The effect of hydro and osmopriming on alfalfa seed germination and antioxidant defenses under salt stress

Seeds of two alfalfa (Medicago sativa L) varieties, cv. Hamedani and Yazdi, were used to investigate the effects of osmo- and hydro-priming on seed germination, growth parameters, biochemical changes and antioxidant enzymes activities under high-level salt concentration (150 mM NaCl) stress. Seeds were primed with water and mannitol (4%) for 12 h at 25 ± 1°C. Ten-day-old seedlings obtained from seeds primed with mannitol (4%) and water showed more growth with respect to root and shoot length in comparison with seedlings obtained from non-primed seeds. The results showed that germination percentage was significantly higher than that of the unprimed seeds after priming. The priming treatment significantly enhanced the activities of catalase (CAT), peroxidase (POD), superoxide dismutase (SOD) and proline content and reduced the malondialdehyde (MDA) accumulation and electrolyte leakage under the salt stress condition. The results suggested that osmo- and hydro-priming were effective methods to enhance the ability of salt tolerance and to improve seed germination and seedling growth of alfalfa under high salt concentration stress condition. It seems that, these priming methods could be applied in alfalfa production in high saline soils in the future.Key words: Alfalfa, antioxidant defenses, priming, salt stress

Effets of Silver Salt Concentrations on Green Synthesis of Silver Nanoparticles Using the Plant Nigella Saliva

Bio-inspired silver nanoparticles were synthesized with the aid of a novel method, using leaves of the plant Nigella sativa. After drying the leaves in air, they were first sweltered in boiling distilled water and the liquid was filtered subsequently. The result was the brothused to reduce solutions including various concentrations of silver nitrate in a proper amount of pH. The displayed UV–visible spectra identified formation of silver nanoparticles whenever the colorless initial acclimated mixture turned brown. The centrifuged powder samples were examined using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (FESEM) and energy dispersive X-ray diffraction analysis (EDX) methods. The results clearly revealed that the final particles of precipitated powder are high purity agglomerates of silver nanoparticles. Besides, the effects of various amounts of the silver salt on particle size of nano silver were studied, using a particle size analyzer. FTIR results also indicated the role of different functional groups in the synthetic process

Interaction effect of cadmium and salicylic acid on proline and enzymatic antioxidant in soybean

Possible mediatory role of salicylic acid in protecting soybean (Glycine max L.) plantlets against cadmium toxicity was investigated. Changes in growth, proline and soluble carbohydrates contents, lipid peroxidation and activities of H2O2 scavenging enzymes in salicylic acid (0.5 mM) treated plantlets of soybean in Hoagland’s solution containing 200 μM CdCl2 were monitored. Results showed that fresh and dry weight of shoots and roots were reduced while proline and soluble carbohydrates contents and lipid peroxidation in leaves of soybean treated with cadmium were significantly increased compared to controls. Guaiacol peroxidase (1.06±0.05, 1.65±0.22), ascorbate peroxidase (42.16±1.09, 57.2±1.68) and catalase (1729.66±20.13, 4345±230.5) activities were significantly enhanced for (-Cd-SA) and (+Cd-SA) treatments respectively. Lipid peroxidation and proline content were lowered by salicylic acid treatment, while soluble carbohydrates were increased. The activities of guaiacol peroxidase, ascorbate peroxidase and catalase were also lesser in leaves of salicylic acid-treated plants. Salicylic acid alleviated cadmium toxicity not only at the level of antioxidant defense, but also by affecting other mechanisms of detoxification

Silicon- induced nitric oxide burst modulates systemic defensive responses of Salvia officinalis under copper toxicity

In this study, the role of nitric oxide (NO) burst in modulating Si-induced defensive responses in leaves and roots of Salvia officinalis under copper (Cu) stress were investigated. The result showed that 400 μM Cu markedly reduced shoot dry weight, but increased electrolyte leakage (EL) in leaves and both Si and sodium nitroprusside (SNP as the NO donor) improved these attributes in a dose-dependent manner. Interestingly, Cu toxicity systemically boosted a NO burst in both roots and shoots and applying Si and SNP markedly intensified it. The application of Si and SNP alone as well as their combination improved growth parameters and systemically alleviated Cu-induced lipid peroxidation and H2O2 accumulation through lowering Cu accumulation, increasing proline content, enhancing the activities of catalase (CAT) and superoxide dismutase (SOD) in both roots and leaves and up-regulating expression of SOD gene in leaves of S. officinalis. NO generation was substantially arrested and the responses induced by Si were significantly suppressed by pretreatment with 2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxy l-3-oxide (cPTIO) as a NO scavenger, Nx-Nitro- L-arginine methyl ester hydrochloride (L-NAME) as a nitric oxide synthase inhibitor, and tungstate as a nitrate reductase inhibitor. These novel results indicate that Si can induce Cu tolerance through triggering NO generation which systemically modulates defensive reactions in both roots and leaves of Salvia officinalis. © 2021 Elsevier Masson SA