Growth and Steviol Glycoside Content of Stevia rebaudiana Bertoni in the Thin-Layer Liquid Culture Treated with Late-Stage Gibberellin Biosynthesis Inhibitors

Stevia (Stevia rebaudiana Bertoni) is a source of steviol glycoside, a natural sweetener which has almost zero calorie and glycemic index. Steviol glycoside shares the same precursor with gibberellin (GA), ent-kaurenoic acid. Therefore, to manipulate the biosynthesis pathway of steviol glycoside, a gradient of late-stage GA biosynthesis inhibitors, Daminozide and Prohexadione-Ca, was applied to the thin-layer liquid culture of stevia, which was 10 mL of liquid medium in the 100-mL Erlenmeyer flask. The culture was incubated for 3 weeks, followed by the observation of growth parameters and steviol glycoside content. Results showed that both Daminozide and Prohexadione-Ca significantly increased the steviol glycoside content, indicating that the disruption of GA biosynthesis could divert the metabolic pathway toward steviol glycoside production. However, the inhibition effect of Prohexadione-Ca was stronger than Daminozide, and caused poor growth of stevia plantlets. Therefore, Daminozide at the concentrations of 10 ppm and 20 ppm was potential to modulate steviol glycoside production from the stevia culture.