Trans-Zeatin Riboside enhanced plant regeneration and Auxins induced adventitious rooting in Stevia rebaudiana

Stevia rebaudiana is an economically important crop prized for its natural sweeteners. This study investigated the effects of trans-zeatin riboside (tZR) on plant regeneration in vertical and horizontal orientations, different Murashige and Skoog (MS) medium strengths concentration, and various auxins on adventitious root formation in Stevia rebaudiana cuttings. Direct organogenesis enabled efficient shoot regeneration, with the highest shoot proliferation rate (10.5 shoots/explant) achieved using 5 mg/L tZR in horizontal orientation after three weeks. Gibberellic acid (GA₃) further enhanced shoot elongation with a low concentration of GA₃ (0.5 mg/L) increased plant height, whereas a high GA₃ concentration cause abnormal growth and inhibit rooting. For root development, half-strength MS medium was optimal for rooting of cuttings, and half-strength MS with 1.0 mg/L α-naphthalene acetic acid (NAA) yielded the longest roots, while 1.0 mg/L indole-3-butyric acid (IBA) producing the highest root numbers and highest transplant survival rates compare to other auxins concentrations. Notably, adventitious roots also formed on hormone-free medium before successful soil acclimatization. This research establishes an efficient in vitro regeneration system for Stevia rebaudiana, offering practical applications for commercial propagation and biotechnological advancements.