Iron nano modulated growth and biosynthesis of steviol glycosides in Stevia rebaudiana

Application of nanomaterials is becoming the most effective strategy of elicitation to produce a desirable level of plant biomass with complex medicinal compounds. This study was, designed to check the influence of commercial iron nanoparticles (FeNPs) on physical growth characteristics, antioxidant status and production of steviol glycosides of in vitro grown Stevia rebaudiana. Results indicated that lower concentrations of FeNPs (45 µg/L) had a positive influence on morphological growth parameters. At a higher dose (90, and 135 µg/L) FeNPs in culture media were found detrimental to growth characteristics and development. Furthermore, the stress caused by FeNPs at 135 µg/L in cultures produced higher levels of total phenolic content (3.2 ± 0.042 mg/g dry weight: DW), total flavonoid content (1.6 ± 0.022 mg/g DW and antioxidant activity (73 ± 4.6%). In addition, plants grown in the presence of FeNPs at 90 µg/L resulted in higher enzymatic antioxidant activities (SOD = 3.2 ± 0.042 U/mg; POD = 2.1 ± 0.026 U/mg; CAT = 2.6 ± 0.034 U/mg and APx = 3.3 ± 0.043 U/mg), respectively. Furthermore, exposure to a low dose of FeNPs (45 µg/L) exhibited the maximum amount of stevioside (stevioside: 4.2 ± 0.058 mg/g (DW) and rebaudioside A: 4.9 ± 0.068 mg/g DW) as compared to high doses. The current investigation confirms the effectiveness of FeNPs in growth media and offers a suitable prospect for commercially desirable production of S. rebaudiana biomass with higher sweet glycosides profiles in vitro.