Functional identification of PmABCGs in floral scent transport of Prunus mume

Prunus mume, the only plant in the genus Prunus of the Rosaceae family with a distinctive floral scent, can release a large number of aromatic substances into the air when it blooms. Among these, benzyl acetate has been recognized as a characteristic aromatic substance. In this study, we extracted and analyzed the change in volatility and endogenous content of benzyl acetate using the 'Caizhiwufen' P. mume flowers. The volatile compounds of the paraxial abaxial surfaces and inner and outer petals were detected by gas chromatography-mass spectrometry (GC-MS). We analyzed the expression patterns of the ABCG subfamily, compared the volatilization efficiencies in spatial and temporal differences, and hypothesized PmABCG2, 9, 11, and 16 that were associated with the transmembrane transport of benzyl acetate. We then cloned the above candidate genes, constructed the pTRV2-PmABCGs gene silencing vectors, and transiently infiltrated P. mume via vacuum infiltration. The volatile amount of benzyl acetate was significantly decreased, and endogenous content was higher than that of the control, which preliminarily verified that PmABCG9 could transport benzyl acetate. Finally, we incubated tobacco plants with exogenous benzyl acetate, benzyl alcohol, and leaf acetate and found that PmABCG9 specifically selected benzyl acetate as a substrate. The results of this study could support the hypothesis that PmABCG9 could effectively promote the volatilization of benzyl acetate and elucidate the transmembrane transport mechanism of benzyl acetate in P. mume.