Cadmium distribution in mature durum wheat grains using dissection, laser ablation-ICP-MS and synchrotron techniques

Abstract

Understanding how essential and toxic elements are distributed in cereal grains is a key to improving the nutritional quality of cereal-based products. The main objective of this work was to characterize the distribution of Cd and of nutrients (notably Cu, Fe, Mn, P, S and Zn) in the durum wheat grain. Laser ablation inductively coupled mass spectrometry and synchrotron micro X-ray fluorescence were used for microscale mapping of Cd and nutrients. A dissection approach was used to quantitatively assess the distribution of Cd and nutrients among grain tissues. Micro X-ray absorption near-edge spectroscopy was used to identify the Cd chemical environment in the crease. Cadmium distribution was characterized by strong accumulation in the crease and by non-negligible dissemination in the endosperm. Inside the crease, Cd accumulated most in the pigment strand where it was mainly associated with sulfur ligands. High-resolution maps highlighted very specific accumulation areas of some nutrients in the germ, for instance Mo in the root cortex primordia and Cu in the scutellum. Cadmium loading into the grain appears to be highly restricted. In the grain, Cd co-localized with several nutrients, notably Mn and Zn, which challenges the idea of selectively removing Cd-enriched fractions by dedicated milling process. Main finding of the workThis work provides the first high-resolution maps of Cd distribution in durum wheat grain and, thereby, adds to our understanding of the processes involved in Cd loading and storage in cereal seeds.

Lead smelting alters wheat flour heavy metal concentrations and health risks

“…Concentrations of Cu, Pb, and Zn concentrations in wheat samples (Table 1; Supplemental Table S3) were similar to those found in earlier works (e.g., Cardoso et al., 2018; Cubadda et al., 2005; Giordano & Blandino, 2018; Yan et al., 2020). Pearling, or the removal of wheat bran, also affected heavy metal distribution in different wheat grain fractions (Table 1; Supplemental Table S3).…”

Changes of Cadmium Storage Forms and Isotope Ratios in Rice During Grain Filling

“…The results that Cd was fully bound to S in the nodes, the majority of Cd in the grains was bound to S ( Figure 4b ), and no isotope fractionation occurred between the node, panicle, and grains ( Figure 3B ) suggest that Cd was transported as Cd–S from the nodes into the grains. A transport from the node to the grain without ligand exchange would require that Cd is transported as Cd–S complex from the node via phloem directly into the grain crease ( Yan et al, 2020 ). Little is known how Cd and metals are transported from the nodes into the phloem.…”

“…This observation coincides with previously published size exclusion ICP-MS data that identified S-bearing proteins as the major storage form of Cd in rice ( Wei et al, 2017 ). In addition, μXANES studies revealed that large fractions of up to 92% of Cd can be bound to S in rice and wheat grains ( Gu et al, 2020 ; Yan et al, 2020 ). The consistent findings that S can be an important binding site for Cd may have implications on Cd absorption in human nutrition ( Gu et al, 2020 ).…”

“…Size exclusion chromatography–inductively coupled plasma mass spectrometry (ICP-MS) techniques ( Wei et al, 2017 ) indicated that the major fraction of Cd was stored with S-rich protein fractions in rice. Recent X-ray absorption spectroscopy (XAS) studies for rice and wheat showed that Cd–S can be an important storage form in grains (27–92%, Gu et al, 2020 ; Yan et al, 2020 ). To date, no study reported Cd storage forms in rice roots, shoots, and grains and how these storage forms change at different growth stages.…”

Thiolated poly(aspartic acid)-functionalized two-dimensional MoS2, chitosan and bismuth film as a sensor platform for cadmium ion detection

“…[1][2][3] Cd 2+ not only causes renal tubular dysfunction and bone degeneration (itai-itai disease), [4][5][6] but is also classied as a carcinogenic chemical by the International Agency for Research on Cancer (IARC). [7][8][9] Traditionally, inductively coupled plasma mass spectrometry (ICP-MS), 10,11 atomic absorption spectrometry (ABS) [12][13][14] and ion chromatography 15,16 are used for detecting Cd 2+ . Although these instruments have good precision and high resolution, they are too expensive and laborintensive.…”