High‐resolution episcopic microscopy enables three‐dimensional visualization of plant morphology and development

Abstract

The study of plant anatomy, which can be traced back to the seventeenth century, advanced hand in hand with light microscopy technology and relies on traditional histologic techniques, which are based on serial two‐dimensional (2D) sections. However, these valuable techniques lack spatial arrangement of the tissue and hence provide only partial information. A new technique of whole‐mount three‐dimensional (3D) imaging termed high‐resolution episcopic microscopy (HREM) can overcome this obstacle and generate a 3D model of the specimen at a near‐histological resolution. Here, we describe the application of HREM technique in plants by analyzing two plant developmental processes in woody plants: oil secretory cavity development in citrus fruit and adventitious root formation in persimmon rootstock cuttings. HREM 3D models of citrus fruit peel showed that oil cavities were initiated schizogenously during the early stages of fruitlet development. Citrus secretory cavity formation, shape, volume, and distribution were analyzed, and new insights are presented. HREM 3D model comparison of persimmon rootstock clones, which differ in their rooting ability, revealed that difficult‐to‐root clones failed to develop adventitious roots due to their inability to initiate root primordia.

Review of Existing Methods for Evaluating Adhesive Bonds in Timber Products

“…Light microscopy can be used in generating 2 and 3D images of structures. 3D imaging of a sample's volume can be achieved by further processing of either microtome sectioning and stacking of images using visualisation software or using optical techniques (such as light-sheet microscopy, confocal laser scanning microscopy or optical projection tomography) to mount the images taken into volumetric models [27][28][29]. Florescence microscopy is used to separate wood cells from the glue line [30] using short wavelength light to brighten sections of the sample [24].…”

“…The images are then stacked using visualisation software to develop a 3D model of the sample block. A florescence stereomicroscope and a digital camera are used to capture the dye mixture embedded in the sample block in visualising the structural components [29]. The HREM method has been successfully used in various medical applications providing better resolution imaging in comparison with X-ray computed tomography, MRI, and optical projection tomography (OPT) [28,38].…”

“…The HREM method has been successfully used in various medical applications providing better resolution imaging in comparison with X-ray computed tomography, MRI, and optical projection tomography (OPT) [28,38]. Samples require detailed processing of dehydrated tissues prior to HREM imaging using 4% paraformaldehyde (w/v) for 1-2 hours under vacuum and then incubated at 4°C overnight before being washed by ethanol and embedded in embedding solution (Figure 10) [29].…”

Light and Light Signals Regulate Growth and Development in Woody Plants

“…Beyond its bioenergetic role, photic exposure exerts a direct influence on morphological development, governing the leaf movements and density of branching, the morphology and anatomy of foliage, and the chronobiology of anthesis. Diverse photic parameters, including spectral composition, photon flux density, and photoperiodicity, intersect to form a delicate and precise regulatory matrix [11,12].…”