Comparative metabolome and transcriptome revealed the CpODO1 transcription factor controlling the varied floral scent traits of three wintersweet cultivars

Abstract

Wintersweet (Chimonanthus praecox L.), a well-known fragrant flowering shrub, is extensively planted for ornamental purpose and production of floral essential oil. Although the tepal color of wintersweet varieties exhibits the most remarkable diversity, variations in the floral scent traits are also noticeable across different cultivars. In this study, the floral volatile organic compounds (VOCs) in three wintersweet cultivars, ‘Yanlingsuxin’, ‘Yuxiang’, and ‘Hongyun’ were detected via GC–MS coupled with OAV. The distinct floral aromas of the three cultivars were primarily attributed to benzyl alcohol (abundant in ‘Yuxiang’), linalool (abundant in ‘Yanlingsuxin’), (−)-γ-cadinene and eugenol (abundant in ‘Hongyun’). Integrated analyses of metabolome and transcriptome showed that an R2R3-MYB transcription factor, CpODO1, potentially have a crucial regulatory function in controlling the production of multiple aroma compounds. Overexpression of CpODO1 can enhance the production of benzyl alcohol in transgenic tobacco flowers. Analysis of DAP-seq data, EMSA and dual-luciferase assay revealed that CpODO1 predominantly regulate the expression of CpCYP71, a cytochrome P450 gene encoding a key enzyme in the production of benzyl alcohol, and the transcriptional regulation of CpODO1 is driven by CpEOBII. The identification of polymorphisms in the MYB binding cis-motifs of CpCYP71 and CpODO1 promoters revealed the regulatory mechanism underlying the varied synthesis of benzyl alcohol in three wintersweet cultivars. This study provides new anchor points for floral scent quality improvement breeding of wintersweet, and the profusion of wintersweet germplasm can serve as a material basis for developing various aroma products.