Rehydration of dried mushroom specimens with Aerosol® OT for scanning electron microscopy

Morphological, anatomical and ultrastructural characteristics are important for taxonomical and phylogenetic studies of fungi. For scanning electron microscopy (SEM), usually only dry voucher specimens are available. For dried plant material, Aerosol® OT (AOT) has been shown to be a suitable rehydration agent for SEM preparation. For swelling and stabilization of fungal cells, however, this simple method does not yield satisfactory results. Here, we show that a combination of AOT with ultrasonic bath and rehydration in a vacuum desiccator is a good method to distend fungal cells like basidiospores and pleuro- and cheilocystidia for SEM analysis. Tissues of several species of Agaricomycetes with diverse morphological structures were exposed to the treatment. Diverse concentrations of AOT as well as treatments in an ultrasonic bath and a vacuum desiccator were tested to optimize the surface reconstruction and to reduce preparation artefacts. The evaluated rehydration method is a cheap, quick and nontoxic method to prepare dried specimens of fungal cells for SEM analysis.