Integrated Transcriptomic and Metabolomic Analyses Reveal Selenium Nanoparticle-Associated Alkaloid Accumulation in...

Stemona tuberosa Lour. is a traditional Chinese medicinal plant whose tuberous roots contain alkaloids with antitussive and antimicrobial activities. This study investigated the effects of selenium nanoparticles (SeNPs) on alkaloid accumulation in S. tuberosa. Plants were treated with different SeNP concentrations (0, 10, 20, 40, and 80 mg L^-1) for 10, 20, 30, and 40 days. Alkaloid and total selenium contents in tuberous roots were determined, and integrated metabolomic and transcriptomic analyses were performed. SeNPs induced concentration- and time-dependent changes in alkaloid accumulation, with the highest level observed at 20 mg L^-1 after 30 days. Total selenium content generally increased with treatment duration. Based on these results, the Se20 treatment at 30 days was selected for omics analyses. Metabolomic profiling revealed significant alterations in amino acids, organic acids, and alkaloids. Differential metabolites were mainly enriched in isoquinoline alkaloid biosynthesis, purine metabolism, and cofactor biosynthesis pathways. A total of 55 differential alkaloids were identified, of which 39 differed significantly between Se0 and Se20, including 29 upregulated and 10 downregulated compounds. Transcriptomic analysis showed upregulation of PPO and TAT and downregulation of NCS. In addition, transcription factors from the AP2/ERF, bHLH, and MYB families were differentially expressed. These results suggest that SeNPs promote alkaloid accumulation by modulating precursor metabolism and key biosynthetic pathways. Overall, this study provides insights into the molecular basis of SeNP-mediated alkaloid accumulation and supports the cultivation of selenium-enriched medicinal plants.