A Novel Protocol for Stevia rebaudiana (Bert.) Regeneration

Stevia rebaudiana Bertoni has sweet substances (stevioside) in its leaves that are free of calories and their consumption is beneficial for diabetic patients and is also helpful in high blood pressure also. Because of low capability in seed germination, tissue culture is an appropriate method for propagation of this plant. In the current study, optimization of stevia in vitro cultivation via direct organogenesis with different explants, light intensities and plant hormones has been examined. These treatments included BAP (at 0.5, 1, 1.5 and 2mg/l) in combination with 2,4-D, IBA and NAA (each with concentrations of 0.1, 0.2 and 0.5mg/l) and different light intensities (Dark, 2000, 4000 and 6000 lux). MS was utilized as a basal medium. Results indicated the highest rate of organogenesis (85%) occurred on the axillary buds explants with a medium containing 1.5mg/l BAP + 0.1mg/l NAA under 6000 lux light intensity. Also, the highest range of primary organ per explant (42) with 0.3cm length was achieved at this condition. The most efficient medium for rhizogenesis i.e. 100% root production along with the highest root number (11 with approximately 7.13cm length) was obtained in presence of activated charcoal and 1mg/l of IBA. At the end of rhizogenesis experiments, the plantlet length and node multiplicity were 12.8cm and 7 respectively. Greenhouse cultivation of these plantlets was successful.