*5.3. Statistical Analysis*

Pairwise comparisons were tested by Student *t*-test at *p* < 0.05 and linear regression analysis was performed in SigmaPlot version 13.0 (Systat Software, San Jose, CA). Clustering and heatmap was created using z-transformed average total concentrations in whole grain using function heatmap.2 in gplots package within R i386 3.0.2 software.

**Supplementary Materials:** The following are available online at http://www.mdpi.com/2223-7747/9/1/79/s1. Figure S1: Hierarchical clustering and heatmap of grain elemental composition of all wheat cultivars studied. Figure S2: Correlations between element concentrations in whole grain for all wheat cultivars studied. Figure S3: Correlations between element concentrations in whole grain for the selected four wheat cultivars. Figure S4: Quantitative distribution maps in the grain of awned wheat cultivars. Figure S5: Quantitative distribution maps in the grain of awnletted wheat cultivars. Figure S6: Iron K-edge XANES of reference compounds used in the linear combination fitting. Table S1: Agronomic characteristics of the wheat cultivars studied. Table S2: Relative amounts of iron ligands in the grain wheat cultivars and in di fferent grain tissues.

**Author Contributions:** Formal analysis, P.P., I.A. and K.V.-M.; investigation, P.P., I.A., H.C.-M. and K.V.-M.; project administration, K.V.-M.; visualization, P.P.; writing—original draft, P.P., H.C.-M. and K.V.-M. All authors have read and agreed to the published version of the manuscript.

**Funding:** The study was financed by the Slovenian Research Agency (ARRS) through programmes (P1-0212, P1-0112 and I0-0005), and projects (N7-077, J7-9418, J7-9398, N1-0105 and N1-0090).

**Acknowledgments:** The European Synchrotron Radiation Facility (ESRF), Grenoble, France, is acknowledged for the provision of synchrotron radiation facilities at beamline ID21 (experiment number LS-2225) and Elettra, Trieste, Italy, for access to the synchrotron radiation facilities at beamline XAFS (experiment number 20185165). The authors are grateful to Giuliana Aquilanti and Simone Pollastri from XAFS beamline of ELETTRA for expert advice on beamline operation and to Darinka Koron from the Agricultural Institute of Slovenia for kindly providing the grain of the wheat cultivars studied.

**Conflicts of Interest:** The authors declare no conflict of interest.
