Effects of polyploidy on response of Dunaliella salina to salinity

Abstract

In this study, effect of different percentages of polyploid cells of Dunaliella salina in culture medium, on growth and other biochemical parameters of algae under different salinity levels were investigated. The results indicated that concentration 3M NaCl is the optimal concentration of salt, since in this concentration, the highest enhancement in fresh and dry weight, chlorophyll and carotenoids, soluble sugar, glycerol, protein and starch content was observed in comparison with other concentrations. The amount of these metabolites declined in the concentrations under the optimum salinity. The least and highest amounts of MDA were observed at 1 and 4 M NaCl respectively. Polyploidy in optimum concentration of salt, caused further increment of the above growth parameters. In this relation, in most cases, treatment of 0.1% was more effective. The beneficial effects of polyploidy in non-optimal conditions were also found in some parameters such as biomass, chlorophyll, carotenoids, proteins and starch. The activity of antioxidant enzymes CAT, SOD and POD were maximum in 4 M NaCl. Polyploidy affected activity of these antioxidant enzymes in some concentrations of salt. Overall, our results suggest that the microalgae have significantly different responses to salt stress based on ploidy level of the algae.\n\nAbbreviations