Geranyl diphosphate synthase small subunit I (GPPS.SSU I) expression strongly correlates with the presence or absence of monoterpene emission from lily (Lilium spp.) flowers.

We reported the functional characterization of cDNAs encoding geranyl diphosphate synthase small subunit I (GPPS.SUU I) that determine the presence or absence of monoterpene emission from lily flowers. While monoterpene compounds are among the most important scent substances in lily flowers, their emission levels vary among lily cultivars.

Metabolome profiling of floral scent production in Petunia axillaris.

Emission of floral scent benzenoid/phenylpropanoid compounds in Petunia axillaris increases significantly at night, a change that is primarily determined by the endogenous concentration of these compounds in the corolla. Among wild type P. axillaris plants, there are lines that emit different amounts of scent.

Effect of temperature on the floral scent emission and endogenous volatile profile of Petunia axillaris.

The floral scent emission and endogenous level of its components in Petunia axillaris under different conditions (20, 25, 30, and 35 degrees C) were investigated under the hypothesis that floral scent emission would be regulated by both metabolic and vaporization processes. The total endogenous amount of scent components decreased as the temperature increased, the total emission showing a peak at 30 degrees C. This decrease in endogenous amount was compensated for by increased vaporization, resulting in an increase of floral scent emission from 20 degrees C to 30 degrees C.

Metabolic regulation of floral scent in Petunia axillaris lines: biosynthetic relationship between dihydroconiferyl acetate and iso-eugenol.

Aromatic scent-related compounds in flowers were comprehensively analyzed by high-performance liquid chromatography (HPLC) based on their absorption spectra to understand regulation of metabolism leading to floral scent diversity in Petunia axillaris lines. An unknown compound occurring at similar levels to scent compounds in some plant lines was identified to be dihydroconiferyl acetate. Based on the structure, dihydroconiferyl acetate is likely to be a biosynthetically closely related compound to aromatic scent compounds, especially iso-eugenol.

Emission mechanism of floral scent in Petunia axillaris.

The mechanism of floral scent emission was studied in Petunia axillaris, a plant with a diurnal rhythm of scent output. The emission rate of each volatile compound oscillated in synchrony with its endogenous concentration, so that the intensity of the floral scent appeared to be determined by the endogenous concentrations. The composition of major volatiles in the flower tissue and the flower headspace showed characteristic differences.