Topp Lab

Xray microscopy (XRM)

Overview

To extend our imaging capabilities, we added a ZEISS Xradia 520 Versa X-ray microscope (XRM) in April 2018, supported by our research collaboration with Valent BioSciences, Sumitomo Chemical Company, and the Donald Danforth Plant Science Center.
This is currently the only lab-based XRM in the world dedicated exclusively to studying plant science, and our February 2022 publication in Plant Physiology (Duncan et al., 2022) describes how we have used XRM for a wide range of economically important plant species.

How it works

The XRM is a powerful and versatile instrument for generating detailed 3D volume data of delicate and complicated samples. The multiscale capability allows high magnification region-of-interest scans to be situated within the context of lower magnification scans of entire samples, without removing the sample from the instrument. The animations and screen shots below illustrate both the range of plant and soil samples that we have studied as well as the multiscale capability of the instrument. We’re also using XRM to study arbuscular mycorrhizal fungi (AMF) and their interaction with roots in situ. We developed various strategies for generating contrast of AMF structures for in vitro and in situ visualization of hyphae, spores, arbuscules, and vesicles.

Root-microbe colonization

Roots of Brachypodium colonized by Rhizophagus irregularis, contrasted with osmium and imaged by XRM in situ.

Carrot root AMF

In vitro carrot root cultures colonized by R. irregularis, contrasted with osmium tetroxide.

Carrot root AMF

In vitro carrot root cultures colonized by R. irregularis, contrasted with Wheat Germ Agglutinin conjugated to 40nm gold particles.

Soil aggregate

Multiscale overlaid scans of soil aggregate, part of a project to use X-ray imaging to evaluate pore space from soils under differing management strategies.

Pennycress pod

Low magnification scan of a pennycress pod with overlaid high magnification scan of two developing seeds, with individual cell layers and developing cotyledons visible.

Arabidopsis flower

Multiscale overlaid scans of Arabidopsis flower with long slender ovary containing multiple ovules, surrounded by pollen-filled anthers.

Soil aggregate

Multiscale overlaid scans of soybean flower with ovary containing three ovules, surrounded by pollen-containing anthers. Polar nuclei and synergids are visible in the high magnification scan of a single ovule.

Soybean ovule

Fly-through animation of 2D digital slices through a developing soybean ovule, showing rich cell-level detail.

Soybean nodule

Multiscale overlaid scans of soybean nodule formed by the nitrogen-fixing bacterium Bradyrhizobium japonicum. Host vascular bundles are evident surrounding the nodule, and the hundreds of bacteroids with bright nuclei are visible.