Integrating GC-MS and comparative transcriptome analysis reveals that TsERF66 promotes the biosynthesis of caryophyllene in Toona sinensis tender leaves

The strong aromatic characteristics of the tender leaves of determine their quality and economic value. Here, GC-MS analysis revealed that caryophyllene is a key volatile compound in the tender leaves of two different varieties, however, the transcriptional mechanisms controlling its gene expression are unknown. Comparative transcriptome analysis revealed significant enrichment of terpenoid synthesis pathway genes, suggesting that the regulation of terpenoid synthesis-related gene expression is an important factor leading to differences in aroma between the two varieties. Further analysis of expression levels and genetic evolution revealed that is a caryophyllene synthase, which was confirmed by transient overexpression in and leaves. Furthermore, we screened an AP2/ERF transcriptional factor ERF-IX member, , for the potential regulation of caryophyllene synthesis. The had a similar expression trend to that of and was highly expressed in high-aroma varieties and tender leaves. Exogenous spraying of MeJA also induced the expression of and and promoted the biosynthesis of caryophyllene. Transient overexpression of in T. sinensis significantly promoted expression and caryophyllene biosynthesis. Our results showed that promoted the expression of and the biosynthesis of caryophyllene in leaves, providing a strategy for improving the aroma of tender leaves.