Integrated Transcriptomic and Metabolomic Profiling Provides Molecular Insights into Volatile and Nonvolatile Metabolite Dynamics during Flower Development in Chinese Jujube and Sour Jujube

Chinese
jujube and sour jujube flowers are recognized
for their
distinct fragrance and nutritional benefits. However, the currently
reported classes of metabolites in these flowers remain relatively
scarce, and their underlying molecular regulation remains unclear.
Using gas chromatography–mass spectrometry and ultrahigh-performance
liquid chromatography-electrospray ionization-tandem mass spectrometry,
369 volatile metabolites and 1840 nonvolatile metabolites were identified.
Compared to Chinese jujube flowers, sour jujube flowers showed greater
relative levels of the majority of differently accumulated metabolites.
Ester and terpenoid compounds were the primary volatile differentially
accumulated metabolites, whereas flavonoids constituted the dominant
nonvolatile differentially accumulated metabolites. ZjMYB86 expression was negatively correlated with the late flavonoid structural
genes. Functional overexpression studies demonstrated that ZjMYB86 inhibited anthocyanin accumulation. The ZjMYB86-overexpressing line showed downregulation of most
anthocyanin metabolites and of the late biosynthetic gene ZjBZ1 compared to the control. Overall, these results enhanced
understanding of the chemical profiles and metabolite distribution
patterns in jujube flowers.