Acorus tatarinowii Schott is a traditional medicinal plant valued for its mosquito-repellent properties, which are attributed to its terpenoid constituents. HS-SPME-GC-MS analysis of different tissues and developmental stages revealed a complex volatile profile, with multiple terpenoids detected in the samples. Genome-wide characterization of the terpene synthase (TPS) family revealed that the TPS-a subfamily forms a gene cluster on chromosome 6, likely resulting from tandem duplication events followed by relaxed selection pressure in tandem repeat regions. Functional assays showed that only AtsTPS2 and AtsTPS8 exhibit sesquiterpene synthase activity. Under HS-SPME-GC-MS conditions, AtsTPS8 produced germacrene B (which is detected as γ -elemene), whereas AtsTPS2 produced germacrene A (which is detected as β -elemene), these detected signals were interpreted as products of heat-induced rearrangement during analysis. AtsTPS2 was selected for further study. Site-directed mutagenesis identified Lys461 as a critical residue regulating catalytic efficiency; compared with the wild type, the K461A mutant increased the yield of the detected product by 145%. Transient overexpression of AtsTPS2 in A. tatarinowii led to a 2.02-fold increase in the abundance of the detected product peak, and increased mosquito repellency to 83%. Furthermore, the MYC family transcription factor AtsMYC5 was found to repress AtsTPS2 expression by directly binding to its promoter. This study identifies AtsTPS2 as a sesquiterpene synthase in A. tatarinowii , clarifies its catalytic properties and AtsMYC5-mediated transcriptional regulation, and suggests that the corresponding sesquiterpene pathway contributes to mosquito repellency in this species.
Peng et al. (Wed,) studied this question.