De novo transcriptome sequencing and metabolite profiling analyses reveal the complex metabolic genes involved in the terpenoid biosynthesis in Blue Anise Sage (Salvia guaranitica L.)

Many terpenoid compounds have been extracted from different tissues of Salvia guaranitica. However, the molecular genetic basis of terpene biosynthesis pathways is virtually unknown. In this study, approximately 4 Gb of raw data were generated from the transcriptome of S. guaranitica leaves using Illumina HiSeq 2000 sequencing. After filtering and removing the adapter sequences from the raw data, the number of reads reached 32 million, comprising 186 million of high-quality nucleotide bases. A total of 61,400 unigenes were assembled de novo and annotated for establishing a valid database for studying terpenoid biosynthesis. We identified 267 unigenes that are putatively involved in terpenoid metabolism (including, 198 mevalonate and methyl-erythritol phosphate (MEP) pathways, terpenoid backbone biosynthesis genes and 69 terpene synthases genes). Moreover, three terpene synthase genes were studied for their functions in terpenoid biosynthesis by using transgenic Arabidopsis; most transgenic Arabidopsis plants expressing these terpene synthetic genes produced increased amounts of terpenoids compared with wild-type control. The combined data analyses from the transcriptome and metabolome provide new insights into our understanding of the complex metabolic genes in terpenoid-rich blue anise sage, and our study paves the way for the future metabolic engineering of the biosynthesis of useful terpene compounds in S. guaranitica.