Leaf cuticular waxes are arranged in chemically and mechanically distinct layers: evidence from Prunus laurocerasus L.

Abstract

The composition and spatial arrangement of cuticular waxes on the leaves of Prunus laurocerasus were investigated. In the wax mixture, the triterpenoids ursolic acid and oleanolic acid as well as alkanes, fatty acids, aldehydes, primary alcohols and alcohol acetates were identified. The surface extraction of upper and lower leaf surfaces yielded 280 mg m -2 and 830 mg m -2, respectively. Protocols for the mechanical removal of waxes from the outermost layers of the cuticle were devised and evaluated. With the most selective of these methods, 130 mg m -2 of cuticular waxes could be removed from the adaxial surface before a sharp, physically resistant boundary was reached. Compounds thus obtained are interpreted as 'epicuticular waxes' with respect to their localization in a distinct layer on the surface of the cutin matrix. The epicuticular wax film can be transferred onto glass and visualized by scanning electron microscopy. Prunus laurocerasus epicuticular waxes consisted entirely of aliphatic compounds, whereas the remaining intracuticular waxes comprised 63% of triterpenoids. The ecological relevance of this layered structure for recognition by phytotrophic fungi and herbivorous insects that probe the surface composition for sign stimuli is discussed.

Wax Layers onCosmos bipinnatusPetals Contribute Unequally to Total Petal Water Resistance

“…Interestingly, the wax on immature leaves of Prunus laurocerasus was also dominated by C 24 fatty acid, alcohol, and acetate, similar to C. bipinnatus petal waxes, whereas mature P. laurocerasus leaves contained mainly the C 28 to C 32 acids and alcohols plus C 29 /C 31 alkanes typical of leaves in other species (Jetter et al, 2000;Jetter and Schäffer, 2001). This comparison illustrates that, even though mature organs may have very different wax mixtures, they may still go through developmental stages with very similar compositions.…”

OSC2 and CYP716A14v2 Catalyze the Biosynthesis of Triterpenoids for the Cuticle of Aerial Organs of Artemisia annua

“…The cuticle covers the aerial surfaces of plant organs by forming a hydrophobic layer that acts as a physical barrier to protect the plant from biotic and abiotic stresses. The cuticle is composed of two main components, cutin and wax (Jetter et al, 2000). Triterpenoids are the biologically active constituents of the wax layer (Buschhaus and Jetter, 2011;Szakiel et al, 2012).…”

Les cires végétales : sources et applications

“…Cette diversité va dépendre de très nombreux facteurs comprenant le type de cire (épi-ou intracuticulaire), la partie de la plante considé-rée (feuille, tige, fruit…), l'espèce végétale, l'age, la saison ou encore les conditions agro-climatiques. Ainsi, les cires de feuilles de Prunus laurocerasus seront exclusivement aliphatiques s'il s'agit de la fraction épicuticulaire alors que les triterpénoïdes seront les constituants principaux (63 %) de la fraction intracuticulaire [15]. Par ailleurs, les cires épicuticulaires de feuilles peuvent avoir une composition radicalement différente suivant si elles proviennent de la face abaxiale ou adaxiale, comme cela a pu être observé dans le cas du pois [10] (71 % d'alcools primaires pour la face adaxiale contre 73 % d'alcanes pour l'abaxiale).…”