Abstract
The use of colchicine to induce polyploids increases secondary metabolite production potential and has been used for many years for the production of valuable compounds in plants. This project took advantage of this method to increase the production of secondary metabolites in licorice. For this purpose, seeds of licorice, Glycyrrhiza glabra var. glandulifera, were treated with different concentrations of colchicine for 24 hours and then cultivated in vitro. After a month, the effect of colchicine on the cellular DNA level of cotyledons was analyzed by spectrophotometry and flow cytometry. For callus induction, root explants of one month old plantlets derived from colchicine treated seeds were transferred to MS medium containing growth regulators and the anthocyanin and glycyrrhizic acid levels of the callus tissues were measured after two months of growth. The total DNA content of plantlets derived from seeds treated with 0.05%, 0.08% and 0.1% of colchicine for 24 hours was increased significantly. Treated plants had increased numbers of larger stomata, significantly in those treated with 0.1% of colchicine for 24 hours. After colchicine treatment, the root, shoot and leaf thickness was found to be increased, while their length was decreased. Results of flow cytometry showed changes in ploidy level in plantlets obtained from treatment with 0.08% (mixoploids) and 0.1% (tetraploids) of colchicine. Anthocyanin level was significantly increased in callus obtained from plantlets treated with 0.08% of colchicine. The amount of glycyrrhizic acid in all treatments increased, especially in the 0.1 and 0.03% colchicine treatments and this seems to prove an increased production of metabolites in polyploid licorice tissues.