Wax Layers onCosmos bipinnatusPetals Contribute Unequally to Total Petal Water Resistance

Abstract

V6T 1Z1 (R.J.) Cuticular waxes coat all primary aboveground plant organs as a crucial adaptation to life on land. Accordingly, the properties of waxes have been studied in much detail, albeit with a strong focus on leaf and fruit waxes. Flowers have life histories and functions largely different from those of other organs, and it remains to be seen whether flower waxes have compositions and physiological properties differing from those on other organs. This work provides a detailed characterization of the petal waxes, using Cosmos bipinnatus as a model, and compares them with leaf and stem waxes. The abaxial petal surface is relatively flat, whereas the adaxial side consists of conical epidermis cells, rendering it approximately 3.8 times larger than the projected petal area. The petal wax was found to contain unusually high concentrations of C 22 and C 24 fatty acids and primary alcohols, much shorter than those in leaf and stem waxes. Detailed analyses revealed distinct differences between waxes on the adaxial and abaxial petal sides and between epicuticular and intracuticular waxes. Transpiration resistances equaled 3 3 10 4 and 1.5 3 10 4 s m 21 for the adaxial and abaxial surfaces, respectively. Petal surfaces of C. bipinnatus thus impose relatively weak water transport barriers compared with typical leaf cuticles. Approximately two-thirds of the abaxial surface water barrier was found to reside in the epicuticular wax layer of the petal and only one-third in the intracuticular wax. Altogether, the flower waxes of this species had properties greatly differing from those on vegetative organs.

Compositae Plants Differed in Leaf Cuticular Waxes between High and Low Altitudes

“…Short-chain length (mainly C 20 -C 24 ) for fatty acids and primary alcohols was expected to result in a larger volume for water transit surrounding the crystalline domains and relatively high permeability [52]. Our results on the primary alcohols and fatty acids confirmed this conclusion.…”

Floral Humidity in Flowering Plants: A Preliminary Survey

“…Differences in petal permeability between species could also lead to variation in floral humidity production. Transpirational water loss can occur directly through the petal cuticle (Patiño and Grace, 2002;Buschhaus et al, 2015;Guo et al, 2017). Petals often have more permeable cuticles than leaves, allowing greater water loss (von Arx et al, 2012;Buschhaus et al, 2015).…”

“…Transpirational water loss can occur directly through the petal cuticle (Patiño and Grace, 2002;Buschhaus et al, 2015;Guo et al, 2017). Petals often have more permeable cuticles than leaves, allowing greater water loss (von Arx et al, 2012;Buschhaus et al, 2015). Variation in the rate of transpirational water loss can be due to differences in the chemical composition of the cuticle (Corbet et al, 1979b;Schreiber and Riederer, 1996;Goodwin et al, 2003;Guo et al, 2017) and cuticle thickness (Hajibagheri et al, 1983).…”

Chemical Composition of the Cuticle Membrane of Pitaya Fruits (Hylocereus Polyrhizus)

“…In the present study, the weighted ACL of aliphatic compounds, which were calculated based on the molar concentration of VLCFAs, were 30.5 in pitaya fruit cuticle ( Table 1). The ACL loading has been reported in the cuticle of a variety of plant species and/or different fruits [11,13,14], leaves [13,21,24], and petals [24,30] reported previously as comparison groups. ACL of aliphates in pitaya fruit cuticle was similar to the median value in leaf waxes, and higher than that in most of the fruit and petal cuticular waxes previously reported ( Figure 6).…”