Synchrotron XFM tomography for elucidating metals and metalloids in hyperaccumulator plants

Visualizing the endogenous distribution of elements within plant organs affords key insights in the regulation of trace elements in plants. Hyperaccumulators have extreme metal(loid) concentrations in their tissues, which make them useful models for studying metal(loid) homeostasis in plants. X-ray-based methods allow for the nondestructive analysis of most macro and trace elements with low limits of detection. However, observing the internal distributions of elements within plant organs still typically requires destructive sample preparation methods, including sectioning, for synchrotron X-ray fluorescence microscopy (XFM). X-ray fluorescence microscopy-computed tomography (XFM-CT) enables virtual sectioning of a sample thereby entirely avoiding artefacts arising from destructive sample preparation. The method can be used on frozen-hydrated samples, as such preserving life-like conditions. Absorption and Compton scattering maps obtained from synchrotron XFM-CT offer exquisite detail on structural features that can be used in concert with elemental data to interpret the results. In this article we introduce the technique and use it to reveal the internal distribution of hyperaccumulated elements in hyperaccumulator plant species. XFM-CT can be used to effectively probe the distribution of a range of different elements in plant tissues/organs, which has wide ranging applications across the plant sciences.

Automated summary

This article introduces a technique for visualizing the distribution of elements within plant organs. It allows for nondestructive analysis of elements and virtual sectioning of samples, avoiding the need for destructive sample preparation methods. The technique can reveal the internal distribution of elements in hyperaccumulator plant species and has wide-ranging applications in the plant sciences.