Response of Antioxidant Enzymes to Colchicine and PhytohormonesTreatments in Dunaliella salina

In this experiment, we compared the antioxidative response and biomass production of three ploidy levels induced by three colchicine concentrations (0, 0.1, and 0.5%) and the effects of different concentrations of two phytohormones (auxin and gibberellin) on D. salina. The fresh and dry weight of algae treated with colchicine significantly increased. Auxin (1μM) and gibberellin (10 μM) caused a further increase in biomass in colchicine-treated algae. Colchicine treatment induced catalase and superoxide dismutase activity, but peroxidase activity showed a decrease under this condition. Auxin only increased the superoxide dismutase activity at concentrations of 10 and 100 µM. The catalase activity decreased in the treated algae with 1 and 10 µM auxin. Different auxin concentrations caused an induction in the mentioned enzymes in the colchicine-treated algae. The most increase was observed in catalase activity by adding 1 µM auxin to the colchicine-treated algae. Gibberellin at concentrations of 1 and 10 µM induced peroxidase, catalase, and superoxide dismutase activity. Gibberellin caused a considerable increase in enzyme activity in colchicine-treated algae. The results show that polyploidy along with phytohormones increases the activity of antioxidant enzymes and thus gives the algae the potential for better stress resistance.