1. Temporal and spatial patterns of zinc and iron accumulation during barley (Hordeum vulgare L.) grain development. Journal of agricultural and food chemistry.Amelie Detterbeck, Paula Pongrac, Daniel Persson, Katarina Vogel-Mikuš, Mitja Kelemen, Primož Vaupetič, Primož Pelicon, Iztok Arčon, Søren Husted, Jan Kofod Shjoerring, Stephan Clemens, 2020, izvirni znanstveni članek Opis: Breeding and engineering of biofortified crops will benefit from a better understanding of bottlenecks controlling
micronutrient loading within the seeds. However, few studies have addressed the changes in micronutrient concentrations,
localization, and speciation occurring over time. Therefore, we studied spatial patterns of zinc and iron accumulation during grain
development in two barley lines with contrasting grain zinc concentrations. Microparticle-induced-X-ray emission and laser ablationinductively
coupled plasma mass spectrometry were used to determine tissue-specific accumulation of zinc, iron, phosphorus, and
sulfur. Differences in zinc accumulation between the lines were most evident in the endosperm and aleurone. A gradual decrease in
zinc concentrations from the aleurone to the underlying endosperm was observed, while iron and phosphorus concentrations
decreased sharply. Iron co-localized with phosphorus in the aleurone, whereas zinc co-localized with sulfur in the sub-aleurone. We
hypothesize that differences in grain zinc are largely explained by the endosperm storage capacity. Engineering attempts should be
targeted accordingly.
Ključne besede: barley (Hordeum vulgare L.), biofortification, grain development, grain loading, LA-ICP-MS, μ-PIXE
Objavljeno v RUNG: 20.10.2020; Ogledov: 4044; Prenosov: 0
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2. Arabidopsis halleri shows hyperbioindicator behaviour for Pb and leaf Pb accumulation spatially separated from ZnStephan Höreth, Paula Pongrac, Marta Debeljak, Katarina Vogel-Mikuš, Matic Pečovnik, Primož Vavpetič, Iztok Arčon, izvirni znanstveni članek Opis: Lead (Pb) ranks among the most problematic environmental pollutants. Background contamination of soils is nearly ubiquitous, yet plant Pb accumulation is barely understood. In a survey covering 165 European populations of the metallophyte Arabidopsis halleri, several field samples had indicated Pb hyperaccumulation, offering a chance to dissect plant Pb accumulation.
Accumulation of Pb was analysed in A. halleri individuals from contrasting habitats under controlled conditions to rule out aerial deposition as a source of apparent Pb accumulation. Several elemental imaging techniques were employed to study the spatial distribution and ligand environment of Pb.
Regardless of genetic background, A. halleri individuals showed higher shoot Pb accumulation than A. thaliana. However, dose–response curves revealed indicator rather than hyperaccumulator behaviour. Xylem sap data and elemental imaging unequivocally demonstrated the in planta mobility of Pb. Highest Pb concentrations were found in epidermal and vascular tissues. Distribution of Pb was distinct from that of the hyperaccumulated metal zinc. Most Pb was bound by oxygen ligands in bidentate coordination.
A. halleri accumulates Pb whenever soil conditions render Pb phytoavailable. Considerable Pb accumulation under such circumstances, even in leaves of A. thaliana, strongly suggests that Pb can enter food webs and may pose a food safety risk.
