Biomass Yield and Steviol Glycoside Production in Callus and Suspension Culture of Stevia rebaudiana Treated with Proline and Polyethylene Glycol.

Abstract

Enhanced production of steviol glycosides (SGs) was observed in callus and suspension culture of Stevia rebaudiana treated with proline and polyethylene glycol (PEG). To study their effect, yellow-green and compact calli obtained from in vitro raised Stevia leaves were sub-cultured on MS medium supplemented with 2.0mg l(-1) NAA and different concentrations of proline (2.5-10mM) and PEG (2.5-10%) for 2weeks, and incubated at 24 ± 1°C and 22.4μmol m(-2) s(-1) light intensity provided by white fluorescent tubes for 16h. Callus and suspension culture biomass (i.e. both fresh and dry weight content) was increased with 5mM proline and 5% PEG, while at further higher concentrations, they got reduced. Further, quantification of SGs content in callus (collected at 15th day) and suspension culture (collected at 10th and 15th day) treated with and without elicitors was analysed by HPLC. It was observed that chemical stress enhanced the production of SGs significantly. In callus, the content of SGs increased from 0.27 (control) to 1.09 and 1.83% with 7.5mM proline and 5% PEG, respectively, which was about 4.0 and 7.0 times higher than control. However, in the case of suspension culture, the same concentrations of proline and polyethylene glycol enhanced the SG content from 1.36 (control) to 5.03 and 6.38%, respectively, on 10th day which were 3.7 times and 4.7 times higher than control.