High-resolution imaging and in situ cutting of leaf epicuticular waxes of the biomass plant Miscanthus sinensis

The leaf surface features of the biomass plant Miscanthus sinensis were investigated by electron and ion beam microscopy. Fully developed leaves were collected from the plant, air-dried and examined by field emission scanning electron microscopy. Stomata and longitudinal stripes were present on both the adaxial and abaxial leaf surfaces. Longitudinally aggregated rodlets surrounded the stomata and formed hollow cylinders or chimney-like structures. With varying lengths up to ∼10 μm, the rodlets were curved (<1 μm in diameter) and almost occluded the stomata. As another type of epicuticular wax, platelets were observed in the vicinity of the stomata. The platelets were arranged into rather radially assembled clusters. As a novel approach for cross sectioning native epicuticular waxes, focused ion beam milling allowed precise in situ cutting of the stomata and epicuticular waxes. The longitudinally aggregated rodlets of the stomatal chimneys of M. sinensis were derived from the stomatal guard cells. These results suggest that the epicuticular waxes of M. sinensis can be categorized as stomatal chimneys (Strelitzia type) and rosettes (Fabales type). Combined electron and ion beam microscopy can help unravel the ultrastructure and vertical profile of epicuticular waxes in a range of plant taxa.