Transport properties of cuticular waxes of Fagus sylvatica L. and Picea abies (L.) Karst.: Estimation of size selectivity and tortuosity from diffusion coefficients of aliphatic molecules

Schreiber, Lukas; Kirsch, Thomas; Riederer, Markus

doi:10.1007/bf00197592

Cited by 37 publications

(22 citation statements)

References 28 publications

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“…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).…”

Section: Discussionmentioning

confidence: 99%

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

Arx

Goyret

Davidowitz

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

118

148

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Most research on plant-pollinator communication has focused on sensory and behavioral responses to relatively static cues. Floral rewards such as nectar, however, are dynamic, and foraging animals will increase their energetic profit if they can make use of floral cues that more accurately indicate nectar availability. Here we document such a cue-transient humidity gradients-using the night blooming flowers of Oenothera cespitosa (Onagraceae). The headspace of newly opened flowers reaches levels of about 4% above ambient relative humidity due to additive evapotranspirational water loss through petals and water-saturated air from the nectar tube. Floral humidity plumes differ from ambient levels only during the first 30 min after anthesis (before nectar is depleted in wild populations), whereas other floral traits (scent, shape, and color) persist for 12-24 h. Manipulative experiments indicated that floral humidity gradients are mechanistically linked to nectar volume and therefore contain information about energy rewards to floral visitors. Behavioral assays with Hyles lineata (Sphingidae) and artificial flowers with appropriate humidity gradients suggest that these hawkmoth pollinators distinguish between subtle differences in relative humidity when other floral cues are held constant. Moths consistently approached and probed flowers with elevated humidity over those with ambient humidity levels. Because floral humidity gradients are largely produced by the evaporation of nectar itself, they represent condition-informative cues that facilitate remote sensing of floral profitability by discriminating foragers. In a xeric environment, this level of honest communication should be adaptive when plant reproductive success is pollinator limited, due to intense competition for the attention of a specialized pollinator.pollination biology | honest signaling | floral display P lant-pollinator relationships-like all mutualisms-strike a tenuous balance between the conflicting interests of foraging animals and flowering plants (1, 2). For flowering plants, pollinator attraction through floral density, form, color, pattern, and odor is necessary but insufficient to ensure effective pollination. Ideally, pollinators should transfer pollen between conspecific plants in ways that result in favorable levels of outcrossing (3) and reduced pollen loss (4). Flowers commonly manipulate pollinator movement by varying quality or quantity of floral nectar. The offer of variable amounts of nectar (5, 6), toxic nectar (7, 8), or an empty promise of nectar elicit similar results: pollinators leave plants sooner, reducing for example geitonogamous inbreeding (if selfcompatible) or pollen discounting (if self-incompatible).The availability of floral rewards often coincides with floral display and pollinator activity on a gross temporal scale (i.e., hours) (9, 10). Nevertheless, most pollinators encounter rewardless ("empty") flowers on a finer temporal scale (i.e., minutes), often due to recent visitation by another animal. From the pollin...

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Section: Discussionmentioning

confidence: 99%

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

Arx

Goyret

Davidowitz

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

118

148

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“…Aliphatic model compounds were excluded, as their k* 0 values diered from those obtained with cyclic compounds Schreiber et al 1996).…”

Section: Methodsmentioning

confidence: 99%

Differences among plant species in cuticular permeabilities and solute mobilities are not caused by differential size selectivities

Buchholz

Baur

Schönherr

1998

Planta

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Solute mobilities in cuticular membranes of six species (Hedera helix, Malus domestica, Populus alba, Pyrus communis, Stephanotis¯oribunda, Strophantus gratus) were measured using plant hormones, growth regulators and other organic model compounds varying in molar volumes from 99 to 349 mL á mol A1 The dependence of mobilities (k*) on molar volume (V x ) was exponential and could be described with equations of the type log k* log k* 0 À b H x . The y-intercepts log k* 0 represent mobilities of a hypothetical solute of zero molar volume. The parameter b¢ is a measure of size selectivity of cuticular membranes and no dierences among the six species were observed. At 25°C the average b¢ was 0.0095 mol á mL A1 . Solute mobility decreased by about a factor of 8.9 when molar volume increased by 100 mL á mol A1 and the mobility of a compound with V x 100 mL á mol A1 was about 700-fold higher than the mobility of a compound with V x 400 mL á mol A1 . Size selectivity decreased with increasing temperatures and for Strophantus b¢-values of 1.6´10 A2 to 8.0´10 -4 mol á mL A1 were obtained for 10 and 30°C, respectively. The-intercepts (log k* 0 ) diered among plant species by 3 orders of magnitude and since size selectivity was the same for all species, solute mobilities for solutes having zero molar volumes were the sole cause for dierences among species in solute mobilities and permeabilities. We argue that these dierences in k* 0 are related to tortuosity of the diusion path. These results were used to derive an equation which predicts rates of cuticular penetration on the basis of k* 0 , the average size selectivity of 9.5´10 A3 mol á mL A1 and the driving forces of penetration.

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“…These results for total stem wax match previous reports on the Col ecotype (Pighin et al, 2004), and are dramatically higher than the wax load of 0.75 mg/cm 2 on leaves (data not shown). The distribution of waxes on the surface of various stem segments is not likely to be influenced by diffusional transport within the cuticle because, clearly, the polyester components are not mobile and diffusion coefficients measured for fatty acids and alkanes in reconstituted cuticular waxes (Schreiber et al, 1996) imply that lateral wax diffusion will be a very slow process, less than 0.01 mm/d.…”

Section: Deposition Of Waxesmentioning

confidence: 99%

Cuticular Lipid Composition, Surface Structure, and Gene Expression in Arabidopsis Stem Epidermis

et al. 2005

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All vascular plants are protected from the environment by a cuticle, a lipophilic layer synthesized by epidermal cells and composed of a cutin polymer matrix and waxes. The mechanism by which epidermal cells accumulate and assemble cuticle components in rapidly expanding organs is largely unknown. We have begun to address this question by analyzing the lipid compositional variance, the surface micromorphology, and the transcriptome of epidermal cells in elongating Arabidopsis (Arabidopsis thaliana) stems. The rate of cell elongation is maximal near the apical meristem and decreases steeply toward the middle of the stem, where it is 10 times slower. During and after this elongation, the cuticular wax load and composition remain remarkably constant (32 mg/cm 2 ), indicating that the biosynthetic flux into waxes is closely matched to surface area expansion. By contrast, the load of polyester monomers per unit surface area decreases more than 2-fold from the upper (8 mg/cm 2 ) to the lower (3 mg/cm 2 ) portion of the stem, although the compositional variance is minor. To aid identification of proteins involved in the biosynthesis of waxes and cutin, we have isolated epidermal peels from Arabidopsis stems and determined transcript profiles in both rapidly expanding and nonexpanding cells. This transcriptome analysis was validated by the correct classification of known epidermis-specific genes. The 15% transcripts preferentially expressed in the epidermis were enriched in genes encoding proteins predicted to be membrane associated and involved in lipid metabolism. An analysis of the lipid-related subset is presented.

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Transport properties of cuticular waxes of Fagus sylvatica L. and Picea abies (L.) Karst.: Estimation of size selectivity and tortuosity from diffusion coefficients of aliphatic molecules

Cited by 37 publications

References 28 publications

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

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

Differences among plant species in cuticular permeabilities and solute mobilities are not caused by differential size selectivities

Cuticular Lipid Composition, Surface Structure, and Gene Expression in Arabidopsis Stem Epidermis

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