Impact of salt strength on in vitro propagation and rebaudioside A content in Stevia rebaudiana under semi-solid and liquid MS media

Stevia rebaudiana (Bertoni), commonly known as stevia, is a sought-after natural sweetener, but its conventional propagation methods are slow and inefficient. This study aims to enhance the in vitro culture for stevia by investigating the impact of different Murashige and Skoog (MS) medium salt strengths and plant growth hormones on growth and rebaudioside A content. Apical bud-containing shoot segments were used as explants and cultured on various semi-solid and liquid MS media formulations, incorporating cytokinins (BAP and Kin), auxins (NAA and IAA), and different MS major salt concentrations (MS full, ½ MS, and ¼ MS). Assessments of shoot growth parameters, root formation, and HPLC analysis for rebaudioside A content were conducted. The optimal conditions for in vitro growth was found to be in the ¼ MS + Kin 3 mg/L + NAA 0.1 mg/L (semi-solid) medium, resulting in significantly improved shoot growth and enhanced 30.04% rebaudioside A content. Genetic fidelity of regenerated plants was confirmed using RAPD and ISSR markers. These findings offer valuable insights for optimizing in vitro propagation of stevia and potentially enhancing rebaudioside A content.