Comparative transcriptome analysis of MeJA-responsive AP2/ERF transcription factors involved in notoginsenosides...

Differential transcriptome analysis is an effective method for gene selection of triterpene saponin biosynthetic pathways. MeJA-induced differential transcriptome of Panax notoginseng has not been analyzed yet. In this study, comparative transcriptome analysis of P. notoginseng roots and methyl jasmonate (MeJA)-induced roots revealed 83,532 assembled unigenes and 21,947 differentially expressed unigenes. Sixteen AP2/ERF transcription factors, which were significantly induced by MeJA treatment in the root of P. notoginseng, were selected for further analysis. Real-time quantitative PCR (RT-qPCR) and co-expression network analysis of the 16 AP2/ERF transcription factors showed that PnERF2 and PnERF3 had significant correlation with dammarenediol II synthase gene (DS) and squalene epoxidase gene (SE), which are key genes in notoginsenoside biosynthesis, in different tissues and MeJA-induced roots. A phylogenetic tree was conducted to analyze the 16 candidate AP2/ERF transcription factors and other 38 transcription factors. The phylogenetic tree analysis showed PnERF2, AtERF3, AtERF7, TcERF12 and other seven transcriptional factors are in same branch, while PnERF3 had close evolutionary relationships with AtDREB1A, GhERF38 and TcAP2. The results of comparative transcriptomes and AP2/ERF transcriptional factors analysis laid a solid foundation for further investigations of disease resistance and notoginsenoside biosynthesis in P. notoginseng.