Identification and Verification of BAHDs Related to Benzyl Acetate Synthesis in Prunus mume

Prunus mume as the only plant in the genus Prunus of the Rosaceae family possesses a characteristic floral scent. Benzyl acetate is the most significant component of the floral scent in P. mume. However, the potential volatilization and synthesis mechanism of benzyl acetate has not been elucidated clearly. Here, 5 flower parts (petal, filament, anther, calyx and pistil + flower disc) of P. mume ‘Caizhiwufen’ were used to evaluated the volatile and endogenous components using GC-MS. The results showed that benzyl acetate mainly originated from petals and anthers according to its endogenous content. Based on the genomic data from P. mume, 94 BAHDs were identified and clustered into five major Groups. Moreover, the expression patterns of 94 BAHD genes in different flower organs and WGCNA analysis demonstrated that PmBAHD25 in brown module was highly expressed in petals, which was positively correlated to the synthesis of benzyl acetate in petals. Furthermore, compared with the wild-type plants, the length of fruit pods was much smaller, and the surface of fruit pods was wrinkled and deformed in the transgenic PmBAHD25 Arabidopsis thaliana plants. Additionally, the substrate catalysis showed that the overexpression PmBAHD16 in A. thaliana plants could specifically catalyze benzyl alcohol into benzyl acetate, while PmBAHD25 exhibited a wide range selectivity of substrates. Our findings demonstrated that the PmBAHDs play an important role in promoting the production of benzyl acetate in P. mume.