Anatomical analysis of turgescent and semi-dry resurrection plants: the effect of sample preparation on the sample, resolution, and image quality of X-ray micro-computed tomography (μCT).

Computer tomography has been used frequently for the 3-D visualization of plant anatomical traits but sample preparation has been widely neglected. Without any preparation smaller (i.e., up to 1 × 1 cm(2) ) turgescent or semi-dry plant samples (especially leaf samples) diminish the image quality of a scan due to gradual water loss and therefore constant movement. A suitable preparation for scans of turgescent and semi-dry plant samples with a high resolution μCT (<1-5 μm) has to be very thin, heat-resistant (up to 35°C), have a low attenuation coefficient, and should not alter the water content and structure of the sample. Several agents have been tested, but only a coating with vaseline conserved the water content of a plant sample efficiently. However, water molecules and vaseline both attenuate the X-ray beam, which decreases the image quality of scans of turgescent or semi-dry plant samples. Therefore, trade-offs between the spatial resolution, sample water content, sample size, and image quality have to be considered: larger samples have to be placed further away from the X-ray tube, which leads to a lower spatial resolution; water and preparation agents attenuate the X-ray beam, causing low-quality images which may be accompanied by motion artifacts compared to a scan of a dry sample, where no preparation is necessary.