Abstract: In recent years, persistently elevated concentrations of atmospheric ozone (O₃) have not only reduced plant productivity but also interfered with compound metabolism, leading to distortion of chemical signals, disruption of local ecological balance, and threats to the precision of symbiotic interactions between animals and plants, as well as to ecosystem service functions. This study investigated the impact of elevated ozone concentrations on plant chemical signaling and stomatal adaptation by comparing the volatile odor composition of receptive syconia and leaf stomatal characteristics of Ficus hispida in natural sites with high and low ozone concentrations in Guangzhou City. Using gas chromatography–mass spectrometry (GC-MS) analysis, a total of 43 volatile organic compounds (VOCs) were identified across both sites, with 32 compounds common to both. Terpenoids dominated the profile. Furthermore, the high-ozone site exhibited specific oxidized products such as Decanal, Sesquicineole, and Caryophyllene oxide. Non-metric multidimensional scaling (NMDS) analysis revealed significant spatial differentiation in VOC composition between the two sites (Stress < 0.2). Permutational multivariate analysis of variance (PERMANOVA) identified significant differences (P < 0.05) in the proportional composition of 12 shared compounds (Germacrene D, α-Amorphene, α-Humulene, (E)-β-Farnesene, α-trans-Bergamotene, (E)-Caryophyllene, β-elemene, β-Cubebene, trans-Linalool oxide, (E)-β-Ocimene, Indole, Hex-(3Z)-enyl acetate) between the sites. This indicates a significant alteration in plant volatile chemical signaling between natural sites with high and low ozone concentrations, potentially reflecting plant responses to ambient atmospheric conditions (e.g., rising ozone levels) or underlying adaptive strategies. Meanwhile, in the high-ozone plots, the stomatal length and area of Ficus hispida leaves significantly decreased, along with a reduction in chlorophyll content. This study reveals the changes in volatile chemical signals and stomatal physiological characteristics of Ficus hispida under natural high-ozone conditions, providing new evidence for understanding how ozone pollution may potentially disrupt plant-pollinator interaction networks by affecting interspecies chemical communication and plant stomatal features.

Key words: Ozone, Ficus hispida, Receptive syconia, Volatile organic compounds, Stomata