Control of Floral Scent Emission by Inhibitors of Phenylalanine Ammonia-lyase in Cut Flower of Lilium cv. ‘Casa Blanca’

Abstract

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.

Cloning and characterization of a benzoic acid/salicylic acid carboxyl methyltransferase gene involved in floral scent production from lily (Lilium ‘Yelloween’)

“…Scent can also be a strategy for defense of plants, acting as signals responding to injure and harm (Gang, 2005). Moreover, floral scent has important commercial value and appeal, improving consumers' buying desire (Oyama-Okubo et al, 2011). For example, a survey of sweet pea (Lathyrus odoratus) showed that purchasers consider aroma to be more attractive than flower shape or color (Sexton et al, 2005).…”

Odor Components and the Control of Odor Development in Ornamental Cabbage

“…When grown outdoors, Narcissus tazetta is recognized by its pleasant scent, whereas the smell emitted by a bouquet of narcissuses, especially in confined spaces where volatiles accumulate, becomes highly unpleasant (Vainstein et al, 2001). For similar reasons, cut flowers of oriental hybrid lilies tend to be avoided in restaurants (Oyama-Okubo et al, 2011). The concentration of a particular compound in a mixture of volatiles has marked effects; for example, a high level of indole has a very unpleasant odor, reminiscent of fecal matter, but at high dilutions, it is perceived as floral and pleasant (Vainstein et al, 2001).…”

“…AOA is also known to decrease the odor of cut flowers of Lilium cv. 'Casa Blanca' (Oyama-Okubo et al, 2011). However, AOA increased dimethyl disulfide emission in 'Haresugata' after six days of treatment (Fig.…”

“…The concentrations applied corresponded to the recommendations of the manufacturers; in the case of AOA, we followed Oyama-Okubo et al (2011).…”

“…The trapped volatiles were analyzed by GC-MS (Agilent 5973; Agilent Technologies, Wilmington, DE, USA) coupled to a Thermal Desorption System 2 (TDS2; Gerstel Inc.) (Oyama-Okubo et al, 2011). The thermal desorption conditions were heating from 30°C to 250°C at 60°C·min…”