Atomic force microscopy for direct imaging and nanoscale morphometry of the rice false smut fungus Ustilaginoidea virens

Atomic force microscopy (AFM) was used for direct imaging and nanoscale morphometry of spined conidia of Ustilaginoidea virens. Basic components of AFM include a piezoscanner, a cantilever and a photodiode for surface scanning and image formation. Topographic imaging by AFM exhibited surface topographic images of 'untreated' conidia at the comparable spatial resolution with conventional scanning electron microscopy. Numerical analysis of the surface parameters over 1.0 × 1.0 μm² scan areas revealed a variety of mean height (239.5 ± 124.7 nm), root-mean-squared roughness (78.2 ± 31.8 nm), surface area (1.8 ± 0.6 μm²), and volume (239.6 ± 124.7 nm³) from acquired topographic images. These results suggest that AFM imaging and surface analysis can provide insights into a comprehensive understanding of fungal spores at the nanoscale level, opening a new venue in plant pathology and its related research areas.