Engineering and Optimization of the Salidroside Production in Tobacco Cells by Reconstructed Biosynthetic Genes from <i>Rhodiola rosea</i>

Salidroside, a tyrosine-derived bioactive product, originates from the <i>Rhodiola</i> genus and has various medicinal properties. However, the surge in global demand requires exploration of more efficient and sustainable approaches to produce salidroside. This study reconstructed three functional enzymes in tobacco cells to produce salidroside using endogenous l-tyrosine. Under the optimized two-stage protocol (1% sucrose in the production medium; 11 days of culture), salidroside accumulation reached a maximum of 377.53 μg per gram of HHU cells in fresh weight. Neither precursor feeding (100 mg/L shikimate) nor various elicitors (e.g., MeJA, SA, and ABA) provided any further enhancement. Comparative transcriptomic analysis revealed that two DAHPS transcripts (107797958 and 107817203) were upregulated more than 2-fold, indicating that the reconstructed pathway boosts endogenous l-tyrosine flux, and elicitation and precursor feeding strategies could not enhance salidroside accumulation. Meanwhile, comparative transcriptomic analysis revealed that the reconstructed pathway could upregulate crucial gene expression in endogenous l-tyrosine biosynthesis. This study evaluates tobacco cells as biofactories to produce salidroside and lays the foundation for the biosynthesis engineering of other heterologous metabolites.