Atomic force microscopy study of isolated ivy leaf cuticles observed directly and after embedding in Epon®.

Abstract

The first results obtained by atomic force microscopy (AFM) of the fine structure of isolated ivy leaf cuticles are reported. Observations of transverse sections embedded in Epon® allow easy recognition of the general shape of cuticles as viewed by light microscopy. The surface profile shows irregularities not revealed by transmission electron microscopy (TEM). The lamellate and reticulate zones, distinguishable by TEM, were also located by AFM. The outer zone appears as an irregularly thick (c. 4 μm) homogeneous region; lamellae can be visualized only after image-processing to subtract relief defects produced by sectioning. The second region or internal zone represents the largest part of the cuticle thickness; it appears heterogeneous and disordered. The cuticle internal surface images show imprints of the epidermal cells. At high magnification, the cell imprint central regions appear to be made up of a network of fibres of c. 50 nm diameter. Some images show that these fibres have a preferential orientation. They disappear after acid-hydrolysis is used to eliminate polysaccharides. This study shows that AFM can produce reproducible images of isolated plant cuticles at a subcellular scale leading to new high-resolution representations of cuticle substructure.