Effect of salinity on Brassica rapa var. toria (BRSRT) under selenium defence: A trial to assess the protective role of selenium

Abstract

The present study assesses the role of selenium, an antioxidant in salt-stressed plants. A hydroponic trial of sodium selenate (Na₂SeO₄) on the growth, oxidative stress and antioxidant protection system of <em>Brassica rapa </em>var. <em>toria</em> (BRSRT) plant was studied. 40 µmol and 100 µmol of Na₂SeO₄were hydroponically applied to BRSRT roots with 50 mmol and 100 mmol sodium chloride (NaCl) for 12 days. Plant growth, biomass production and photosynthetic pigments at 100 mmol salt stress was inhibited while oxidative stress indicators, for example, hydrogen peroxide and lipid peroxidation were stimulated. Supplementation of 40 µmol Na₂SeO₄with 50 mmol and 100 mmol NaCl improved growth, photosynthetic pigments and acted as an antioxidant by inhibiting lipid peroxidation and increasing superoxide dismutase, ascorbate peroxidase, catalase, glutathione peroxidase, glutathione reductase activities. The in-gel assays also showed enhanced activities of these enzymes. At 100 µmol concentration, selenium under salt stress, repressed growth and expression of antioxidant enzymes and stimulated oxidative stress with enhanced glutathione peroxidase activity. Under consolidated stress treatment, an addition of 40 µmol Na₂SeO₄ was the most effective for both NaCl concentrations. The finding reveals that the optimal selenium supplementation presents a promising potential for use in conditions of relatively high levels of NaCl stress for BRSRT seedlings.