Cuticle characteristics and volatile emissions of petals in Antirrhinum majus

Abstract

Floral volatiles, which are small and generally water-insoluble, must move from their intracellular sites of synthesis through the outermost cuticle membrane before release from the flower surface. To determine whether petal cuticle might influence volatile emissions, we performed the first analysis of petal cuticle development and its association with the emission of flower volatiles using Antirrhinum majus L. (snapdragon) as a model system. Petal cuticular wax amount and composition, cuticle thickness and ultrastructure, and the amounts of internal and emitted methylbenzoate (the major snapdragon floral scent compound) were examined during 12 days, from flower opening to senescence. Normal (n-) alkanes were found to be the major wax class of snapdragon petals (29.0% to 34.3%) throughout the 12 days examined. Besides n-alkanes, snapdragon petals possessed significant amounts of methyl branched alkanes (23.6-27.8%) and hydroxy esters (12.0-14.0%). Hydroxy esters have not been previously reported in plants. Changes in amount of methylbenzoate inside the petals followed closely with levels of methylbenzoate emission, suggesting that snapdragon petal cuticle may provide little diffusive resistance to volatile emissions. Moreover, clear associations did not exist between methylbenzoate emission and the cuticle properties examined during development. Nevertheless, the unique wax composition of snapdragon petal cuticles shows similarities with those of other highly permeable cuticles, suggesting an adaptation that could permit rapid volatile emission by scented flowers.

Wax Layers onCosmos bipinnatusPetals Contribute Unequally to Total Petal Water Resistance

“…*, C 25 alkane quantities were calculated based on relative amounts of alkane homologs determined separately after TLC. C 34 range of waxes on vegetative organs , whereas the petal wax chain lengths are reminiscent of those in flower waxes from diverse other species (Hennig et al, 1988;Griffiths et al, 2000;Goodwin et al, 2003, King et al, 2007.…”

“…Petals must also resist unfavorable environmental conditions such as a desiccating atmosphere. Some characteristics that increase reproductive success, including their high surface areas and surface permeability to small scent molecules, may also make petals more vulnerable to drying out (Goodwin et al, 2003;Bergougnoux et al, 2007). Thus, despite their ephemeral nature, petals may need to compromise between competing physiological and ecological functions.…”

“…Noteworthy exceptions are detailed analyses of petal waxes for Crataegus monogyna and three cultivars of Rubus idaeus (Griffiths et al, 2000), Antirrhinum majus (Goodwin et al, 2003), Vicia faba (Griffiths et al, 1999), Cistus albidus (Hennig et al, 1988), Petunia hybrida (King et al, 2007), Arabidopsis (Arabidopsis thaliana; Shi et al, 2011), and Rosa damascena (Stoianova-Ivanova et al, 1971). Selected compound classes have been investigated for some more species, including selected Ericaceae (Salasoo, 1989), Rosaceae (Wollrab, 1969a(Wollrab, , 1969b, and Asteraceae (Akihisa et al, 1998) species.…”

Floral humidity as a reliable sensory cue for profitability assessment by nectar-foraging hawkmoths

“…Cuticular permeability to water is influenced by physicochemical properties. For example, the cuticle of snapdragon flowers (Antirrhinum majus; Plantaginaceae) is dominated by branched alkanes and hydroxy esters (25), which provide a less effective diffusion barrier than long-chain wax hydrocarbons lacking branches, double bonds, and functional groups (26)(27)(28). Furthermore, increased transpiration rates have been shown to be associated with reduced cuticular thickness (29).…”

Cloning and Expression of cDNAs for Biosynthesis of Very-long-chain Fatty Acids, the Precursors for Cuticular Wax Formation, in Carnation (Dianthus caryophyllus L.) Petals

“…The actual components are hydrocarbons (alkanes) in a high proportion among total components, followed by monoesters of long-chain alcohols and fatty acids, and very-long-chain alcohols (mainly C 22 -C 34 ) and verylong-chain saturated fatty acids (Harwood, 1997). For instance, in snapdragon, the major components of petal wax are n-alkanes (29.0-34.3%), followed by methylbranched alkanes (23.6-27.8%) and hydroxyl esters (12.0-14.0%) (Goodwin et al, 2003).…”