ORCID Profile
0000-0003-1714-5452
Current Organisation
Deutsches Elektronen-Synchrotron DESY
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Publisher: Oxford University Press (OUP)
Date: 25-07-2023
DOI: 10.1093/AOB/MCAD110
Abstract: Selenium hyperaccumulator species are of primary interest for studying the evolution of hyperaccumulation and biofortification as selenium is an essential element in human nutrition. We aimed to determine whether the distributions of selenium in Astragalus bisulcatus, Stanleya pinnata and Neptunia lexicaulis are similar or contrasting to infer the underlying physiological mechanisms. This study used synchrotron-based X-ray Fluorescence Microscopy techniques to visualize the distribution of selenium and other elements in fresh hydrated plant tissues of Astragalus racemosus, Stanleya pinnata and Neptunia lexicaulis. Selenium distribution widely differs in the three species: in the leaves of the A. racemosus and N. lexicaulis Se is mainly concentrated in pulvini, whereas in S. pinnata it is located in leaf margins. In roots and stems of all species selenium was absent in xylem cells, while it was particularly concentrated in pith rays of S. pinnata and phloem cells of A. racemosus and N. lexicaulis. This study shows that Astragalus, Stanleya and Neptunia have evolved different selenium handling physiologies, resulting in different mechanisms for translocation and storage of excess selenium. Important dissimilarities among the three analyzed species suggests that Se hyperaccumulation has likely evolved multiple times under similar environmental pressures.
Publisher: Oxford University Press (OUP)
Date: 02-2022
Abstract: The molecular biology and genetics of the Ni–Cd–Zn hyperaccumulator Noccaea caerulescens has been extensively studied, but no information is yet available on Ni and Zn redistribution and mobilization during seed germination. Due to the different physiological functions of these elements, and their associated transporter pathways, we expected differential tissue distribution and different modes of translocation of Ni and Zn during germination. This study used synchrotron X-ray fluorescence tomography techniques as well as planar elemental X-ray imaging to elucidate elemental (re)distribution at various stages of the germination process in contrasting accessions of N. caerulescens. The results show that Ni and Zn are both located primarily in the cotyledons of the emerging seedlings and Ni is highest in the ultramafic accessions (up to 0.15 wt%), whereas Zn is highest in the calamine accession (up to 600 μg g–1). The distribution of Ni and Zn in seeds was very similar, and neither element was translocated during germination. The Fe maps were especially useful to obtain spatial reference within the seeds, as it clearly marked the vasculature. This study shows how a multimodal combination of synchrotron techniques can be used to obtain powerful insights about the metal distribution in physically intact seeds and seedlings.
Publisher: Oxford University Press (OUP)
Date: 2022
Abstract: 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 s le preparation methods, including sectioning, for synchrotron X-ray fluorescence microscopy (XFM). X-ray fluorescence microscopy-computed tomography (XFM–CT) enables “virtual sectioning” of a s le thereby entirely avoiding artefacts arising from destructive s le preparation. The method can be used on frozen-hydrated s les, 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.
Publisher: Oxford University Press (OUP)
Date: 2019
DOI: 10.1039/C9MT00106A
Abstract: Hyperaccumulator plants present the ideal model system for studying the physiological regulation of the essential (and potentially toxic) transition elements nickel and zinc.
Publisher: Elsevier BV
Date: 09-2022
Publisher: CSIRO Publishing
Date: 13-07-2022
DOI: 10.1071/BT22012
Abstract: Context Hyperaccumulator plants are of considerable interest for their extreme physiology. Stackhousia tryonii is a nickel (Ni) hyperaccumulator plant endemic to ultramafic outcrops in Queensland (Australia) capable of attaining up to 41 300 μg g−1 foliar Ni. Aims This study sought to elucidate the distribution of Ni in S. tryonii by using synchrotron X-ray fluorescence micro-computed tomography (XFM-CT), complemented with elemental maps acquired from physically sectioned plant organs. Its Ni-enriched cylindrical photosynthetic stems make them particularly well suited s les for synchrotron XFM-CT. Methods XFM-CT enables ‘virtual sectioning’ of a s le, avoiding artefacts arising from physical s le preparation. The method can be used on fresh s les that are frozen during the analysis, which preserves ‘life-like’ conditions by limiting radiation damage. It also prevents/minimises other artefacts. Key results The results showed that Ni is mainly concentrated in the apoplastic space surrounding epidermal cells, and in some epidermal cell vacuoles. This finding is significant because this ‘free’ solute Ni is likely to be lost during physical sectioning. Conclusions and implications This case study has highlighted the utility of the XFM-CT approach for visualising metals within intact plant organs, which may be used across the plant sciences.
Publisher: Oxford University Press (OUP)
Date: 17-10-2023
Publisher: Oxford University Press (OUP)
Date: 17-08-2023
Abstract: Synchrotron-based micro-X-ray fluorescence analysis (µXRF) is a non-destructive and highly sensitive technique. However, element mapping of rare earth elements (REEs) under standard conditions requires care, since energy-dispersive detectors are not able to differentiate accurately between REEs L-shell X-ray emission lines overlapping with K-shell X-ray emission lines of common transition elements of high concentrations. We aim to test REE element mapping with high-energy interference-free excitation of the REE K-lines on hyperaccumulator plant tissues and compare with measurements with REE L-shell excitation at the microprobe experiment of beamline P06 (PETRA III, DESY). A combination of compound refractive lens optics (CRLs) was used to obtain a micrometre sized focussed incident beam with an energy of 44 keV and an extra-thick silicon drift detector (SDD) optimised for high-energy X-ray detection to detect the K-lines of yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr) and neodymium (Nd) without any interferences due to line overlaps. High-energy excitation from La to Nd in the hyperaccumulator organs was successful but compared to L-line excitation less efficient and therefore slow (∼10-fold slower than similar maps at lower incident energy) due to lower flux and detection efficiency. However, REE K-lines do not suffer significantly from self-absorption, which makes XRF-tomography of millimetre-sized frozen-hydrated plant s les possible. The K-line excitation of REEs at the P06 CRL setup has scope for application in s les that are particularly prone to REE interfering elements, such as soil s les with high concomitant Ti, Cr, Fe, Mn, Ni concentrations.
Publisher: American Chemical Society (ACS)
Date: 31-12-2019
Abstract: The fern
No related grants have been discovered for Dennis Brückner.