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Oriental hybrid lily flowers have a pleasant fragrance. Especially in a confined space, however, the scent can be perceived as too strong and therefore unpleasant. Our analysis of the major scent compounds in cut flowers of 'Casa Blanca' lilies, which is one of the most popular oriental hybrid lilies in Japan, identified two aromatics (benzyl alcohol and iso-eugenol) and two terpenoids (linalool and cis-ocimene). In addition, p-creosol (aromatics) was detected as a minor component. Based on sensual impressions, we assumed that iso-eugenol and p-creosol were the main causes of the unpleasant odor. We concluded that inhibitors of the biosynthesis of aromatics could decrease concentrations of these compounds and make the fragrance of 'Casa Blanca' less unpleasant. The biosynthesis of aromatics is generally catalyzed by phenylalanine ammonia-lyase (PAL). We used aminooxy acetic acid (AOA) and L-2-aminooxy-3-phenylpropionoic acid (AOPP) as PAL inhibitors. Application of AOA and AOPP at 0.1 mM and 1.0 mM by vase treatment decreased the emissions of scent compounds. For practical application, AOA was selected because of its much lower cost. Continuous treatment with AOA decreased the emissions of scent compounds to 10 to 20% of the control at a constant ratio at all times of day on the second and third days after flowering when 'Casa Blanca' emitted the greatest amounts of scent compounds. Similar effects were found on the last day of flowering. Under certain conditions, temporary treatment for 24 h evoked similar effects as continuous treatment. Application of 1.0 mM AOA caused chemical injury to the tepals, but 0.1 mM AOA did not. Treatment of plants with opened flowers was less effective than treatment at a late bud stage. In summary, continuous post-harvest treatment with 0.1 mM AOA of 'Casa Blanca' at late flower bud stages can decrease the emissions of scent compounds and render the fragrance milder without affecting flower morphology through its period of use as an ornamental.

• Background and Aims Among the subspecies of Petunia axillaris are various lines emitting sensorially different scents. Analysis of variations in floral scent among genetically close individuals is a powerful approach to understanding the mechanisms for generating scent diversity.• Methods Emitted and endogenous components were analysed independently to gain information about evaporation and endogenous production in 13 wild lines of P. axillaris. A dynamic headspace method was used to collect emitted components. Endogenous components were extracted with solvent. Both of these sample types were subjected to quantitative and qualitative analysis by gas chromatography (GC)–flame ionization detector (FID) and GC–mass spectrometry (MS).• Key Results and Conclusions Whereas the profiles of emitted compounds showed qualitative homogeneity, being mainly composed of methyl benzoate with quantitative variation, the profiles of endogenous compounds showed both qualitative and quantitative variation. A negative correlation was found between the evaporation ratio and boiling point of each compound examined. Lower boiling point compounds were strongly represented in the emitted component, resulting in the reduction of qualitative variation in floral scent. In conclusion, floral scent diversity results from variation in both the endogenous production and the evaporation rate of the individual volatile compounds.

We investigated the effect of overexpressing a pumpkin gibberellin (GA) 20-oxidase gene encoding an enzyme that forms predominantly biologically inactive products on GA biosynthesis and plant morphology in transgenic lettuce (Lactuca sativa cv Vanguard) plants. Lettuce was transformed with the pumpkin GA 20-oxidase gene downstream of a strong constitutive promoter cassette (El2-35S-⍀). The transgenic plants in which the pumpkin gene was detected by polymerase chain reaction were dwarfed in the T 2 generation, whereas transformants with a normal growth phenotype did not contain the transgene. The result of Southern-blot analysis showed that the transgene was integrated as a single copy; the plants segregated three dwarfs to one normal in the T 2 generation, indicating that the transgene was stable and dominant. The endogenous levels of GA 1 and GA 4 were reduced in the dwarfs, whereas large amounts of GA 17 and GA 25 , which are inactive products of the pumpkin GA 20-oxidase, accumulated in these lines. These results indicate that a functional pumpkin GA 20-oxidase is expressed in the transgenic lettuce, resulting in a diversion of the normal pathway of GA biosynthesis to inactive products. Furthermore, this technique may be useful for controlling plant stature in other agricultural and horticultural species.