Elicitation directed growth and production of steviol glycosides in the adventitious roots of Stevia rebaudiana Bertoni

Stevia rebaudiana Bertoni is an industrially important plant, commonly used as a natural sweetener plant. The sweetening potential is due to the presence of calorie free steviol glycosides (SGs), which are many folds sweeter than the normal sugar. The present study introduced a rapid approach for the in vitro formation of adventitious roots (AR) and production of SGs and other antioxidant compounds in S. rebaudiana. The results showed that pretreatment of leaf explants with notable elicitors like methyl jasmonate (Me-J; 0.5 mg/L) for 45 min, phenyl acetic acid (PAA; 1 mg/L) for 15 min and melatonine (Mel; 2 mg/L) for 15 min resulted in the highest AR induction frequencies of 88.1%, 87.6% and 86.6%, respectively in the culture media maintained in the presence of 6benzyladenine (BA; 2 mg/L). However, when the explants were exposed to higher doses of elicitors for longer duration, a significant decline in the AR induction and growth were observed. Further, Me-J induced AR cultures showed higher accumulation of the total phenolic content (TPC = 3.9 +/- 0.38 mg), total flavonoid content (TFC = 2.3 +/- 0.32 mg) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity (84 +/- 4.1%). Nonetheless, elevated levels of antioxidant enzymes were observed in the AR cultures induced by all the elicitors. Compared with other cell cultures, production of higher levels of sweet glycosides (stevioside: 4.2 +/- 0.18 mg/g dry weight (DW) and rebaudioside A: 6.5 +/- 0.34 mg/g DW) were recorded in the AR cultures established in response to Me-J. The present study has enough potential for the commercial production of sweet glycosides in Stevia rebaudiana.