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    Modulation of osmotic adjustment and enzymatic antioxidant profiling in Apera intermedia exposed to salt stress
    (Tubitak Scientific & Technological Research Council Turkey, 2014) Yildiztugay, Evren; Ozfidan Konakci, Ceyda; Kucukoduk, Mustafa; Duran, Yagmur
    The effects of salinity on growth, osmotic adjustment, and antioxidative responses were evaluated in Apera intermedia. For this purpose, 30-day-old plants were irrigated every other day with Hoagland nutrient solution containing 0, 150, 300, or 600 mM NaCl for 7 and 14 days. The results showed inhibition of growth, relative growth rate, relative water content, and osmotic potential with increasing NaCl concentration. Increased Na+, Cl-, and Na+/K+ ratio and decreased K+ and Ca2+ were determined with increasing NaCl concentrations. The activities of superoxide dismutase and ascorbate peroxidase were conspicuously enhanced at 150 mM NaCl, but activities of catalase, peroxidase, and NADPH oxidase were reduced in a concentration/time-dependent manner. The highest proline, choline, and glycine betaine accumulation assisted higher osmotic adjustment and maintenance of water status at 150 mM. However, the destructive effects of 300-600 mM were more severe in comparison to lower salinity, depending on the increase of hydrogen peroxide and thiobarbituric acid reactive substances for 14 days. After exposure to 300 and 600 mM, only ascorbate peroxidase and glutathione reductase were induced, but they were not sufficient to scavenge H2O2.
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    Variations in osmotic adjustment and water relations of Sphaerophysa kotschyana: Glycine betaine, proline and choline accumulation in response to salinity
    (Springeropen, 2014) Yildiztugay, Evren; Ozfidan-Konakci, Ceyda; Kucukoduk, Mustafa; Duran, Yagmur
    Background: Sphaerophysa kotschyana Boiss. is naturally distributed in overly salty regions. The key to the completion of the life cycles of S. kotschyana in harsh saline soils may be hidden in changes of its osmo-protectants, but there is currently no information about the interaction between osmotic adjustment and water relations in adaptation to saline conditions. The aim of this article was to determine growth, relative growth rate (RGR), relative water content (RWC), osmotic potential (psi(Pi)), photosynthetic efficiency (F-v/F-m), thiobarbituric acid-reactive substances (TBARS) and osmo-protectant contents [proline (Pro), choline (Cho) and glycine betaine (GB)] in S. kotschyana leaves and roots exposed to 0, 150 or 300 mM NaCl for 7 and 14 d (days). Results: The results clearly showed that the reductions in growth, RWC, F-v/F-m, RGR and psi(Pi) were more pronounced at 300 mM, especially after 14 d. In the same group, the highest increase in TBARS was recorded in roots (126%) and leaves (31%). The induction at 150 mM was not as high. Therefore, roots appear to be the most vulnerable part of this plant. Moreover, S. kotschyana was able to withstand short-term low salinity. Conclusions: The osmo-protectant accumulation in S. kotschyana as a salinity acclimation or adaptation was sufficient for toleration of low salt concentration (150 mM). In contrast, the plants exposed to the highest NaCl concentration (300 mM) were not able to maintain the ability to prevent water loss because of further decrease in root/shoot ratio of fresh weight (FW) and dry weight (DW), RWC and RGR.