Integrative Analysis of the Transcriptome and Metabolome Reveals the Developmental Mechanisms and Metabolite Biosynthesis of the Tuberous Roots of Tetrastigma hemsleyanum.

The tuberous root of Tetrastigma hemsleyanum Diels et Gilg (T. hemsleyanum) is a traditional Chinese medicine with a wide range of clinical applications. However, the scarcity of its wild resources, its low yield, and the variable quality that results from its artificial cultivation leads to expensive market prices that are not conducive to the further industrial development of T. hemsleyanum. In this study, transcriptomic and non-targeted metabolomic analyses were integrated to explore the underlying molecular mechanisms and metabolite biosynthesis that occur during its root development. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that differentially expressed genes (DEGs) were predominantly enriched for processes associated with flavonoid and phenylpropanoid biosynthesis, starch and sucrose metabolism, and plant hormone signal transduction. Genes related to lignin were downregulated in tuberous roots (TRs), resulting in a decrease in lignification and the downregulation of metabolites related to flavonoids and phenylpropanoid biosynthesis. In addition, the expression levels of starch- and sucrose-related genes were upregulated in TRs. The root development of SYQ is also related to IAA, GA, ABA, and JA signaling pathways. Collectively, this study lays the foundation for analyzing the root development and quality-modulating mechanisms employed by T. hemsleyanum; this will be beneficial in conducting molecular-assisted breeding and controlling its secondary metabolite production.