Combined analysis of transcriptomics and metabolomics revealed complex metabolic genes for diterpenoids biosynthesis in different organs of Anoectochilus roxburghii

OBJECTIVE: Diterpenoids with a wide variety of biological activities from Anoectochilus roxburghii, a precious medicinal plant, are important active components. However, due to the lack of genetic information on the metabolic process of diterpenoids in A. roxburghii, the genes involved in the molecular regulation mechanism of diterpenoid metabolism are still unclear. This study revealed the complex metabolic genes for diterpenoids biosynthesis in different organs of A. roxburghii by combining analysis of transcriptomics and metabolomics. METHODS: The differences in diterpenoid accumulation in roots, stems and leaves of A. roxburghii were analyzed by metabonomic analysis, and its metabolic gene information was obtained by transcriptome sequencing. Then, the molecular mechanism of differential diterpenoid accumulation in different organs of A. roxburghii was analyzed from the perspective of gene expression patterns. RESULTS: A total of 296 terpenoid metabolites were identified in the five terpenoid metabolic pathways in A. roxburghii. There were 38, 34, and 18 diterpenoids with different contents between roots and leaves, between leaves and stems, and between roots and stems, respectively. Twenty-nine metabolic enzyme genes with 883 unigenes in the diterpenoid synthesis process were identified, and the DXS and FDPS in the terpenoid backbone biosynthesis stage and CPA, GA20ox, GA3ox, GA2ox, and MAS in the diterpenoid biosynthesis stage were predicted to be the key metabolic enzymes for the accumulation of diterpenoids. In addition, 14 key transcription factor coding genes were predicted to be involved in the regulation of the diterpenoid biosynthesis. The expression of genes such as GA2ox, MAS, CPA, GA20ox and GA3ox might be activated by some of the 14 transcription factors. The transcription factor NTF-Y and PRE6 were predicted to be the most important transcription factors. CONCLUSION: This study determined 29 metabolic enzyme genes and predicted 14 transcription factors involved in the molecular regulation mechanism of diterpenoid metabolism in A. roxburghii, which provided a reference for the further study of the molecular regulation mechanism of the accumulation of diterpenoids in different organs of A. roxburghii.