Fungal elicitor-based improvement of steviol glycoside production in Stevia rebaudiana Bertoni cell suspension cultures

Stevia rebaudiana Bertoni is a perennial plant having medicinal importance in pharmaceutical and food industries. It is widely used as a sugar alternative, and its sweetening characteristics are due to the presence of steviol glycoside. This research work was conducted to evaluate the efficiency of Fo47 endophytic strain of Fusarium oxysporum crude extract as an elicitor for the enhancement of steviol glycoside contents in S. rebaudiana callus and cell suspension cultures. F. oxysporum is an ascomycete fungus and its metabolites act as signaling molecule those trigger the production of secondary metabolites. For this investigation, callus and suspension cultures were subjected to varying concentrations (0, 1, 2, 3, 4 and 5 mgL − 1 ) of fungal extract derived from F. oxysporum . After thirty days of calli and twenty days of cell suspension culture extract treatment, morphological parameters were evaluated along with total chlorophyll contents, antioxidant enzymes and steviol glycoside contents. The maximum fresh (3.74, 3.94 g) and dry weight (0.35, 0.39 g) of calli and cell suspension, respectively was observed by using 4 mgL − 1 of F. oxysporum extract. Similarly, maximum chlorophyll content (0.68 mg g −1 fresh weight), catalase (9.09 units/mL of enzyme), peroxidase activity (2.77 mg g − 1 ) and soluble sugars (17.63 mg g − 1 ) of calli was also obtained at 4 mgL − 1 . However, maximum catalase (9.19 units/mL of enzyme), peroxidase activity (2.87 mg g − 1 ), and soluble sugars (18.21 g) of cell suspension cultures was obtained on 3 mgL − 1 of extract. The maximum yield of steviol glycosides content (stevioside: 11.13 mg g −1 DW; rebaudioside: A 31.39 mg g − 1 DW) in callus (stevioside: 13.95 mg g − 1 DW; rebaudioside A: 33.76 mg g − 1 DW) and cell suspension cultures was recorded at 4 mgL − 1 of crude extract. This study may provide useful information for industrial production of natural sweeteners from S. rebaudiana cell culture by using fungal extract.