Effect of salicylic acid on stevioside and rebaudioside A production and transcription of biosynthetic genes in in vitro culture of Stevia rebaudiana

S. rebaudiana produces steviol glycosides including stevioside and rebaudioside A that are valuable as low calorie sweeteners. The objective of this study was to investigate the effects of salicylic acid elicitation and sampling times on the improvment of stevioside and rebaudioside A production and KA۱۳H, UGT۷۴G۱ and UGT۷۶G۱ genes expression. The results showed that the addition of different concentrations of salicylic acid had different effects on stevioside and rebaudioside A production in a dosage-dependent manner. Among different concentrations of salicylic acid the highest amount of stevioside was ۳۸.۳۳ mg/g DW and the highest amount of rebaudioside A was ۲.۹۳ mg/g DW, observed ۹۶ h after elicitation with ۹۰ mg/L and ۴۸ h after elicitation with ۶۰ mg/L salicylic acid, respectively. Elicitation with salicylic acid increased KA۱۳H and UGT۷۴G۱ genes expressions and decreased UTG۷۶G۱ gene expression. The correlation analysis indicated that, KA۱۳H gene expression had a positive correlation with stevioside production. The UGT۷۴G۱ gene expression had a positive correlation with stevioside production and a negative correlation with rebaudioside A production. The UGT۷۶G۱ gene expression had a positive correlation with rebaudioside A and negative correlation with stevioside production. The qRT-PCR analysis indicated that, by increasing stevioside production under salicylic acid elicitation, the KA۱۳H and UGT۷۴G۱ genes expression increased and UGT۷۶G۱ gene expression decreased.

Keywords:

Elicitation , Gene expression , Rebaudioside A , Stevia rebausiana , Stevioside