[Transcriptome analysis of rhizome of Polygonatum cyrtonema and identification of candidate genes involved in biosynthetic pathway of steroidal saponin]

To enrich the transcriptome data in rhizome of Polygonatum cyrtonema seedlings, identify candidate functional genes involved in steroidal saponin biosynthesis and provide genetic resources for the research on anabolism pathway and regulatory mechanism of active components in P. cyrtonema, Illumina platform was applied to perform transcriptomic sequencing of rhizome of P. cyrtonema, followed by a series of bioinformatics analysis on RNA-seq data, including de novo assembly, annotation, classification and metabolic pathway analysis of the assembled unigene. Meanwhile, a deep analysis on the steroidal saponin biosynthesis in secondary metabolism pathway was performed. The results showed a total of 126 546 unigene were obtained by de novo transcriptome assembly, of which 47 226 were annotated. Of these, 16 499 unigene were mapped to 132 specific pathways, of which 2 768 were identified to be involved in 22 secondary metabolic pathways. One hundred and thirteen unigene were identified from the transcriptome database, which encoded 27 metabolic enzymes associated with steroidal saponin biosynthesis and shared similarity with 45 functional genes in Arabidopsis thaliana. In conclusion, a series of candidate functional genes, which might be involved in steroidal saponin biosynthesis, were selected from the transcriptome database of P. cyrtonema rhizome. Further investigation of these candidate genes will provide insight into their actual functions in the steroidal saponin biosynthetic pathway in P. cyrtonema. In addition, this study also provide abunant reference data for transcriptome characterization of P. cyrtonema and has important significance for functional genomics of P. cyrtonema.

Keywords: Polygonatum cyrtonema; active components; secondary metabolism; steroidal sapogenin; transcriptome.