As a secondary metabolite, sesquiterpenes are not only have important functions in plant defense and signaling, but also play potential roles in basic materials for pharmaceuticals, cosmetic and flavor. As a traditional Chinese herbal medicine, Senecio scandens exhibits effects of anti-inflammatory and immunosuppressive, as well as invigorating the blood and removing extravasated blood. Over 600 sesquiterpenes with diverse structures were isolated from S. scandens and related species in the same genus. To characterize sesquiterpenes synthesis, two FPS genes(SsFPS1 and SsFPS2) were identified in S. scandens through transcriptomic analysis. Bioinformatic analysis showed that both SsFPSs have conserved motifs for FPS function. Both SsFPSs exhibited constitutive gene expression in S. scandens tissues and SsFPS2 accumulated higher transcript in leaves and roots than SsFPS1. Meanwhile consistent with constitutive sesquiterpene accumulation in S.scandens tissues, most of these sesquiterpenes were detected in leaves and roots more than stems and flowers. Recombinant expression through Escherichia coli metabolic engineering, SsFPS1 or SsFPS2 was co-transformed with ZmTPS11(maize β-macrocarpene synthase) into BL21 competent cells. The results showed that the content of β-macrocarpene was increased by co-transformation with SsFPSs. It is demonstrated that SsFPS1 and SsFPS2 catalyzed E,E-FPP formation and provided FPP precursor for downstream sesquiterpene synthases. Characterization of SsFPSs provided the foundation for the exploration of biosynthesis of sesquiterpenoid with diverse structures and potential pharmaceutical values in S.scandens, and provide an important theoretical basis for the development of S. scandens abundant resources.
Cloning, Molecular ; Gene Expression Profiling ; Geranyltranstransferase ; Medicine, Chinese Traditional ; Senecio/genetics* ; Sesquiterpenes

As a traditional Chinese medicine, Senecio scandens is rich in important compounds such as flavonoid and sesquiterpenoid. Based on the transcriptome data of S. scandens, 15 candidate reference genes were selected including ABCT, ACT1, ACT2, ACT3, ACBP, ARF, ATPS, EF-H, EF-1α, ETIF, GAPDH, GTPB, MPS, UCE and 60S. Firstly, 9 candidate genes with relatively stable expressions such as ACT1, ACBP, ARF, ATPS, EF-1α, GAPDH, MPS, UCE and 60S were screened from different tissues of S. scandens by RT-PCR. Then, qRT-PCR was used to quantitatively analyze gene expression of these nine candidates in S. scandens with or without stress treatments. Further analysis of these gene expression data by geNorm and NormFinder showed that ACT1 exhibited the stablest expression in all samples and could serve as a reference gene for future study of S. scandens, and provide an endogenous control for gene expression analysis.
Gene Expression Profiling ; Genes, Plant ; Medicine, Chinese Traditional ; Plants, Medicinal ; genetics ; Reference Standards ; Reverse Transcriptase Polymerase Chain Reaction ; Senecio ; genetics ; Transcriptome