title: Chemical and structural analysis of Eucalyptus globulus and E. camaldulensis leaf cuticles: a lipidized cell wall region.
abstract: The plant cuticle has traditionally been conceived as an independent hydrophobic layer that covers the external epidermal cell wall. Due to its complexity, the existing relationship between cuticle chemical composition and ultra-structure remains unclear to date. This study aimed to examine the link between chemical composition and structure of isolated, adaxial leaf cuticles of Eucalyptus camaldulensis and E. globulus by the gradual extraction and identification of lipid constituents (cutin and soluble lipids), coupled to spectroscopic and microscopic analyses. The soluble compounds and cutin monomers identified could not be assigned to a concrete internal cuticle ultra-structure. After cutin depolymerization, a cellulose network resembling the cell wall was observed, with different structural patterns in the regions ascribed to the cuticle proper and cuticular layer, respectively. Our results suggest that the current cuticle model should be revised, stressing the presence and major role of cell wall polysaccharides. It is concluded that the cuticle may be interpreted as a modified cell wall region which contains additional lipids. The major heterogeneity of the plant cuticle makes it difficult to establish a direct link between cuticle chemistry and structure with the existing methodologies.
authors.affiliation: Forest Genetics and Ecophysiology Research Group, School of Forest Engineering, Technical University of Madrid Madrid, Spain.
authors.forename: Paula
authors.initials: P
authors.lastname: Guzmán
authors.affiliation: Forest Genetics and Ecophysiology Research Group, School of Forest Engineering, Technical University of Madrid Madrid, Spain.
authors.forename: Victoria
authors.initials: V
authors.lastname: Fernández
authors.affiliation: Instituto Superior de Agronomia, Centro de Estudos Florestais, Universidade de Lisboa Lisboa, Portugal.
authors.forename: José
authors.initials: J
authors.lastname: Graça
authors.affiliation: Instituto Superior de Agronomia, Centro de Estudos Florestais, Universidade de Lisboa Lisboa, Portugal.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Cabral
authors.affiliation: Mass Spectrometry Unit, Faculty of Chemistry, University Complutense of Madrid Madrid, Spain.
authors.forename: Nour
authors.initials: N
authors.lastname: Kayali
authors.affiliation: Department of Applied Physics I, Faculty of Physics, University Complutense of Madrid Madrid, Spain.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Khayet
authors.affiliation: Forest Genetics and Ecophysiology Research Group, School of Forest Engineering, Technical University of Madrid Madrid, Spain.
authors.forename: Luis
authors.initials: L
authors.lastname: Gil
keywords: cell wall; cuticle; cutin; eucalypt; leaf; lipids; polysaccharides; ultra-structure