Analysis of volatile organic compound diversity revealed the differentiation of scent traits and candidate genes for sweet-aroma formation rose petals

Roses exhibit significant potential as important ornamental plants and industrial crops with petals having high volatile organic compound (VOC) content, diverse aromatic profiles, and pleasant fragrance. The fragrance traits of petals, especially the sweet-aroma, are closely related to the evaluation of petal-derived products, and the development of novel cultivars. However, the scent diversity and key regulatory gene expression among different germplasms remain unclear. In this study, the petal VOC profiles of 32 rose varieties were analyzed. A total of 80 VOCs were detected, and the total VOC content ranged from 6.16 ± 0.03 to 28.26 ± 0.18 μg·g−1 FW, with an average of 13.80 μg·g−1 FW. Monoterpenoids and benzenoids/phenylpropanoids accounted for 93.53% of the total VOC content. Based on the content and odor activity value of each compound, geraniol, citronellol, β-phenylethanol, and linalool were identified as key characteristic components. The scents of all 32 germplasms were classified into five categories: floral-geranium, floral-green rose, floral-sweet rose, floral-lily, and floral-mixed. β-Phenylethanol and linalool were regarded as the target compounds for the characteristic sweet-aroma in floral-sweet rose and floral-lily scented germplasms. Gene expression analysis suggested that RrNUDX1-1a, RrCAD1, RrTPS1, RrAAAT1, and RrPAR2 were related to the differentiation of petal fragrances. Transient overexpression and silencing expression experiments verified that RrTPS1, RrAAAT1, and RrPAR2 regulated the biosynthesis of β-phenylethanol and linalool, emerging as potential targets for breeding sweet-scented cultivars. These findings explored the diversity of VOC in rose, providing both theoretical foundations and gene resources for rose floral characteristics improvement and novel cultivar development.