Integrated volatile metabolomic and transcriptomic analysis provides insights into the regulation of odor components...

Ferula (Apiaceae), a genus of perennial herbs with significant medicinal and culinary value, derives its characteristic odor primarily from volatile organic compounds (VOCs), particularly volatile sulfur compounds (VSCs) and terpenoids. Despite their economic importance, two critical gaps hinder targeted utilization: Ferula species-specific VOCs remains undocumented, and the metabolic pathways and key genes of VSCs and terpenoids in Ferula are still unclear.

Volatile metabolomic and transcriptomic analyses were performed on two species of Ferula-viz., Ferula sinkiangensis K. M. Shen (XJ, strong odor) and Ferula ferulaeoides (Steud.) Korov (DS, bland odor). A total of 561 VOCs were annotated, with VSCs dominating XJ (45.98%) and terpenoids prevailing in DS (44.01%). The results VSCs were the primary source of the strong odor in XJ. In total, 42,817 differentially expressed genes (DEGs) were identified between XJ and DS in this study. KEGG pathway enrichment analysis of DEGs revealed significant divergence in the biosynthetic pathways of VSCs and terpenoids between the two Ferula species. Integrative multi-omics analysis identified 87 genes linked to VSC biosynthesis and 54 regulatory genes governing terpenoid production. In XJ, elevated accumulation of VSCs was mechanistically associated with the synergistic upregulation of glutamate-cysteine ligase (GSH), γ-glutamyltransferase (GGT), and flavin monooxygenase (FMO). High levels of VSCs precursors (e.g., S-allyl-L-cysteine sulfoxide) and transcriptional activation of these genes strongly correlated with the species-specific pungent odor profile. In DS, geranylgeranyl diphosphate synthase (GGPS) and farnesyl pyrophosphate synthase (FDPS) were identified as key regulators of terpenoid biosynthesis.

The present study expands our knowledge of the volatile metabolic profiles of the two Ferula species and lays the foundation for further studies on the regulatory mechanisms of Ferula quality.