Antioxidant activity of in vitro propagated Stevia rebaudiana Bertoni plants of different origins

Authors: ELY ZAYOVA, IRA STANCHEVA, MARIA GENEVA, MARIA PETROVA, LYUDMILA DIMITROVA

Abstract: An efficient in vitro protocol for propagation of Stevia rebaudiana Bertoni is described. Multiple shoots were induced in vitro from shoot tip and nodal segments on Murashige and Skoog medium containing 6-benzylaminopurine, zeatin, or thidiazuron alone and in combination with naphthalene acetic acid or indole-3-acetic acid. A high frequency of shoot induction as well as maximum number of shoots per shoot tip explant was observed on Murashige and Skoog medium supplemented with 6-benzylaminopurine (1.0 mg L^{-1}) alone and combined with indole-3-acetic acid (0.1 mg L^{-1}). For root induction, in vitro shoots were transferred to rooting media containing naphthalene acetic acid, indole-3-acetic acid, or indole-3-butyric acid. The highest rooting frequency and the highest number of roots was observed in half-strength Murashige and Skoog medium supplemented with 0.1 mg L^{-1} indole-3-butyric acid. The rooted in vitro plants were successfully acclimatized in a growth chamber and transferred to the field. Leaf extracts of plants propagated in vitro and adapted to field conditions are characterized by high levels of water-soluble antioxidant capacity (expressed as equivalents of ascorbic acid), phenols, and flavonoids, and therefore by high total antioxidant potential, expressed as DPPH radical scavenging activity.

Keywords: Acclimatization, micropropagation, nodal segments, shoot tips

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