Genome-wide analysis of TPS family reveals kaurene synthase-like genes in Isodon rubescens f. lushanensis

Abstract

Isodon rubescens f. lushanensis, a typical form of I. rubescens , is characterized by its natural deficiency in oridonin and the presence of a unique ent-kaurane diterpenoid, lushanrubescensin. To elucidate the molecular basis underlying the distinct chemical profiles between I. rubescens f. lushanensis and I. rubescens (Hemsl.) Hara, we conducted a comprehensive analysis utilizing high-quality genomic and transcriptomic data of I. rubescens f. lushanensis. Through a genome-wide survey, our study identified 83 terpene synthase ( TPS ) genes, including 13 TPS -C and 9 TPS-e /f subfamily genes, which are implicated in diterpenoid biosynthesis. By integrating conserved motif analysis, differential expression profiling (FPKM), and RT-qPCR validation, we successfully screened key candidate genes. Subsequent heterologous expression in Saccharomyces cerevisiae enabled the functional characterization of five diterpene synthase genes, specifically CPS and KSL enzymes, involved in the central modules of diterpenoid synthesis. These findings not only expand the repertoire of known biosynthetic genes in I. rubescens but also offer valuable insights into the divergent biosynthetic pathways of oridonin and lushanrubescensin, paving the way for future metabolic engineering and synthetic biology studies.