callus formation produced similar results regarding physiology and antioxidant assays, except that it produced merely a negligible amount of SGs. Contrarily, root formation showed marked susceptibility to 100 mM, 200 mM, and 300 mM NaCl concentrations and reduced growth parameters, sweetening compounds, and secondary metabolites. Hence, NaCl plays the role of abiotic stress elicitor, causing accumulation of reactive oxygen species and thus altering metabolic processes and physiology of Stevia under in vitro culture conditions.
