The effect of selenium concentration on growth and stress markers in two Iranian strains of Dunaliella salina Teodoresco

Abstract

Selenium toxicity and selenium stress were investigated by comparison of molecular, physiological and genetic response in plants and algae recently. In this study, the phycological responses of two strains of Dunaliella salina (Gavkhooni and Maharloo) to different Na2SeO3 concentrations (0, 0.25, 0.75, 1, 1.5, 2 mg/l) were evaluated. Our results showed that carotenoid, astaxanthin, total antioxidant, proline content, and activity of enzymatic antioxidant (especially CAT and APX) increased by adding low concentration of Na2SeO3 (up to 1 mg/l) in the medium, which also was accompanied by increase cell division, chlorophyll pigments content in both strains. Selenite concentration higher than 1 mg/l in the medium, resulted a decrease in the activity of SOD (about 19%, and 41% in Gavkhooni and Maharloo treated with 2 mg/l Na2SeO3 respectively), CAT, and APX as well as the total antioxidant capacity (about 39%, and 23% in Gavkhooni and Maharloo treated with 2 mg/l Na2SeO3 respectively) that led to increased electrolyte leakage (98%, and 62% increase in Gavkhooni and Maharloo treated with 2 mg/l Na2SeO3 respectively)and MDA content (45% and 31% in Gavkhooni and Maharloo at highest Na2SeO3 concentration respectively)in both strains. Consequently, the cell number and growth of both strains decreased in the high selenium concentration medium. The cell division of Gavkhooni strain was statistically higher than Maharloo strain under low level of selenium. Moreover, a delay in the growth of Maharloo strain was illustrated under selenium stress. Generally, it can be concluded that the better growth of Gavkhooni under low level of Se can probably be caused by the increase in the power of total antioxidant, enzymatic and non-enzymatic antioxidants.