Abstract
In Vitro Propagation Potential of Stevia Rebaudiana Bertoni and Its Adaptation to Tokat Province
Stevia rebaudiana is a compelling plant in the world due to its natural and zero-calorie sweetener. Low germination rate of the seeds of this species limited its commercial production on especially non-habitat countries, including Turkey. In the current study, contribution of gibberellic acid on the germination of stevia seeds and indirect organogenesis protocols were tested for propagation of stevia seedlings. Production of Steviol glucosides with cell suspension culture in bioreactor were also tested in the current study. The entire seedlings provided from the seeds and callus culture were used to test the adaptation success of stevia to Tokat province climate condition. The results of the study indicated that 50 mg/l gibberellic acid has important contribution to seed germination and development of the stevia seedlings. The best callus induction and growth from stevia leaves took place under NAA (10.0 mg/l) and BAP (8.0 mg/l) hormonal concentrations. BAP (2mg/l) and IAA (2mg/l) hormones were more effective for shoot and root regenerations from callus culture, respectively. Stevia grown well in both greenhouse and field trials and reached its flowering time in 150 days in Tokat conditions. Fresh weight of the leaves collected in the field was 4.8 ton/hectare in the study. This result indicated that stevia is highly adaptive to Tokat climatic conditions and could be produced in commercial scale in the region. Cell suspension culture of stevia in bioreactor indicated fivefold increase in cell content in 15 days. Unfortunately, steviol glucoside content of cell suspension culture (< 2 mg/g.dry cell weight) was quite smaller than its content in the leaves (>40mg/g. dry leaf) grown under field and greenhouse conditions. This is the first report evaluating production of steviol glucosides with in vitro propagation techniques and ex vitro adaptation studies in Turkey.
Keywords
Stevia rebaudiana, steviol glucoside, tissue culture, adaptation
