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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(IV) 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 two pixel populations (outer and inner) identified by comparing energy intensities. (D) Normalized Se K-edge XANES spectra corresponding to the two pixel populations ‘outer’ 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(IV) (open circles) in the cross- and longitudinal transects indicated by the red or green rectangle in (B).
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Figure 2: Wheat (Triticum aestivum L.) roots exposed to nutrient solution containing 1 μM Se(IV) 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 two pixel populations (outer and inner) identified by comparing energy intensities. (D) Normalized Se K-edge XANES spectra corresponding to the two pixel populations ‘outer’ 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(IV) (open circles) in the cross- and longitudinal transects indicated by the red or green rectangle in (B).

Mentions: For wheat roots exposed to Se(IV), the pattern of Se accumulation and speciation was similar to that described above for rice. Specifically, the highest concentrations of Se were again found in the apical tissues (~50–1000 μm from the root apex), with concentrations being lower in the more proximal root tissues (Fig. 2). Most of the Se within the root tissues was present as C-Se-C compounds (averaged 98% across the entire region of analysis) with only 2% present as uncomplexed Se(IV). Analysis of the spatial distribution of these Se species showed that the proportion of Se present as Se(IV) was highest in the outer tissues and was lowest in the inner tissues (Table 2; Fig. 2C). Indeed, the mathematical model estimated that the concentration of uncomplexed Se(IV) decreased from 8 μg g–1 in the rhizodermis to ≤3.4 μg g–1 in the stele and cortex, with the remainder of the Se present as C-Se-C compounds (Tables 2, 23).


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(IV) 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 two pixel populations (outer and inner) identified by comparing energy intensities. (D) Normalized Se K-edge XANES spectra corresponding to the two pixel populations ‘outer’ 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(IV) (open circles) in the cross- and 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 2: Wheat (Triticum aestivum L.) roots exposed to nutrient solution containing 1 μM Se(IV) 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 two pixel populations (outer and inner) identified by comparing energy intensities. (D) Normalized Se K-edge XANES spectra corresponding to the two pixel populations ‘outer’ 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(IV) (open circles) in the cross- and longitudinal transects indicated by the red or green rectangle in (B).
Mentions: For wheat roots exposed to Se(IV), the pattern of Se accumulation and speciation was similar to that described above for rice. Specifically, the highest concentrations of Se were again found in the apical tissues (~50–1000 μm from the root apex), with concentrations being lower in the more proximal root tissues (Fig. 2). Most of the Se within the root tissues was present as C-Se-C compounds (averaged 98% across the entire region of analysis) with only 2% present as uncomplexed Se(IV). Analysis of the spatial distribution of these Se species showed that the proportion of Se present as Se(IV) was highest in the outer tissues and was lowest in the inner tissues (Table 2; Fig. 2C). Indeed, the mathematical model estimated that the concentration of uncomplexed Se(IV) decreased from 8 μg g–1 in the rhizodermis to ≤3.4 μg g–1 in the stele and cortex, with the remainder of the Se present as C-Se-C compounds (Tables 2, 23).

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