Effect of Chemical Mutagen on Some Biochemical Properties of Stevia rebaudiana Bertoni

Induced mutagenesis causes an increase variation of some products with limited genetic resources. In this study, the antioxidant enzymes activity, biochemical properties and glycoside content of Stevia were assessed by EMS (chemical mutagen) based on two experiments as factorial with completely randomized design with three replications. The results of the first experiment showed that some properties of regenerated calli were influenced by different concentrations of EMS, different times of exposure and interactions of these two factors. Therefore, more EMS concentration and its duration of exposure indicated fewer regeneration rates and indices of the calcified masses. According to the second experiment, our data showed that EMS mutant activity was related to enzymatic activity and some biochemical properties of regenerated plants at a 1% significance level. Among the mutants, M10, M6, and M19 had the highest enzyme activity and M3 and M10 mutants with + 41.4 and +26.12% revealed the higher percentage of incremental changes in proline accumulation than the control sample. In addition, the highest amount of total protein was allocated to M16, M14 and M3 mutants (values of 0.69, 0.67 and 0.58 mg/g tissue texture, respectively) over the control sample (0.27 mg/ gram of tissue) and M8 mutant had the highest percentage of changes in the amount of stevioside (87.3%) and rebaudioside A (58.3%), respectively. Overall, significant changes were observed in the antioxidant activity and biochemical properties and the amount of sugary glycosides of regenerated plants that could be used to create plants with higher quality traits.