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. 2023 Nov 30;13(1):21132.
doi: 10.1038/s41598-023-46056-5.

Mercury speciation in selenium enriched wheat plants hydroponically exposed to mercury pollution

Nithyapriya Manivannan  1   2 , Maria Angels Subirana  2 , Roberto Boada  1   2 , Carlo Marini  1 , Mercè Llugany  3 , Manuel Valiente  2 , Laura Simonelli  4
Affiliations

Mercury speciation in selenium enriched wheat plants hydroponically exposed to mercury pollution

Nithyapriya Manivannan et al. Sci Rep. .

Abstract

Mercury (Hg) pollution in agricultural soils and its potential pathway to the human food chain can pose a serious health concern. Understanding the pathway of Hg in plants and how the speciation may change upon interaction with other elements used for biofortification can be critical to assess the real implications for the final plant-based product. In that respect, selenium (Se) biofortification of crops grown in Se-poor soil regions is becoming a common practice to overcome Se deficient diets. Therefore, it is important to assess the interplay between these two elements since Se may form complexes with Hg reducing its bioavailability and toxicity. In this work, the speciation of Hg in wheat plants grown hydroponically under the presence of Hg (HgCl2) and biofortified with Se (selenite, selenate, or a 1:1 mixture of both) has been investigated by X-ray absorption spectroscopy at the Hg L3-edge. The main Hg species found in wheat grains was the highly toxic methylmercury. It was found that the Se-biofortification of wheat did not prevent, in general, the Hg translocation to grains. Only the 1:1 mixture treatment seemed to have an effect in reducing the levels of Hg and the presence of methylmercury in grains.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Figure 1
Figure 1
Concentration of Hg (mg·kg−1 DW) in different parts of the wheat plant grown under different Se bio-fortification treatments and Hg pollution. Error bar represents standard error from three measurements.
Figure 2
Figure 2
Normalized Hg L3-edge XANES (a), k2-weighted EXAFS signal (b), and corresponding Fourier transforms (c) of spectra acquired over different part of the plants grown with different Se and Hg treatments. The vertical lines are a guide for the eye to identify the main spectral features.
Figure 3
Figure 3
HERFD-XANES spectra collected at the Hg L3-edge in the root samples grown with different treatments.
Figure 4
Figure 4
Results from the LCF analysis of the XANES spectra of different parts of the plants (R: roots, S: shoots, G: grain) under different treatments.
See this image and copyright information in PMC

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