Identification and characterization of stevia (Stevia rebaudiana Bert.) lines with enhanced steviol glycosides derived from gamma ray-induced in vitro mutagenesis

In the present study, in vitro nodal segments of stevia (Stevia rebaudiana Bertoni), irradiated with an optimized gamma-ray dose (18 Gy), were transferred to a shoot-root regeneration medium and subcultured from M1V1 up to M1V6 generations (each with a 4-week growth period). On the basis of morphological appearance, five Bidhan Stevia rebaudiana variant lines (BSRV1-BSRV5) were selected for further analyses. All major in vitro growth traits and steviol glycoside content analyses were carried out for BSRV1-BSRV5 along with the control (non-irradiated) line. The BSRV1 exhibited exceptional growth performance and biomass production, followed by BSRV2 and BSRV3 when compared to the control. Histology exhibited distinct differences in cellular and tissue levels among that variants. During high-performance liquid chromatography analysis, rebaudioside-A [66.00 mg/g dry weight (DW)] and stevioside (6.60 mg/g DW) contents were recorded to be maximum in BSRV1 followed by BSRV2, BSRV3, and BSRV4 against the control line (42.19 mg/g DW and 3.83 mg/g DW, respectively). The identified variants with distinct morphology and ameliorated steviol glycoside content should be of high potential for future breeding programs. In vitro-induced mutagenesis using gamma rays resulted in novel stevia variants with significant morpho-histological differences and exhibited 1.6-fold and 1.7-fold increments in rebaudioside-A and stevioside.