Exploratory Correlation of De Novo Transcriptome Data and GC-MS Volatile Essential Oils Profile of W. salutaris...

Warburgia salutaris, a medicinal plant native to southern Africa, is renowned for its essential oil, which is rich in monoterpenes and sesquiterpenes with therapeutic properties. This study explores the correlation between de novo transcriptome data and the volatile essential oil profile of W. salutaris leaves to elucidate the gene-metabolite relationships involved in secondary metabolite biosynthesis. Essential oil was extracted from fresh leaves using hydrodistillation and analysed via gas chromatography-mass spectrometry (GC-MS), identifying 34 volatile compounds, including monoterpenes and sesquiterpenes. To explore the genetic pathways of terpene biosynthesis, a transcriptome was generated using RNA sequencing, yielding over 79 million raw reads, with 60% usable data. The assembly produced 55,687 transcripts, of which 68,004 were coding sequences. Functional annotation through the Kyoto Encyclopedia of Genes and Genomes (KEGG) database identified genes encoding mono- and sesquiterpene synthases. However, not all metabolites in the essential oil were represented by corresponding genes, as some terpenes act as precursors. Nine of the 34 identified compounds were directly or indirectly linked to transcriptome data. This first comparative study of W. salutaris essential oil and de novo transcriptome data provides valuable insights into the interplay between gene transcription and metabolite production, highlighting the complexity of plant metabolism.