Ključne besede: Pb accumulation, XANES, EXAFS, Arabidopsis halleri
Objavljeno v RUNG: 16.01.2020; Ogledov: 4311; Prenosov: 0
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3. Mineral element composition in grain of awned and awnletted wheat (Triticum aestivum L.) cultivars tissue-specific iron speciation and phytate and non-phytate ligand ratioPaula Pongrac, Iztok Arčon, Hiram Castillo Michel, Katarina Vogel-Mikuš, 2020, izvirni znanstveni članek Opis: In wheat (Triticum aestivum L.), the awns—the bristle-like structures extending from
lemmas—are photosynthetically active. Compared to awned cultivars, awnletted cultivars produce
more grains per unit area and per spike, resulting in significant reduction in grain size, but their
mineral element composition remains unstudied. Nine awned and 11 awnletted cultivars were
grown simultaneously in the field. With no difference in 1000-grain weight, a larger calcium and
manganese—but smaller iron (Fe) concentrations—were found in whole grain of awned than in
awnletted cultivars. Micro X-ray absorption near edge structure analysis of different tissues of
frozen-hydrated grain cross-sections revealed that differences in total Fe concentration were not
accompanied by differences in Fe speciation (64% of Fe existed as ferric and 36% as ferrous species) or
Fe ligands (53% were phytate and 47% were non-phytate ligands). In contrast, there was a distinct
tissue-specificity with pericarp containing the largest proportion (86%) of ferric species and nucellar
projection (49%) the smallest. Phytate ligand was predominant in aleurone, scutellum and embryo
(72%, 70%, and 56%, respectively), while nucellar projection and pericarp contained only non-phytate
ligands. Assuming Fe bioavailability depends on Fe ligands, we conclude that Fe bioavailability from
wheat grain is tissue specific.
Ključne besede: biofortification, phytate, iron, awn, X-ray fluorescence, X-ray absorption spectrometry, phosphorus, sulphur, nicotianamine
Objavljeno v RUNG: 16.01.2020; Ogledov: 3973; Prenosov: 0
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4. Recent advances in 2D imaging of element distribution in Plants by focused beam techniquesKatarina Vogel-Mikuš, Johannes Teun van Elteren, Marjana Regvar, Jitrin Chaiprapa, Boštjan Jenčič, Iztok Arčon, Alojz Kodre, Peter Kump, Anja Kavčič, Mitja Kelemen, Dino Metarapi, Marijan Nečemer, Primož Vavpetič, Primož Pelicon, Paula Pongrac, 2019, samostojni znanstveni sestavek ali poglavje v monografski publikaciji Ključne besede: 2D Imiging, XRF, XANES, synchrotron light
Objavljeno v RUNG: 05.09.2019; Ogledov: 4365; Prenosov: 0
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5. Cadmium localization and chemical environment in a cadmium bioindicator Gomphrena clausseniiPaula Pongrac, Mina T. Villafort Carvalho, Tânia S. Serra, Hiram Castillo Michel, Katarina Vogel-Mikuš, Iztok Arčon, Luka Jeromel, Mitja Kelemen, Boštjan Jenčič, Anja Kavčič, Primož Pelicon, Mark G. M. Aarts, 2018, objavljeni povzetek znanstvenega prispevka na konferenci Ključne besede: cadmium
Objavljeno v RUNG: 12.09.2018; Ogledov: 4745; Prenosov: 0
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6. Cadmium associates with oxalate in calcium oxalate crystals and competes with calcium for translocation to stems in the cadmium bioindicator Gomphrena clausseniiPaula Pongrac, Tania Serra, Hiram Castillo Michel, Katarina Vogel-Mikuš, Iztok Arčon, Mitja Klemen, Boštjan Jencic, Anja Kavčič, Mina T. Villafort Carvalho, Mark G. M. Aarts, 2018, izvirni znanstveni članek Opis: Cadmium (Cd) was shown to co-localise with calcium (Ca) in oxalate crystals in the stems and leaves of
Cd tolerant Gomphrena claussenii, but Cd binding remained unresolved. Using synchrotron radiation
X-ray absorption near edge spectroscopy we demonstrate that in oxalate crystals of hydroponically
grown G. claussenii the vast majority of Cd is bound to oxygen ligands in oxalate crystals (488%;
Cd–O–C coordination) and the remaining Cd is bound to sulphur ligands (Cd–S–C coordination). Cadmium
binding to oxalate does not depend on the amount of Ca supplied or from which organs the crystals
originate (stems and mature leaves). By contrast, roots contain no oxalate crystals and therein Cd is
bound predominantly by S ligands. The potential to remove Cd by extraction of Cd-rich oxalate crystals
from plant material should be tested in phytoextraction or phytomining strategies.
Ključne besede: Cd XANES, Cd oxalate, Gomphrena claussenii
Objavljeno v RUNG: 06.09.2018; Ogledov: 4462; Prenosov: 0
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