Comparative transcriptome analysis of sesquiterpene biosynthesis and functional characterization of sesquiterpene synthases in Leonurus sibiricus L

Main conclusionTwo sesquiterpene synthases were identified through comparative transcriptome analysis of Leonurus sibiricus. LsSqTPS2 could produce high titer of delta -cadinene in vivo which suggests the terpene specificity of L. sibiricus.AbstractLeonurus sibiricus L., a medicinal herb, is widely used in China due to its pharmacological activities. Cadinene type sesquiterpenes, one of major bioactive components mainly present in aerial parts of L. sibiricus, showed antibacterial, anti-inflammatory, antioxidant and antiproliferative properties. However, there is no report about the sesquiterpene biosynthesis in L. sibiricus. This study identified L. sibiricus sesquiterpene synthases (LsSqTPSs) through comparative transcriptome analysis of L. sibiricus leaf and root samples using the BGISEQ-500 sequencing technique. A total of 83,244 unigenes were obtained with an average length of 1025 bp. Among them, 50,356 unigenes (60.49%) acquired annotations according to the BLAST searching results. A total of 68 differentially expressed genes (DEGs) were potentially involved in the sesquiterpene biosynthesis. Furthermore, four candidate DEGs encoding LsSqTPSs were characterized. The enzymatic characterization in engineered yeast showed that LsSqTPS1 produced alpha -farnesene as the single product and LsSqTPS2 mainly produced 76.23 mg/L of delta -cadinene, which constituted the major component of L. sibiricus leaf essential oil. This work contributes to the investigation of sesquiterpene biosynthesis in L. sibiricus.

Automated summary

Through comparative transcriptome analysis, two sesquiterpene synthases were identified in Leonurus sibiricus. LsSqTPS2 was found to produce a high titer of δ-cadinene, which is the major component of L. sibiricus leaf essential oil. This study contributes to understanding sesquiterpene biosynthesis in L. sibiricus.