Transcriptome analysis of Akebia quinata (Thunb.) Decne. and discovery of key enzyme genes in the phenylpropanoid biosynthesis pathway

Akebia quinata is a dry vine stem of Akebia quinata (Thunb.) Decne. in the Lardizabalaceae Akebia Decne, which has antibacterial, anti-tumor, and diuretic properties. Calceolarioside B is a known effective component of Akebia quinata . Moreover, calceolarioside B is a phenylpropanoid, the current understanding of the molecular mechanisms of phenylpropanoid biosynthetic pathway is not clear. In this study, we performed RNA-Seq analysis of the flowers, leaves, roots, and stems of Akebia quinata using the BGISEQ-500 platform. The assembly of transcripts from all four types of tissues generated 123,576 unigenes, of which 90,273 were mapped to several public databases for functional annotation. We identified 182 genes encoding 13 key enzymes involved in phenylpropanoid biosynthesis through their KEGG annotation. DEGs were identified via the comparison of gene expression levels between stems and other tissues (flowers, leaves, and roots). We also verified the expression levels of some unigenes encoding key enzymes using qRT-PCR. This analysis of the phenylpropanoid biosynthesis pathway and its crucial enzymes in Akebia quinata lays a foundation for uncovering the regulatory mechanism of phenylpropanoid biosynthesis. The expression patterns of genes involved in the phenylpropanoid biosynthesis pathway were verified using qRT-PCR. We suggest that transcripts of 4CL may be key regulators in the phenylpropanoid biosynthetic pathway. Our results greatly extend the public transcriptome data set of Akebia quinata and provide valuable information for the identification of candidate genes involved in phenylpropanoid biosynthesis.