Expansion of genes in the genome induces characteristic floral scent production.

is the only plant in the genus of the Rosaceae family with a characteristic floral scent, and the main component of this scent is benzyl acetate. By contrast, benzyl acetate is not synthesized in flowers. Here, we searched for () genes based on genomic data from and and found 44 unique in . These genes, which were mainly detected in clusters on chromosomes, originated from gene duplication events during the species evolution of , and retroduplication and tandem duplication were the two dominant duplication patterns. The genes , and , which were generated by tandem duplication, were highly expressed in flowers, and their highest levels were detected during the blooming stage. In vitro, PmBEAT34, PmBEAT3, and PmBEAT37 all had benzyl alcohol acetyltransferase activity that was localized in the cytoplasm. Overexpression of the or genes increased benzyl acetate production in the petal protoplasts of , and interference in the expression of these genes slightly decreased the benzyl acetate content. In addition, light and temperature regulated the expression of the , and genes. According to these results, we hypothesize that the expansion of the genes in the genome induce the characteristic floral scent of .