Molecular cloning and functional analysis of a 10-epi-junenol synthase from Inula hupehensis

Biosynthesis of bridged tricyclic sesquiterpenes in Inula lineariifolia

Presilphiperfolane-type sesquiterpenes represent a unique group of atypical sesquiterpenoids characterized by their distinctive tricyclic structure. They have significant potential as lead compounds for pharmaceutical and agrochemical development. Herein, we utilized a transcriptomic approach to identify a terpene synthase (TPS) gene responsible for the biosynthesis of rare presilphiperfolane-type sesquiterpenes in Inula lineariifolia, designated as IlTPS1. Through phylogenetic analysis, we have identified the evolutionary conservation of key motifs, including RR(x)8W, DDxxD, and NSE/DTE in IlTPS1, which are shared with other tricyclic sesquiterpene synthases in the TPS-a subfamily of Asteraceae plants. Subsequent biochemical characterization of recombinant IlTPS1 revealed it to be a multiproduct enzyme responsible for the synthesis of various tricyclic sesquiterpene alcohols from farnesyl diphosphate (FPP), resulting in production of seven distinct sesquiterpenes. Mass spectrometry and nuclear magnetic resonance (NMR) spectrometry identified presilphiperfolan-8β-ol and presilphiperfol-7-ene as predominant products. Furthermore, biological activity assays revealed that the products from IlTPS1 exhibited a potent antifungal activity against Nigrospora oryzae. Our study represents a significant advancement as it not only functionally identifies the first step enzyme in presilphiperfolane biosynthesis but also establishes the heterologous bioproduction of these unique sesquiterpenes.

Effects of Cabya (Piper retrofractum Vahl.) Fruit Developmental Stage on VOCs

The differences in VOCs can affect the flavor and medicinal value of cabya, and the flavor changes that occur in stages as the fruit develops are currently unknown. In order to investigate the influence of the developmental stage on the aroma composition of cabya essential oil, VOCs at each of the four developmental stages were analyzed by steam distillation (SD) extraction combined with GC-MS detection. The similarities and differences in fruit composition among the developmental stages were evaluated using hierarchical cluster analysis (HCA) and principal component analysis (PCA). A total of 60 VOCs, mainly alcohols, alkenes and alkanes, were identified across all of the developmental stages. The most acidic substances were detected in phase A and have a high medicinal value. There was no significant difference between the B and C phases, and the alcohols in those phases mainly promoted terpenoid synthesis in the D phase. Constituents during the D phase were mainly alkenes, at 57.14%, which contributed significantly to the aroma of the essential oil. PCA and HCA both were able to effectively differentiate the cabya fruit developmental stages based on the SD-GC-MS data. In summary, this study investigated the flavor variation characteristics and the diversity of VOCs in cabya fruits at different developmental stages, and its findings can provide a reference for developing essential oil products for different uses and determining appropriate stages for harvesting cabya resources.