RNA-Seq analysis revealed the expression of terpenes in different parts of Chimonocalamus delicatus at different culm ages

Chimonocalamus is the only bamboo species known to secrete aromatic oils. The species is named after the distinctive aromatic oil found within the cavity of its bamboo stem. This study employed sensory analysis, headspace-gas chromatography-mass spectrometry (HS-SPME-GC-MS), and transcriptome sequencing to investigate the volatile component composition and formation mechanisms in Chimonocalamus delicatus, an endemic bamboo species of Yunnan Province. The bamboo samples analyzed included stems at different stem ages, as well as various parts. The aroma components of Chimonocalamus delicatus primarily consist of sesquiterpenes, including Humulene and Caryophyllene, which are terpenoid compounds. Principal component analysis (PCA) revealed significant differences in the volatile compounds across various stem ages and plant parts. This may constitute a key source of the characteristic aroma of Chimonocalamus delicatus at different stem ages and plant parts. Transcriptome analysis revealed that the aroma of Chimonocalamus delicatus was predominantly enriched in the secondary metabolite pathways, including the MVA and MEP pathways. The enzyme activities of key enzymes in its metabolic pathway were also determined. A comprehensive analysis of differential aroma metabolites and differentially expressed genes (DEGs) in Chimonocalamus delicatus led to the identification of key genes (DXR, FPS, TPS6, TPS7) involved in the regulation of aroma compound biosynthesis. In this study, the volatile components and regulatory network of Chimonocalamus delicatus essential oil were analyzed, which provided a solid theoretical basis for the development of bioactive compounds in Chimonocalamus delicatus. Overall design: In order to study the difference of aroma composition and gene expression in different culm ages and parts of Chimonocalamus delicatus, a bamboo species endemic to Yunnan, China, we studied the samples of Chimonocalamus delicatus. Differences in the expression of terpene genes in different culm ages and in different sites were assessed. We also used RNA-seq to investigate the molecular basis of terpenoid genes in different parts of Chimonocalamus delicatus at the transcriptional level.