Integrated transcriptomic and metabolomic analyses reveal the regulatory network underlying NtGSTU10-mediated nicotine synthesis and transport in tobacco.

Nicotine is the major alkaloid in tobacco and plays a key role in determining tobacco quality. Previous studies have shown that overexpression of NtGSTU10 enhances nicotine accumulation in tobacco hybrids; however, the molecular mechanisms underlying this process remain largely unclear. In this study, we investigated the regulatory role of NtGSTU10 in nicotine synthesis and distribution using integrated transcriptomic and metabolomic analyses in NtGSTU10-overexpressing tobacco plants. Nicotine content and distribution between roots and leaves were quantified, and global transcriptional and metabolic profiles were analyzed to reveal molecular changes associated with NtGSTU10 overexpression. The results showed that NtGSTU10 overexpression was associated with increased nicotine accumulation in leaves and reduced nicotine levels in roots, resulting in significantly higher nicotine transport coefficients compared with wild-type plants. Transcriptomic analysis revealed coordinated changes in genes involved in nicotine biosynthesis, transport, and secondary metabolism. Metabolomic profiling indicated significant alterations in amino acid metabolism, nicotinic acid and nicotinamide metabolism, purine metabolism, sugar metabolism, and alkaloid biosynthesis pathways. Integrated transcriptome–metabolome analysis further identified coordinated regulation of glutathione metabolism, ABC transporters, and MATE transporter–encoding genes. Overall, these results reveal a regulatory network associated with NtGSTU10-mediated nicotine biosynthesis and transport, providing new insights into the molecular mechanisms underlying nicotine metabolism in tobacco.