Transcriptomic analysis of Atractylodes lancea (Thunb.) DC under methyl jasmonate induction reveals the terpene synthase genes related to sesquiterpenoid biosynthesis

Methyl jasmonate (MeJA) serves as a potent elicitor of plant specialized metabolism, including terpenoid biosynthesis. The medicinal rhizome of Atractylodes lancea, renowned in traditional Chinese medicine, synthesizes pharmaceutically active sesquiterpenoids responsible for its therapeutic efficacy against rheumatic diseases, digestive disorders, and night blindness. However, the molecular understanding of MeJA-mediated sesquiterpene biosynthesis in A. lancea is not clear. Thus, it is important to explore the molecular mechanism and genes involved in sesquiterpene biosynthesis pathway underlying the response of A. lancea to MeJA. Combining MeJA elicitation with transcriptome profiling, we identified 25 sesqui-terpenoids synthase (AlTPS) gene in A. lancea via KEGG enrichment analysis and conserved motif analysis. Correlation analysis between DEGs and sesquiterpenoid accumulation, coupled with phylogenetic assessment, identified AlTPS7 and AlTPS8 as prime candidates, showing close homology to the characterized β-eudesmol synthase ZmZSS2. Functional characterization revealed that AlTPS8 could catalyze the conversion of FPP into β-caryophyllene, with a small amount of α-caryophyllene as a byproduct, whereas AlTPS7 was enzymatically inactive. Notably, quantitative analysis revealed AlTPS8’s superior catalytic efficiency, producing β-caryophyllene at 3.14-fold higher titers (0.36 ± 0.04 mg/L) than our previously characterized AlTPS6*, as quantified by in vivo product accumulation. Structural modeling and mutagenesis analyses revealed four key divergent residues (ALA398, SER402, THR449, ASN525) in AlTPS6* that regulate functional divergence, with the substitution of ASN525 to ASP being critical for enhancing catalytic efficiency. These results provide mechanistic insights into MeJA-responsive sesquiterpenoid biosynthesis in A. lancea and a genetic toolkit for metabolic engineering of high-value medicinal terpenoids.