Variation in leaf cutin content and chemical composition along one annual cycle in the Mediterranean Cork Oak (Quercus suber L.)

Abstract

Plant leaves have one important protection barrier made up by a cuticle that covers their external surface and builds up a continuous extracellular, mostly hydrophobic, membrane on the epidermis that provides protection from biotic or abiotic stresses, namely from climatic harsh conditions, e.g., by limiting water loss and in heat insulation [1,2]. The cuticle includes a polymeric cutin matrix and cuticular waxes, linked to the epidermal cell wall by polysaccharides, also considered part of the cuticle as a cutin–polysaccharide matrix. Cutin is a polyester formed predominantly by cross-linking through ester bonds of C16 and C18 hydroxy fatty acids and glycerol, while cuticular waxes comprise very long-chain fatty acids and derivatives, alcohols, and alkanes as well as terpenes, sterols, and aromatics, and are soluble in non-polar solvents [3–6]. Cuticular waxes are located in the cuticle within the cutin matrix as an intracuticular layer, and on the outer surface of the cutin as an epicuticular layer [3]. Some cuticles also contain a resistant aliphatic polymer that is not depolymerized by ester-bond hydrolysis, the cutan, that has only a small proportion of aromatic moieties [7,8].info:eu-repo/semantics/publishedVersio