Analysis of transcriptome of Dioscorea zingiberensis and excavation of key enzyme genes of saponin biosynthesis / 中草药

ABSTRACT

Objective To compare and analyze the transcriptome of rhizome and leaves of Dioscorea zingiberensis, and excavate the key enzyme genes related to the saponin biosynthetic pathway in D. zingiberensis. Methods The transcriptome of rhizome and leaves of D. zingiberensis were sequenced by Illumina HiSeq2000 high-throughput sequencing technique. According to sequence annotate results to find the differentially expressed genes. Then the key enzyme genes related to the biosynthesis of diosgenin were identified according to the content of saponins in rhizomes and leaves of D. zingiberensis. The expression levels of some candidate genes were analyzed by real-time fluorescence quantitative PCR (qRT-PCR). Results A total of 81 660 Unigenes were gained and 64.33% of them were annotated in NT, NR, Swiss-Prot, KOG, GO, and KEGG databases. Based on their expression and KEGG annotation, totally 227 catalytic enzyme genes of 29 kinds that may participate in D. zingiberensis saponin biosynthetic pathway were screened. The expression pattern of some catalytic enzymes was correlated with the content of saponin. Also were found five D. zingiberensis endophyte genes. Conclusion This experiment obtained candidate key enzyme genes tentatively that involved in the biosynthesis of saponin. Some candidate enzyme genes may participate in the post-modification process of steroidal saponins in D. zingiberensis. In additon, it was found that D. zingiberensis endotrophic bacteria may be involved in the saponin biosynthesis. The results laid a foundation to further elucidate the molecular mechanism of sapogenin synthesis pathway.