Poster
Plant surfaces have distinct physicochemical characteristics. For instance wetting varies from super hydrophobic surfaces such as on Lotus (Nelumbo nucifera) to super hydrophilic surfaces such as on Calathea zebrina (Koch 2008). The specific wetting properties depend thereby on the chemistry and on the structure of the plant surface, which is covered by a thin extracellular membrane, the cuticle. The plant cuticle consists of cutin, an insoluble polymer matrix, and soluble waxes. The waxes can be incorporated into the cutin matrix, called intracuticular waxes and deposited on the outside of the surface, called epicuticular waxes, which build diverse three dimensional nanostructures by self-assembly. The cuticle with its waxes builds an important barrier against pathogens like pathogenic fungi. Paradoxically it gives key signals for host recognition, too. The wettability and by that the availability of water are among others crucial factors for a successful infection. Here an in vitro test system based on the model of wheat (Triticum aestivum) leaves was developed. This biomimetic system was created by physical vapor deposition (PVD) of extracted epicuticular waxes on small glass plates. By this procedure the waxes can be recrystallized forming three dimensional nanostructures as found on native leave surfaces. The chemical composition of wheat wax was analyzed by gas chromatography. The morphology of native and recrystallized nanostructures was analyzed by SEM and wetting properties were investigated by goniometer. The recrystallization by PVD gives the opportunity to transfer the characteristic physicochemical properties of a plant surface to a technical surface. This in vitro test system can be used as artificial leave for infection studies with pathogenic fungi. Further this biomimetic system offers the opportunity to change single parameters to identify crucial factors for a successful germination of pathogenic fungi.
