Genetical Studies on Stevia Plants as a Natural Sweetners

The present investigation has been carried out to study morphological, cytological characters and the biochemical genetic variations of peroxidase isozymes of seven Stevia genotypes. Moreover, the tissue culture techniques were used to identify the best medium for callus induction and the regeneration using different concentrations of phytohormones to produce a high and more number of shoots and roots in each genotype. Drought stress was studied on cultivable calli of all genotypes as excreted by the effect of different concentrations of Polyethyleneglycol (PEG), using two procedures (Cyclic and Direct) and four concentrations of PEG, beside their control. The biochemical genetic variations of Peroxidase isozymes of the treated with PEG and untreated samples of Stevia genotypes were also investigation. The peroxidase isozymes were studied again in the in vitro (regenerated plant) and in vivo (mother plant which grown in green house). Examination of the chromosomal configuration of mitotic and meiotic stages using the divided cells of root tips and the pollen mother cells, had been achieved.