Localization of iron in rice grain using synchrotron X-ray fluorescence microscopy and high resolution secondary ion mass spectrometry

Kyriacou, Bianca; Moore, Katie L.; Paterson, David; Jonge, Martin D. de; Howard, Daryl L.; Stangoulis, James; Tester, Mark; Lombi, Enzo; Johnson, Alexander

doi:10.1016/j.jcs.2013.12.006

Cited by 70 publications

(58 citation statements)

References 30 publications

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“…Note a small piece of parafilm (ICMH 1201), which is rich in Ca and P that was used to securely place the grain. grains, which is typified by high concentrations of several important minerals within the socalled cereal 'bran' layers; whilst much lower concentration levels are localised within the starchy endosperm [33,34].…”

Section: Resultsmentioning

confidence: 99%

Micro-PIXE mapping of mineral distribution in mature grain of two pearl millet cultivars

Minnis‐Ndimba

Kruger

Taylor

et al. 2015

Nuclear Instruments and Methods in Physics Research Section B:

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Micro-proton-induced X-ray Emission (micro-PIXE) was used to map the distribution of several nutritionally important minerals found in the grain tissue of two cultivars of pearl millet (Pennisetum glaucum (L.) R. Br.). The distribution maps revealed that the predominant localisation of mineral elements was within the germ (consisting of the scutellum and embryo) and the outer grain layers (specifically the pericarp and aleurone); whilst the bulk of the endosperm tissue featured relatively low concentrations of the surveyed minerals. Within the germ, the scutellum was revealed as a major storage tissue for P and K; whilst Ca, Mn and Zn were more prominent within the embryo. Fe was revealed to have a distinctive distribution pattern, confined to the dorsal end of the scutellum; but was also highly concentrated in the outer grain layers. Interestingly, the hilar region was also revealed as a site of high accumulation of mineral elements, particularly for S, Ca, Mn, Fe and Zn, which may be part of a defensive strategy against infection or damage. Differences between the two cultivars, in terms of the bulk Fe and P content obtained via inductively coupled plasma optical emission spectrometry (ICP-OES), concurred with the average concentration data determined from the analysis of micro-PIXE spectra specifically extracted from the endosperm tissue.

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Section: Resultsmentioning

confidence: 99%

Micro-PIXE mapping of mineral distribution in mature grain of two pearl millet cultivars

Minnis‐Ndimba

Kruger

Taylor

et al. 2015

Nuclear Instruments and Methods in Physics Research Section B:

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“…Line scans across the crease region showed similar Zn signal intensities in CE-1 and NS modified aleurone cells yet higher Zn signal intensity in the CE-1 nucellar projection (Figure 3e-f; Figure S4), a tissue which has been shown to contain NA-bound Fe (De Brier et al, 2016), and this difference likely accounts for the observed Zn concentration increase in CE-1 white flour (Figure 6b). Interestingly, synchrotron XFM studies of rice grain reveal a radically different Zn distribution pattern that extends throughout the endosperm and shows no obvious barrier to endosperm loading (Johnson et al, 2011;Kyriacou et al, 2014). Determining whether differences in transport mechanisms or sink strength account for the Zn distribution differences between wheat and rice grain merits further investigation.…”

Section: Discussionmentioning

confidence: 99%

Metabolic engineering of bread wheat improves grain iron concentration and bioavailability

Beasley

Bonneau

Sánchez-Palacios

et al. 2019

Plant Biotechnology Journal

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Summary Bread wheat ( Triticum aestivum L.) is cultivated on more land than any other crop and produces a fifth of the calories consumed by humans. Wheat endosperm is rich in starch yet contains low concentrations of dietary iron (Fe) and zinc (Zn). Biofortification is a micronutrient intervention aimed at increasing the density and bioavailability of essential vitamins and minerals in staple crops; Fe biofortification of wheat has proved challenging. In this study we employed constitutive expression ( CE ) of the rice ( Oryza sativa L.) nicotianamine synthase 2 ( Os NAS 2 ) gene in bread wheat to up‐regulate biosynthesis of two low molecular weight metal chelators – nicotianamine ( NA ) and 2′‐deoxymugineic acid ( DMA ) – that play key roles in metal transport and nutrition. The CE ‐ Os NAS 2 plants accumulated higher concentrations of grain Fe, Zn, NA and DMA and synchrotron X‐ray fluorescence microscopy ( XFM ) revealed enhanced localization of Fe and Zn in endosperm and crease tissues, respectively. Iron bioavailability was increased in white flour milled from field‐grown CE ‐ Os NAS 2 grain and positively correlated with NA and DMA concentrations.

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“…Interestingly, knockout mutants of VIT1 and VIT2 in rice accumulated more iron in the embryo (Zhang et al, 2012). A likely scenario is that iron distributed to the developing rice grain cannot enter the vacuoles in the aleurone (Kyriacou et al, 2014) and, thus, is diverted to the embryo. This finding further supports the idea that VITs play a key role in iron distribution in cereal grains.…”

Section: Discussionmentioning

confidence: 99%

Wheat Vacuolar Iron Transporter TaVIT2 Transports Fe and Mn and Is Effective for Biofortification

et al. 2017

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Localization of iron in rice grain using synchrotron X-ray fluorescence microscopy and high resolution secondary ion mass spectrometry

Cited by 70 publications

References 30 publications

Micro-PIXE mapping of mineral distribution in mature grain of two pearl millet cultivars

Micro-PIXE mapping of mineral distribution in mature grain of two pearl millet cultivars

Metabolic engineering of bread wheat improves grain iron concentration and bioavailability

Wheat Vacuolar Iron Transporter TaVIT2 Transports Fe and Mn and Is Effective for Biofortification

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