Transcriptomic and metabolomic data reveal key genes that are involved in the phenylpropanoid pathway and regulate the floral fragrance of Rhododendron fortunei

• Published in: BMC plant biology Vol. 23; no. 1; pp. 8 - 23
• Main Authors: Yang, Guoxia, Qin, Yi, Jia, Yonghong, Xie, Xiaohong, Li, Dongbin, Jiang, Baoxin, Wang, Qu, Feng, Siyu, Wu, Yueyan
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 05-01-2023; BioMed Central; BMC
• Subjects: Analysis; Benzene; Benzenes/phenylpropanoids; Floral aroma; Gene Expression Profiling; Gene Expression Regulation, Plant; Genes; Genetic research; Metabolites; Metabolome; Metabolome and transcriptome analyses; Odorants; Phenylpropanoid biosynthesis pathway; Propionates - metabolism; Rhododendron; Rhododendron - genetics; Salicylic acid carboxyl methyl transferase; Transcriptome; China; Salicylic acid carboxyl methyl transferase; Phenylpropanoid biosynthesis pathway; Metabolome and transcriptome analyses; Floral aroma; Benzenes/phenylpropanoids; Rhododendron
• ISSN: 1471-2229; 1471-2229
• DOI: 10.1186/s12870-022-04016-7

To reveal the key genes involved in the phenylpropanoid pathway, which ultimately governs the fragrance of Rhododendron fortunei, we performed a comprehensive transcriptome and metabolomic analysis of the petals of two different varieties of two alpine rhododendrons: the scented R. fortunei and the unscented Rhododendron 'Nova Zembla'.
Our transcriptomic and qRT-PCR data showed that nine candidate genes were highly expressed in R. fortunei but were downregulated in Rhododendron 'Nova Zembla'. Among these genes, EGS expression was significantly positively correlated with various volatile benzene/phenylpropanoid compounds and significantly negatively correlated with the contents of various nonvolatile compounds, whereas CCoAOMT, PAL, C4H, and BALDH expression was significantly negatively correlated with the contents of various volatile benzene/phenylpropanoid compounds and significantly positively correlated with the contents of various nonvolatile compounds. CCR, CAD, 4CL, and SAMT expression was significantly negatively correlated with the contents of various benzene/phenylpropanoid compounds. The validation of RfSAMT showed that the RfSAMT gene regulates the synthesis of aromatic metabolites in R. fortunei.
The findings of this study indicated that key candidate genes and metabolites involved in the phenylpropanoid biosynthesis pathway may govern the fragrance of R. fortunei. This lays a foundation for further research on the molecular mechanism underlying fragrance in the genus Rhododendron.