Physiochemical and transcriptional reprogramming of mild salinity mediated modulation of Steviol Glycoside biosynthesis in Stevia rebaudiana Bertoni

This study comprehensively analyzes transcriptional and physiochemical reprogramming in Stevia rebaudiana under mild salinity. The observed increase in overall SGs suggests that mild salinity promotes SG accumulation. Moreover, enhanced accumulation of osmolytes such as proline, total sugars, MDA indicates an enhanced adaptive capacity in response to mild salinity. Additionally, differential expression of key genes involved in SG biosynthesis (DXS, DXR, GGPS, KAO, UGT74G1, UGT76G1, UGT85C2) and physiological and biochemical responses (P5CS, SWEET, CAT, SOD, APX, SOS)) highlights a coordinated regulatory mechanism that supports adaptation under mild salinity. Furthermore, TFs such as bHLH, ERF, MYB, NAC and WRKY were predicted as potential regulatory hubs within the gene regulatory networks, emphasizing their significant role governing specailized secondary metabolism. Importantly, both genotypes exhibiting enhanced salt tolerance demonstrated a greater potential for SGs biosynthesis and accumulation under mild salinity. Overall, this study provides a valuable mechanistic insight into the elicitation effect of mild salinity on SG biosynthesis in S. rebaudiana, identifying key genes and regulatory factors that could be utilized to breed improved stevia cultivars for saline-prone agroecosystems.