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Synchrotron-based X-ray absorption near-edge spectroscopy imaging for laterally resolved speciation of selenium in fresh roots and leaves of wheat and rice.

Wang P, Menzies NW, Lombi E, McKenna BA, James S, Tang C, Kopittke PM - J. Exp. Bot. (2015)

Bottom Line: Indeed, even in the rhizodermis which is exposed directly to the bulk solution, only 12-31% of the Se was present as uncomplexed selenate.In a similar manner, for plants exposed to selenite, the Se was efficiently converted to C-Se-C compounds within the roots, with only a small proportion of uncomplexed selenite observed within the outer root tissues.This resulted in a substantial decrease in translocation of Se from the roots to leaves of selenite-exposed plants.

View Article: PubMed Central - PubMed

Affiliation: The University of Queensland, School of Agriculture and Food Sciences, St. Lucia, Queensland, 4072, Australia p.wang3@uq.edu.au.

No MeSH data available.


Related in: MedlinePlus

Wheat (Triticum aestivum L.) roots exposed to nutrient solution containing 1 μM Se(VI) for 1 week. A full description is given in the legend of Fig. 1. (A and B) Elemental survey maps showing total Se distribution collected in the ‘pre-XANES survey scan’ followed by fluorescence-XANES imaging (‘XANES imaging scan’), with the white box (0.97 mm×0.60mm) indicating the area examined by XANES imaging. (C) The spatial distribution of three pixel populations (outer, middle, and inner) identified by comparing energy intensities. (D) Normalized Se K-edge XANES spectra corresponding to the three pixel populations ‘outer’, ‘middle’, and ‘inner’ shown in (C) plus the spectrum for MeSeCys. (E and F) Projected volumetric concentrations of C-Se-C compounds (i.e. MeSeCys or SeMet, filled circles) and uncomplexed Se(VI) (open circles) in the cross- or longitudinal transects indicated by the red or green rectangle in (B).
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Figure 5: Wheat (Triticum aestivum L.) roots exposed to nutrient solution containing 1 μM Se(VI) for 1 week. A full description is given in the legend of Fig. 1. (A and B) Elemental survey maps showing total Se distribution collected in the ‘pre-XANES survey scan’ followed by fluorescence-XANES imaging (‘XANES imaging scan’), with the white box (0.97 mm×0.60mm) indicating the area examined by XANES imaging. (C) The spatial distribution of three pixel populations (outer, middle, and inner) identified by comparing energy intensities. (D) Normalized Se K-edge XANES spectra corresponding to the three pixel populations ‘outer’, ‘middle’, and ‘inner’ shown in (C) plus the spectrum for MeSeCys. (E and F) Projected volumetric concentrations of C-Se-C compounds (i.e. MeSeCys or SeMet, filled circles) and uncomplexed Se(VI) (open circles) in the cross- or longitudinal transects indicated by the red or green rectangle in (B).

Mentions: The results for wheat roots exposed to Se(VI) were similar to those for rice (Fig. 5). On average, a total of 9% of the Se was present as uncomplexed Se(VI) whilst 91% was present as C-Se-C compounds (data not presented). Unlike in rice roots, there was no obvious decrease in the proportion of Se present as uncomplexed Se(VI) with increasing distance from the surface of wheat roots (Table 2; Fig. 5D). However, within a virtual longitudinal transect, the concentration (and proportion) of this uncomplexed Se(VI) was again observed to increase with increasing distance from the root apex (Fig. 5F). Indeed, the concentrations of uncomplexed Se(VI) increased from 21 μg cm–3 (i.e. 4.1% of the total Se, at 500 μm from the apex) to 91 μg cm–3 (i.e. 15% of the total Se, at 1100 μm).


Synchrotron-based X-ray absorption near-edge spectroscopy imaging for laterally resolved speciation of selenium in fresh roots and leaves of wheat and rice.

Wang P, Menzies NW, Lombi E, McKenna BA, James S, Tang C, Kopittke PM - J. Exp. Bot. (2015)

Wheat (Triticum aestivum L.) roots exposed to nutrient solution containing 1 μM Se(VI) for 1 week. A full description is given in the legend of Fig. 1. (A and B) Elemental survey maps showing total Se distribution collected in the ‘pre-XANES survey scan’ followed by fluorescence-XANES imaging (‘XANES imaging scan’), with the white box (0.97 mm×0.60mm) indicating the area examined by XANES imaging. (C) The spatial distribution of three pixel populations (outer, middle, and inner) identified by comparing energy intensities. (D) Normalized Se K-edge XANES spectra corresponding to the three pixel populations ‘outer’, ‘middle’, and ‘inner’ shown in (C) plus the spectrum for MeSeCys. (E and F) Projected volumetric concentrations of C-Se-C compounds (i.e. MeSeCys or SeMet, filled circles) and uncomplexed Se(VI) (open circles) in the cross- or longitudinal transects indicated by the red or green rectangle in (B).
© Copyright Policy - creative-commons
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4507780&req=5

Figure 5: Wheat (Triticum aestivum L.) roots exposed to nutrient solution containing 1 μM Se(VI) for 1 week. A full description is given in the legend of Fig. 1. (A and B) Elemental survey maps showing total Se distribution collected in the ‘pre-XANES survey scan’ followed by fluorescence-XANES imaging (‘XANES imaging scan’), with the white box (0.97 mm×0.60mm) indicating the area examined by XANES imaging. (C) The spatial distribution of three pixel populations (outer, middle, and inner) identified by comparing energy intensities. (D) Normalized Se K-edge XANES spectra corresponding to the three pixel populations ‘outer’, ‘middle’, and ‘inner’ shown in (C) plus the spectrum for MeSeCys. (E and F) Projected volumetric concentrations of C-Se-C compounds (i.e. MeSeCys or SeMet, filled circles) and uncomplexed Se(VI) (open circles) in the cross- or longitudinal transects indicated by the red or green rectangle in (B).
Mentions: The results for wheat roots exposed to Se(VI) were similar to those for rice (Fig. 5). On average, a total of 9% of the Se was present as uncomplexed Se(VI) whilst 91% was present as C-Se-C compounds (data not presented). Unlike in rice roots, there was no obvious decrease in the proportion of Se present as uncomplexed Se(VI) with increasing distance from the surface of wheat roots (Table 2; Fig. 5D). However, within a virtual longitudinal transect, the concentration (and proportion) of this uncomplexed Se(VI) was again observed to increase with increasing distance from the root apex (Fig. 5F). Indeed, the concentrations of uncomplexed Se(VI) increased from 21 μg cm–3 (i.e. 4.1% of the total Se, at 500 μm from the apex) to 91 μg cm–3 (i.e. 15% of the total Se, at 1100 μm).

Bottom Line: Indeed, even in the rhizodermis which is exposed directly to the bulk solution, only 12-31% of the Se was present as uncomplexed selenate.In a similar manner, for plants exposed to selenite, the Se was efficiently converted to C-Se-C compounds within the roots, with only a small proportion of uncomplexed selenite observed within the outer root tissues.This resulted in a substantial decrease in translocation of Se from the roots to leaves of selenite-exposed plants.

View Article: PubMed Central - PubMed

Affiliation: The University of Queensland, School of Agriculture and Food Sciences, St. Lucia, Queensland, 4072, Australia p.wang3@uq.edu.au.

No MeSH data available.


Related in: MedlinePlus