SUSTAINABLE MICROPROPAGATION OF SELECTED Stevia rebaudiana Bertoni GENOTYPES

Stevia rebaudiana Bertoni is a perennial plant belonging to Asteraceae family and its leaves contain steviol glycosides (SGs) that are 150 to 300 times sweeter than sucrose. The sweeteners obtained from S. rebaudiana can be safely used by diabetics as insulin secretion is not required during digestion of this sweetener. As it has zero calories, it is also used in diet products. Adaptation studies for Stevia conducted in Antalya, Turkey have shown that the stevia plant could easily be cultivated as a perennial. However, the lack of a sustainable vegetative propagation method creates a significant problem for stevia production. In the generatively populations, homogeneity and therefore quality are decreased because of cross-pollination. Stevia, as a self-incompatible and cross-pollinated species, has been shown to have very high genetic diversity. Therefore, development of a sustainable in vitro propagation method to prevent genetic heterogeneity of selected varieties is crucial for stevia cultivation. The aim of this study was to evaluate 2 different gelling agents (plant agar and Gelrite) and 20 different growth regulators combinations. The results demonstrated an approximately 200-fold multiplication rate obtained within 13 weeks using MS medium supplemented with 0.5 mg·dm–3 BAP and 0.25 mg·dm–3 kinetin and solidified with Gelrite. Average stevioside and rebaudioside A contents in in vitro propagated plant samples were found to be 8.1% and 8.6%, respectively.