title: Spatially resolved analysis of variation in barley (Hordeum vulgare) grain micronutrient accumulation.
abstract: Genetic biofortification requires knowledge on natural variation and the underlying mechanisms of micronutrient accumulation. We therefore studied diversity in grain micronutrient concentrations and spatial distribution in barley (Hordeum vulgare), a genetically tractable model cereal and an important crop with widespread cultivation. We assembled a diverse collection of barley cultivars and landraces and analysed grain micronutrient profiles in genebank material and after three independent cultivations. Lines with contrasting grain zinc (Zn) accumulation were selected for in-depth analysis of micronutrient distribution within the grain by micro-proton-induced X-ray emission (μ-PIXE). Also, we addressed association with grain cadmium (Cd) accumulation. The analysis of > 120 lines revealed substantial variation, especially in grain Zn concentrations. A large fraction of this variation is due to genetic differences. Grain dissection and μ-PIXE analysis of contrasting lines showed that differences in grain Zn accumulation apply to all parts of the grain including the endosperm. Cd concentrations exceeded the Codex Alimentarius threshold in most of the representative barley lines after cultivation in a Cd-contaminated agricultural soil. Two important conclusions for biofortification are: first, high-Zn grains contain more Zn also in the consumed parts of the grain; and second, higher micronutrient concentrations are strongly associated with higher Cd accumulation.
authors.affiliation: Department of Plant Physiology, University of Bayreuth, Universitätsstr. 30, 95447, Bayreuth, Germany.
authors.forename: Amelie
authors.initials: A
authors.lastname: Detterbeck
authors.affiliation: Department of Plant Physiology, University of Bayreuth, Universitätsstr. 30, 95447, Bayreuth, Germany.
authors.forename: Paula
authors.initials: P
authors.lastname: Pongrac
authors.affiliation: Department of Plant Physiology, University of Bayreuth, Universitätsstr. 30, 95447, Bayreuth, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Rensch
authors.affiliation: Department of Plant Physiology, Ruhr University Bochum, Universitätsstr. 150, 44801, Bochum, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Reuscher
authors.affiliation: Jožef Stefan Institute, Jamova 39, SI-1000, Ljubljana, Slovenia.
authors.forename: Matic
authors.initials: M
authors.lastname: Pečovnik
authors.affiliation: Jožef Stefan Institute, Jamova 39, SI-1000, Ljubljana, Slovenia.
authors.forename: Primož
authors.initials: P
authors.lastname: Vavpetič
authors.affiliation: Jožef Stefan Institute, Jamova 39, SI-1000, Ljubljana, Slovenia.
authors.forename: Primož
authors.initials: P
authors.lastname: Pelicon
authors.affiliation: Bayreuth Center for Ecology and Environmental Research, University of Bayreuth, Dr.-Hans-Frisch-Str. 1-3, 95440, Bayreuth, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Holzheu
authors.affiliation: Department of Plant Physiology, Ruhr University Bochum, Universitätsstr. 150, 44801, Bochum, Germany.
authors.forename: Ute
authors.initials: U
authors.lastname: Krämer
authors.affiliation: Department of Plant Physiology, University of Bayreuth, Universitätsstr. 30, 95447, Bayreuth, Germany.|Bayreuth Center for Ecology and Environmental Research, University of Bayreuth, Dr.-Hans-Frisch-Str. 1-3, 95440, Bayreuth, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Clemens
mesh_terms: D005838:Genotype; D001467:Hordeum / Q000235:genetics / Q000378:metabolism*; D018977:Micronutrients / Q000378:metabolism*; D012044:Regression Analysis; D012639:Seeds / Q000378:metabolism*; D012987:Soil / Q000737:chemistry; D013052:Spectrometry, X-Ray Emission; D014131:Trace Elements
chemical_list: D018977:Micronutrients; D012987:Soil; D014131:Trace Elements
keywords: barley (Hordeum vulgare); biofortification; grain; metal; micro-proton-induced X-ray emission (μ-PIXE); micronutrient accumulation; natural variation