Plant cuticle
A plant cuticle is a protecting film covering the epidermis of leaves, young shoots and other aerial plant organs without periderm. It consists of lipid and hydrocarbon polymers impregnated with wax, and is synthesized exclusively by the epidermal cells.
Description
The plant cuticle is a layer of lipid polymer impregnated with waxes that is present on the outer surfaces of the primary organs of all vascular land plants.
It is also present in the sporophyte generation of hornworts, and in both sporophyte and gametophyte generations of mosses The plant cuticle forms a coherent outer covering of the plant that can be isolated intact by treatment of plant tissue with enzymes such as pectinase and cellulase.
Composition
The cuticle is composed of an insoluble cuticular membrane impregnated by and covered with soluble waxes. Cutin, a polyester polymer composed of inter-esterified omega hydroxy acids which are cross-linked by ester and epoxide bonds, is the best-known structural component of the cuticular membrane. The cuticle can also contain a non-saponifiable hydrocarbon polymer known as Cutan.<ref "Tegelaar 1989">Tegelaar, EW, et al. (1989) Scope and limitations of several pyrolysis methods in the structural elucidation of a macromolecular plant constituent in the leaf cuticle of Agave americana L., Journal of Analytical and Applied Pyrolysis, 15, 29-54</ref> The cuticular membrane is impregnated with cuticular waxes and covered with epicuticular waxes, which are mixtures of hydrophobic aliphatic compounds, hydrocarbons with chain lengths typically in the range C16 to C36.
