Abstract Ultrastructural observation of the rhizosphere requires preservation of spatial continuity across heterogeneous biological and mineral components. Although correlative imaging approaches integrate electron microscopy with chemical and isotopic analyses, maintaining large-area structural integrity in intact plant–microbe–soil composites remains technically demanding. Here, we show that biological cross-sectional polishing scanning electron microscopy enables centimeter-scale cross-sectional observation of resin-embedded soil interfaces while retaining subcellular ultrastructural detail. The workflow combines conventional fixation used for plant electron microscopy with low-viscosity resin embedding, diamond band-saw sectioning, and mechanical polishing to generate flat cross sections suitable for backscattered electron imaging using standard scanning electron microscopes. Application to laboratory-grown and field-collected samples revealed microbial aggregates, biofilm-like matrices, fungal networks, and diverse soil-associated organisms observed within preserved spatial relationships. Although this method does not provide chemical or lineage-specific identification, it establishes a reproducible structural framework that complements multiscale imaging and supports targeted downstream analyses in complex environmental systems.
Toyooka et al. (2026) studied this question.