Direct Organogenesis of Stevia rebaudiana Bertoni Using Thin Cell Layer (TCL) Method

An effective protocol was established for the micropropagation of Stevia rebaudiana Bertoni (Asteraceae) through direct organogenesis using thin cell layer (TCL) method. Different concentrations (0, 2.22, 4.44, and 6.66 mu M) of exogenous growth regulators [Benzyladenine (BA) and (0, 2.26, 4.52, and 6.78 mu M) of 2,4-dichlorophenoxyacetic acid (2,4-D)] were evaluated in combination with transverse thin cell layers (tTCLs) of the hypocotyls of seedlings established in vitro in MS medium. The best organogenic response (31.16 shoots per tTCL explant) was obtained by applying 6.78 mu M of 2,4-D. The effect of incubation conditions on the morphogenetic responses was evaluated. Combination of conditions of photoperiod and complete darkness presented the best results in terms of the appearance of shoots vigor. Roots formed on 100 % of the shoots on using 1/2 MS without PGRs. Of the regenerated plants, 90 % acclimated successfully under greenhouse conditions.