Abstract
BackgroundThree species of wintersweets: Chimonanthus salicifolius S. Y. Hu, Chimonanthus zhejiangensis M. C. Liu and Chimonanthus grammalus M. C. Liu are widely distributed in China. The three wintersweets belonging to the genus of Chimonanthus that can synthesize abundant terpenoids that are beneficial to human health. Their buds and leaves are traditional Chinese herb applied by the ‘She’ ethnic minority in southeast of China. Squalene is a multi-functional and ubiquitous triterpene in plants, which is biosynthesized by squalene synthase (SQS) using farnesyl diphosphate (FPP) as the substrate. The synthesis of squalene in wintersweet was not clearly. This work would provide us much help to further understand the terpene metabolism in wintersweet and its health function to people at phytochemistry and molecular levels.ResultsIn this study, we identified squalene component in the extractions of leaves of three wintersweets and isolated SQS genes from leaf transcriptomes. The three SQSs were highly conservative, so CzSQS from C. zhejiangensis was just determined the enzymatic activity. The in vitro expressed CzSQS that deleted two transmembrane domains could catalyze FPP to generate squalene with the presence of NADPH and Mg2+.ConclusionsThe squalene was one of wintersweet leaves phytochemicals. The squalene synthases of three wintersweet plants were highly conserved. The CzSQS was capable to catalyze two FPP molecules to squalene.
Highlights
Wintersweet (Calycanthaceae) contains ten species belonging to three genera: Calycanthus L. contains three species distributed in America and Eastern Asia, Chimonanthus contains six species originated in China, and Idiospermum Blake contains a single species distributed in Australia (Christenhusz and Byng 2016)
Identification of squalene in leaves of wintersweet Squalene was not found in the volatiles of C. zhejiangensis leaves collected by the SPME and Super-Q using static and dynamic headspace methods, while it was detected by GC × GC-TOFMS in the leaf extractions of n-hexane, dichloromethane and ethyl acetate
The chromatogram peak area of the extractions of dichloromethane was the largest, which indicated that squalene was identified in all the extractions of Isolation of squalene synthase genes from wintersweet The full-length sequences of squalene synthase from C. salicifolius, C. zhejiangensis, C. grammalus were first identified by transcriptomic sequencing and further confirmed by PCR amplification and the NCBI accession numbers are MH277638, MH277639 and MH277637, respectively
Summary
Wintersweet (Calycanthaceae) contains ten species belonging to three genera: Calycanthus L. contains three species distributed in America and Eastern Asia, Chimonanthus contains six species originated in China, and Idiospermum Blake contains a single species distributed in Australia (Christenhusz and Byng 2016). The six species of Chimonanthus are further classified into aromatic type and nonaromatic type according to whether their leaves release aroma or not. C. Liu are aromatic type (Zhang and Shen 1999). C. Three species of wintersweets: Chimonanthus salicifolius S. The three wintersweets belonging to the genus of Chimonanthus that can synthesize abundant terpenoids that are beneficial to human health. Their buds and leaves are traditional Chinese herb applied by the ‘She’ ethnic minority in southeast of China. This work would provide us much help to further understand the terpene metabolism in wintersweet and its health function to people at phytochemistry and molecular levels
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