Induction of Polyploidy by Colchicine on the Green Algae Dunaliella salina

In this study, induction of polyploidy by colchicine was investigated in Dunaliella salina. To induce polyploidy in the cells, different concentrations of colchicine (0.05, 0.1, 0.5 and 1%) were used in three periods of times 12, 24, and 36 h. Measurement of DNA content was done by Nano drop method. All concentrations of colchicine caused an increase in DNA content. Results showed that the highest value of DNA obtained related to algal cells were exposed to 1.0 and 0.5% colchicine for 36 h (0.213 g/L and 0.274 g/L, respectively), with respect to DNA content in control sample, these treatments caused induction of polyploidy in algal cells. Survival percentage of cells at all concentrations of colchicine significantly decreased. Based on obtained results from survival rate and DNA content, two concentrations of 0.1 and 0.5% colchicine were selected for other analysis. Colchicine treatments (0.1 and 0.5%) caused an increase in doubling time and specific growth rate declined in the treated algae. Pictures obtained by fluorescence microscopy and image analysis revealed a significant enhancement of the cell and nuclear size of the microalgae. Results of flow cytometry analysis indicated that percentage of polyploid cells in cultures treated by 0.1% colchicine was 58.26% and by 0.5% colchicine was 74.19%.