Tissue culture and production of volatile secondary metabolites from callus of stevia rebaudiana at different c 4ombination of plant growth regulators

Stevia rebaudiana Bert (Asteraceae) is a herbaceous plant with sweet leaves, which are the source of sweetener products. The present study focuses on effects of different combination of plant growth regulators on callus induction, callus cell growth and regeneration and volatile constituents from callus of stevia in tissue culture condition. The results of present study have shown that callus formation promoted in all of media contained phytohormones of different auxin/cytokinin based combinations. However, NAA/BA combinations are significantly more effective in callus initiation and the highest amount of callus was obtained in medium supplemented with 1.5:2 mg/L of NAA/BA. It was revealed that shoot induction in callus occurred at hormonal treatments as IBA/BA and IBA/KIN (0.5:1.5 mgl-1). High rooting obtained in media supplemented with NAA/KIN (1.5:0.5 mgl-1). The results of GC-MS analyses of volatile constituents of calli showed that the callus oil was obtained in media supplemented with NAA/Kin (1.5:0.5 mgl-1). The NAA/Kin treatment with 1:0.5 mgl-1 concentration was dominated with squalene (40.50%) as main compound. The callus formed in media contained NAA/BA was enriched with Tricosane (38.57%). In addition, phytol (11.69%, 6.92%) was regarded as major constituent of the oil obtained from cultures supplemented with IBA/Kin and IBA/BA, respectively. It was concluded that there was a considerable differences in the essential oil profile of callus induced from different hormonal combinations. It is thought that various hormonal treatments may result in changes in metabolic pathways.