A few hours of flowering
An Epiphyllum oxypetalum flower opens at night, and a mixture of volatile compounds accumulates in the surrounding air. Zhang and colleagues followed this process in plants cultivated in Sichuan. Whole flowers remained attached to the plant during scent collection. Air passed through a system that trapped compounds for subsequent identification by gas chromatography and mass spectrometry. [Zhang et al. 2025, pp.1–3,11]
After 20 h local time, emission increased approximately 200-fold within six hours. Geraniol, benzyl alcohol and methyl salicylate followed different release patterns. Total emission peaked in the open flower. Subsequent wilting was accompanied by changes in the amounts and proportions of compound classes. [Zhang et al. 2025, pp.1–3,Fig.1]
Scent-producing tissues
At peak emission, geraniol accounted for 72.54% of the released volatile compounds. Benzyl alcohol and methyl salicylate predominated among the remaining components. The authors analysed petals, sepals, the floral tube, stamens and pistil separately. Petals and sepals were the main scent sources. Organ profiles changed between the prebloom, full-bloom and postbloom stages. [Zhang et al. 2025, pp.1–4,Fig.2]
This comparison resolves whole-flower scent into processes occurring in individual parts. Sampling the air surrounding a living flower measures emission. Analysis of sampled organs helps identify tissues that produce and release compounds. Combining these methods links chemical composition to developmental stage. [Zhang et al. 2025, pp.2–4,10–11]
The enzyme and the mevalonate pathway
Geraniol is a monoterpene produced from geranyl diphosphate. In the studied cactus, the authors identified synthase EoTPSa1. RNA analysis revealed a marked increase in its expression during flowering. In enzyme assays, the purified protein produced geraniol from the supplied substrate. This experiment directly confirmed the function of the encoded enzyme. [Zhang et al. 2025, pp.4–10,12]
Protein localization was examined by transient expression in Nicotiana benthamiana leaves and confocal microscopy. The result indicated the cytosol. Metabolic pathway inhibitors supported the involvement of the mevalonate pathway in precursor supply. The authors thus linked emission to protein activity and the cellular source of biosynthetic material. [Zhang et al. 2025, pp.4–10,11–12]
Biological significance
Nocturnal scent is a temporally organized floral chemical signal. The 2025 study explains its production in detail in the analysed material. Scent composition and timing provide a basis for further experiments on pollinator behaviour. Biochemical analysis characterizes flower metabolism, whereas attraction effectiveness requires observations of visits and pollen transfer. [Zhang et al. 2025, pp.8–10,Discussion]
Geraniol synthase also provides a starting point for biotechnological research on fragrance production. The authors identify this possible application. Enzyme characterization supplies a mechanistic basis, while development of a production process would require further investigation of yield and biosynthetic conditions. [Zhang et al. 2025, pp.10]
Based on the full text of an original research study.
Floral scent emission of Epiphyllum oxypetalum: discovery of its cytosol-localized geraniol biosynthesis
Zhang Y., Zhang Y., Zhang A., Tian Q., Yang B., Wei L., Wu W., Zhu T., Zhou Z., Wang J., Liu Z., Tang W., Xiao H., Liu M., Li T., Sun Q., Floral scent emission of Epiphyllum oxypetalum: discovery of its cytosol-localized geraniol biosynthesis, Horticulture Research, 2025, 12(5):uhaf039, doi: 10.1093/hr/uhaf039
Biochemistry of scent emission and cytosolic geraniol synthesis in Epiphyllum oxypetalum.