Emission of volatile organic compounds in Mediterranean fig trees bearing receptive flowers: dynamics under diurnal temperature light conditions

Cao, Li

FRONTIERS IN ECOLOGY AND EVOLUTION

2026

14

Cao, L; Proffit, M

Floral scents are formed by a complex mixture of Volatile Organic Compounds (VOCs) which play major roles in mediating encounter with partners in plant-pollinator interactions. Hence, VOC temporal patterns may be regulated to respond to both pollinator's activity and pollination status. In the nursery pollination mutualism between the dioecious fig tree, Ficus carica, and its exclusive pollinator the fig wasp, Blastophaga psenes, it has been reported that VOCs emitted by receptive figs mediate species-specific interaction and that a combination of four VOCs - benzyl alcohol, (S)-linalool, (Z)-linalool oxide (furanoid) and (E)-linalool oxide (furanoid) - are responsible for pollinator attraction. However, the temporal pattern of their emissions during the day has never been studied. Previous studies on floral scents have mostly relied on offline collection methods that provide only discrete snapshots of emission rates. To bridge this gap and capture the continuous 'pulse' of floral signaling, we employed real-time Proton-Transfer-Reaction Time-of-Flight Mass Spectrometry (PTR-TOF-MS). This high-resolution approach allows us to characterize, for the first time, the fine-scale diurnal kinetics of VOC emissions in the F. carica nursery pollination system and to assess how these signals withstand natural environmental fluctuations. In addition, we estimated the influence of light intensity and temperature on these emissions under semi-natural conditions, based on simultaneous measurements and statistical modeling. Emissions of VOCs from flowering trees followed a diurnal pattern with a peak at midday, corresponding to the period when the pollinator is most active, with very conserved proportions of VOCs attractive to pollinators around this peak. Our results indicate that VOC emissions exhibited a diurnal rhythm closely associated with the natural fluctuation of temperature and light. While the conditions used in our studies did not allow us to disentangle the effects of these two factors, our analyses suggest nonlinear relationships between these factors and the emissions of compounds attractive to pollinators. Further experimental studies are needed on F. carica, as well as on other species, to better assess how light intensity and temperature drive floral VOC emissions.