Floral Volatile Profiling of Dendrobium sinense at Different Flowering Stages and Its Correlation With Pollinators

To explore the dynamic variation of floral volatile organic compounds (VOCs) in Dendrobium sinense across different flowering stages and their interactions with pollinators, this study analyzed the composition and relative abundance of VOCs during bud, blooming, and aging stages. Floral VOCs were collected using headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry (HS-SPME-GC-MS). 22 VOCs from eight classes were identified, with esters and terpenoids as the dominant components. Total emissions showed a trend of first decreasing and then increasing from the bud stage to the aging stage. The richest diversity of floral volatile was detected at the blooming period of flower development. β-caryophyllene, α-pinene, benzyl acetate, cis-3-hexenyl acetate, methylheptenol, and benzyl alcohol dominated the floral VOCs of D. sinense across different flowering stages. Previous electrophysiological studies have shown that benzyl acetate and benzyl alcohol elicit strong antennal responses in Vespa bicolor, the primary pollinators of D. sinense, suggesting they may be key attractants. Additionally, cis-3-hexenyl acetate and nonanal are also considered to contribute to the pollination process. This study reveals the temporal release patterns of floral VOCs in D. sinense, identifies key semiochemicals, and aids in understanding obligate pollination while guiding conservation of endangered plants.