Optimization of elicitation and precursor feeding for enhancement of in vitro production of diosgenin in shoot cultures of Dioscorea deltoidea

Dioscorea deltoidea (Family: Dioscoreaceae) is a critically endangered medicinal plant used in the pharmaceutical industry for the production of steroidal drugs, including cortisone, contraceptives, and sex hormones. This study explored the effects of various elicitors—salicylic acid (SA), methyl jasmonate (MeJa), jasmonic acid (JA), and abscisic acid (ABA), along with precursors (squalene, β-sitosterol, and cholesterol) on diosgenin synthesis in D. deltoidea shoot cultures. The results demonstrated that precursors significantly enhanced diosgenin production compared to elicitors. SA (200 µM) resulted in the highest diosgenin content (0.912% DW) after 4 h of exposure, while MeJa (100 µM) produced 0.814% DW after 8 h. Among the precursors, β-sitosterol (200 µM) yielded the highest diosgenin content (1.006% DW), followed by squalene (100 µM) at 0.947% DW after 5 days. Cholesterol showed lower diosgenin production, though it was still higher than in control cultures. Response Surface Methodology (RSM) was applied to determine the optimal concentrations of elicitors and precursors, revealing that the combination of 165 µM SA and 150 µM β-sitosterol resulted in the highest diosgenin yield (1.321% DW) and biomass production (1.958 g). These findings highlight the significant influence of elicitors and precursors on diosgenin accumulation, offering valuable insights for optimizing its industrial production.