Identification of candidate genes involved in isoquinoline alkaloids biosynthesis in Dactylicapnos scandens by transcriptome analysis

Abstract

Dactylicapnos scandens (D. Don) Hutch (Papaveraceae) is a well-known traditional Chinese herb used for treatment of hypertension, inflammation, bleeding and pain for centuries. Although the major bioactive components in this herb are considered as isoquinoline alkaloids (IQAs), little is known about molecular basis of their biosynthesis. Here, we carried out transcriptomic analysis of roots, leaves and stems of D. scandens, and obtained a total of 96,741 unigenes. Based on gene expression and phylogenetic relationship, we proposed the biosynthetic pathways of isocorydine, corydine, glaucine and sinomenine, and identified 67 unigenes encoding enzymes potentially involved in biosynthesis of IQAs in D. scandens. High performance liquid chromatography analysis demonstrated that while isocorydine is the most abundant IQA in D. scandens, the last O-methylation biosynthesis step remains unclear. Further enzyme activity assay, for the first time, characterized a gene encoding O- methyltransferase (DsOMT), which catalyzes O-methylation at C7 of (S)-corytuberine to form isocorydine. We also identified candidate transcription factor genes belonging to WRKY and bHLH families that may be involved in the regulation of IQAs biosynthesis. Taken together, we first provided valuable genetic information for D. scandens, shedding light on candidate genes involved in IQA biosynthesis, which will be critical for further gene functional characterization.

Identification and Characterization of Genes Involved in Benzylisoquinoline Alkaloid Biosynthesis in Coptis Species

“…In the present study, we carried out a comprehensive transcriptome study of C. chinensis and C. teeta by means of next-generation RNA-seq technology. Combining our present results with previous reports ( Rüffer et al, 1983 ; Ikezawa et al, 2008 ; Ziegler et al, 2009 ; Hagel et al, 2015 ; He et al, 2017 ), we propose the biosynthetic pathways for berberine, palmatine, jatrorrhizine, coptisine, columbamine, magnoflorine, and epiberberine, and identify candidate genes that are involved in the biosynthesis of BIAs. Moreover, we characterized 6OMT and norcoclaurine-7OMT (7OMT), which catalyze O -methylation at C6 on ( S )-norcoclaurine to yield ( S )-coclaurine, along with a smaller amount of O -methylation at C7, thereby forming its isomer, isococlaurine.…”

“…Detection was performed at 345 nm ( Zhang G.H. et al, 2015 ; He et al, 2017 ). The content of berberine, coptisine, jatrorrhizine, palmatine, and epiberberine were calculated from standard curves.…”

Molecular Origins of Functional Diversity in Benzylisoquinoline Alkaloid Methyltransferases

“…Whereas the enzyme efficiently catalyzes the signature RNMT-like activity and might contribute to quaternary aporphine biosynthesis, it also uniquely accepts pavinan alkaloids and is thought to participate in the biosynthesis of N -methylescholzidine, an uncommon BIA, which accumulates in Thalictrum spp (Liscombe et al, 2009). In D. scandens , a corytuberine 7- O -methyltransferase (DsC7OMT) was identified, and preliminary analysis linked it to the biosynthesis of isocorydine (He et al, 2017).…”

Rifamycin congeners kanglemycins are active against rifampicin-resistant bacteria via a distinct mechanism

“…The kng gene cluster also contains a set of genes ( kng30 , kng34A/B , and kng35) that we predict are involved in producing the K-acid; however, the genes responsible for installing the gem-dimethyl functionality on the succinic acid are not bioinformatically obvious. An O -methyltransferase, encoded by kng24 , and an additional cytochrome P450, encoded by kng28 , may participate in generating the methylenedioxy bridge found on the K-sugar as well as the Kang V2 ring system 27 , 28 .…”