Modulation of osmotic adjustment and enzymatic antioxidant profiling in Apera intermedia exposed to salt stress


Abstract: 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 Ca^{2+} 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 H_{2}O_{2}.

Keywords: Antioxidant defense system, Apera, osmotic adjustment, salt stress

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