TY - JOUR

T1 - Correlative Imaging of the Rhizosphere ─ A Multimethod Workflow for Targeted Mapping of Chemical Gradients

AU - Lippold, Eva

AU - Schlüter, Steffen

AU - Mueller, Carsten W.

AU - Höschen, Carmen

AU - Harrington, Gertraud

AU - Kilian, Rüdiger

AU - Gocke, Martina I.

AU - Lehndorff, Eva

AU - Mikutta, Robert

AU - Vetterlein, Doris

N1 - Funding Information: This project was carried out in the framework of the priority programme 2089 “Rhizosphere Spatiotemporal Organisation─A Key to Rhizosphere Functions” funded by DFG, German Research Foundation (Project Number 403801423). The authors gratefully acknowledge Louis Rees for the help with the development of the embedding procedure, as well as Sebastian R.G.A. Blaser for help with X-ray CT measurements, Bernd Apelt for help in the laboratory whenever it was needed, and Maxime Phalempin for help with the root-segmentation algorithm. Publisher Copyright: © 2023 The Authors. Published by American Chemical Society.

PY - 2023

Y1 - 2023

N2 - Examining in situ processes in the soil rhizosphere requires spatial information on physical and chemical properties under undisturbed conditions. We developed a correlative imaging workflow for targeted sampling of roots in their three-dimensional (3D) context and assessed the imprint of roots on chemical properties of the root-soil contact zone at micrometer to millimeter scale. Maize (Zea mays) was grown in 15N-labeled soil columns and pulse-labeled with 13CO2 to visualize the spatial distribution of carbon inputs and nitrogen uptake together with the redistribution of other elements. Soil columns were scanned by X-ray computed tomography (X-ray CT) at low resolution (45 μm) to enable image-guided subsampling of specific root segments. Resin-embedded subsamples were then analyzed by X-ray CT at high resolution (10 μm) for their 3D structure and chemical gradients around roots using micro-X-ray fluorescence spectroscopy (μXRF), nanoscale secondary ion mass spectrometry (NanoSIMS), and laser-ablation isotope ratio mass spectrometry (LA-IRMS). Concentration gradients, particularly of calcium and sulfur, with different spatial extents could be identified by μXRF. NanoSIMS and LA-IRMS detected the release of 13C into soil up to a distance of 100 μm from the root surface, whereas 15N accumulated preferentially in the root cells. We conclude that combining targeted sampling of the soil-root system and correlative microscopy opens new avenues for unraveling rhizosphere processes in situ.

AB - Examining in situ processes in the soil rhizosphere requires spatial information on physical and chemical properties under undisturbed conditions. We developed a correlative imaging workflow for targeted sampling of roots in their three-dimensional (3D) context and assessed the imprint of roots on chemical properties of the root-soil contact zone at micrometer to millimeter scale. Maize (Zea mays) was grown in 15N-labeled soil columns and pulse-labeled with 13CO2 to visualize the spatial distribution of carbon inputs and nitrogen uptake together with the redistribution of other elements. Soil columns were scanned by X-ray computed tomography (X-ray CT) at low resolution (45 μm) to enable image-guided subsampling of specific root segments. Resin-embedded subsamples were then analyzed by X-ray CT at high resolution (10 μm) for their 3D structure and chemical gradients around roots using micro-X-ray fluorescence spectroscopy (μXRF), nanoscale secondary ion mass spectrometry (NanoSIMS), and laser-ablation isotope ratio mass spectrometry (LA-IRMS). Concentration gradients, particularly of calcium and sulfur, with different spatial extents could be identified by μXRF. NanoSIMS and LA-IRMS detected the release of 13C into soil up to a distance of 100 μm from the root surface, whereas 15N accumulated preferentially in the root cells. We conclude that combining targeted sampling of the soil-root system and correlative microscopy opens new avenues for unraveling rhizosphere processes in situ.

KW - 2D−3D registration

KW - distance maps

KW - laser-ablation isotope ratio mass spectrometry

KW - micro-X-ray fluorescence spectroscopy

KW - nanoscale secondary ion mass spectrometry

KW - X-ray computed tomography

KW - Zea mays L.

U2 - 10.1021/acs.est.2c07340

DO - 10.1021/acs.est.2c07340

M3 - Journal article

C2 - 36626664

AN - SCOPUS:85146289862

VL - 57

SP - 1538

EP - 1549

JO - Environmental Science & Technology

JF - Environmental Science & Technology

SN - 0013-936X

IS - 3

ER -