Structural and functional imaging of large and opaque plant specimens

Abstract

Three- and four-dimensional imaging techniques are a prerequisite for spatially resolving the form–structure–function relationships in plants. However, choosing the right imaging method is a difficult and time-consuming process as the imaging principles, advantages and limitations, as well as the appropriate fields of application first need to be compared. The present study aims to provide an overview of three imaging methods that allow for imaging opaque, large and thick (>5 mm, up to several centimeters), hierarchically organized plant samples that can have complex geometries. We compare light microscopy of serial thin sections followed by 3D reconstruction (LMTS3D) as an optical imaging technique, micro-computed tomography (µ-CT) based on ionizing radiation, and magnetic resonance imaging (MRI) which uses the natural magnetic properties of a sample for image acquisition. We discuss the most important imaging principles, advantages, and limitations, and suggest fields of application for each imaging technique (LMTS, µ-CT, and MRI) with regard to static (at a given time; 3D) and dynamic (at different time points; quasi 4D) structural and functional plant imaging.

4D pine scale: biomimetic 4D printed autonomous scale and flap structures capable of multi-phase movement

“…It is a very promising prospect for future biological studies to investigate the interrelation of scale architecture (cellular characteristics at different regions) in combination with the scale biomechanics (e.g. by AFM measurements) and the locally successive evaporation of water (probably via MRI) [48,49], altogether leading to the observed multi-phase motion. Our analyses show the potential of full-field 3D displacement and deformation analyses for evaluation and validation of movement principles in plants and technical structures.…”

Plant biomechanics in the 21st century

“…Finally, a necessary complement to mechanical testing is the investigation of the 3D structure of specimens, and recent technical developments enable this to be done in a non-invasive manner. Hesse et al (2019) compare different imaging methods targeted at large and opaque plant specimens for which, until recently, the only way to visualize the inner structure was destructive.…”

Complexity untwined: The structure and function of cucumber (Cucumis sativus L.) shoot phloem

“…The most common techniques used to study vascular networks are those based on reconstructions from serial sections, procedures that are laborious and often compromised by the distortions that invariably occur as sections are obtained and processed. A number of more tractable imaging methods are now available that enable structural analysis in three dimensions (Hesse et al ., 2019). Among these, X‐ray computed tomography (CT), is widely used for clinical and research imaging.…”