Dynamics of floral volatile emission and transcriptional regulation during flowering in Malus 'Prairie Rose'.

Malus 'Praire Rose' (MPR) stands out for its unique rose-like appearance and floral scent (FS) with potential applications in the fragrance industry. Despite limited exploration at the molecular level, this study investigated the FSs production mechanism in MPR across four flower developmental stages using metabolomics and transcriptomics. Results revealed that the predominant FSs in MPR flowers were terpenoids (à-Ionone, trans-á-Ionone, geranylacetone, and alpha-farnesene, etc.) and phenolic compounds (phenylethyl alcohol, 2-(4-Methoxyphenyl)ethanol, etc.). The highest concentration and diversity of these compounds were observed during the S4 developmental stage. 34 key differentiators (VIP ≥ 1&P＜0.05) were identified, including linalool, geranylacetone, trans-á-Ionone, 2-ethyl-6-methyl-phenol, 2-(4-methoxyphenyl)ethanol and phenylethyl alcohol. Transcriptomic analysis pinpointed 16 genes and 25 transcription factors highly correlated with the six volatile organic compounds above. The hypothesis posits a heightened reliance on the MEP pathway for the terpene synthesis pathway, emphasizing phenylethyl alcohol as a pivotal compound for distinguishing crabapple species. An intriguing observation suggests a potential inconsistency between compound synthesis rates and volatilization in MPR. The findings above deepen our understanding of FS, providing valuable perspectives for future research in the aromatic breeding of crabapples.