Identification of floral aromatic volatile compounds in 29 cultivars from four groups of Osmanthus fragrans by gas chromatography-mass spectrometry

Osmanthus fragrans Lour. is a popular aromatic ornamental plant and its flowers are used to enhance the color and fragrance of food. In this study, we analyzed the volatiles of 29 cultivars from all four groups of O. fragrans using a solid-phase microextraction (SPME) technique and gas chromatography-mass spectrometry (GC-MS). We identified 41 volatile organic components that were distributed over five different compound classes, with the majority of the volatile components being dominated by alcohols, ketones, and terpenes, which accounted for 56.6-95.06% of the total volatiles in all tested materials except Zao Yingui'. In Zao Yingui', alcohols, ketones, and terpenes accounted for only 48.19% of the total volatiles. The diversity of the volatile compounds and their relative contents varied among the four groups and cultivars within each group. The major volatile compounds were alpha-ionone, beta-ionone, 2H-beta-ionone, linalool, trans-linalool oxide, cis-linalool oxide, epoxy linalool, geraniol (Z)-ocimene, and gamma-decalactone in all tested cultivars, while nerol and (Z)-3-hexenyl butanoic acid ester were abundant in several cultivars. The 29 cultivars were classified into five clusters in a hierarchical cluster analysis based on their floral volatile compounds. The cultivars of different sexes (male vs. hermaphrodite) had no significant differences in the relative contents of the major volatile compounds. This study provides valuable information for understanding the chemical composition of the volatile compounds of O. fragrans flowers as well as a theoretical basis for the origin, development, and application of modern cultivars of O. fragrans.