Wessells, K. R. & Brown, K. H. Estimating the global prevalence of zinc deficiency: results based on zinc availability in national food supplies and the prevalence of stunting. PLoS One 7, e50568 (2012).
von Grebmer, K. et al. Global hunger index: the challenge of hidden hunger (International Food Policy Research Institute, 2014).
Palmgren, M. G. et al. Zinc biofortification of cereals problems and solutions. Trends Plant Sci. 13, 464–473 (2008).
Stadler, R., Lauterbach, C. & Sauer, N. Cell-to-cell movement of green fluorescent protein reveals post-phloem transport in the outer integument and identifies symplastic domains in Arabidopsis seeds and embryos. Plant Physiol. 139, 701–712 (2005).
Zhang, W. et al. Nutrient loading of developing seeds. Funct. Plant Biol. 34, 314–331 (2007).
Radchuk, V. & Borisjuk, L. Physical, metabolic and developmental functions of the seed coat. Front. Plant Sci. 5, 510 (2014).
Williams, L. E. & Mills, R. F. P1B-ATPases—an ancient family of transition metal pumps with diverse functions in plants. Trends Plant Sci. 10, 491–502 (2005).
Baxter, I. et al. Genomic comparison of P-type ATPase ion pumps in Arabidopsis and rice. Plant Physiol. 132, 618–628 (2003).
Kim, Y.-Y. et al. AtHMA1 contributes to the detoxification of excess Zn(II) in Arabidopsis. Plant J. 58, 737–753 (2009).
Seigneurin-Berny, D. et al. HMA1, a new Cu-ATPase of the chloroplast envelope, is essential for growth under adverse light conditions. J. Biol. Chem. 281, 2882–2892 (2006).
Morel, M. et al. AtHMA3, a P(1B)-ATPase allowing Cd/Zn/Co/Pb vacuolar storage in Arabidopsis. Plant Physiol. 149, 894–904 (2009).
Hussain, D. et al. P-type ATPase heavy metal transporters with roles in essential zinc homeostasis in Arabidopsis. Plant Cell 16, 1327–1339 (2004).
Sinclair, S. A. et al. The use of the zinc-fluorophore, Zinpyr-1, in the study of zinc homeostasis in Arabidopsis roots. New Phytol. 174, 39–45 (2007).
Verret, F. et al. Overexpression of AtHMA4 enhances root-to-shoot translocation of zinc and cadmium and plant metal tolerance. FEBS Lett. 576, 306–312 (2004).
Hanikenne, M. et al. Evolution of metal hyperaccumulation required cis-regulatory changes and triplication of HMA4. Nature 453, 391–396 (2008).
Kim, S. A. et al. Localization of iron in Arabidopsis seed requires the vacuolar membrane transporter VIT1. Science 314, 1295–1298 (2006).
Schnell Ramos, M. et al. Using μPIXE for quantitative mapping of metal concentration in Arabidopsis thaliana seeds. Front Plant Sci. 4, 168 (2013).
Le, B. H. et al. Global analysis of gene activity during Arabidopsis seed development and identification of seed-specific transcription factors. Proc. Natl Acad. Sci. USA 107, 8063–8070 (2010).
Song, W.-Y. et al. Arabidopsis PCR2 is a zinc exporter involved in both zinc extrusion and long-distance zinc transport. Plant Cell 22, 2237–2252 (2010).
Morth, J. P. et al. A structural overview of the plasma membrane Na+,K+-ATPase and H+-ATPase ion pumps. Nature Rev. Mol. Cell Biol. 12, 60–70 (2011).
Mills, R. F. et al. HvHMA2, a P1B-ATPase from barley, is highly conserved among cereals and functions in Zn and Cd transport. PLoS One 7, e42640 (2012).
Tauris, B. et al. A roadmap for zinc trafficking in the developing barley grain based on laser capture microdissection and gene expression profiling. J. Exp. Bot. 60, 1333–1347 (2009).
Satoh-Nagasawa, N. et al. Mutations in rice (Oryza sativa) Heavy Metal ATPase 2 (OsHMA2) restrict the translocation of zinc and cadmium. Plant Cell Physiol. 53, 213–224 (2012).
Takahashi, R. et al. The OsHMA2 transporter is involved in root-to-shoot translocation of Zn and Cd in rice. Plant Cell Environ. 35, 1948–1957 (2012).
Yamaji, N. et al. Preferential delivery of zinc to developing tissues in rice is mediated by P-type heavy metal ATPase OsHMA2. Plant Physiol. 162, 927–939 (2013).
Barabasz, A. et al. Metal accumulation in tobacco expressing Arabidopsis halleri metal hyperaccumulation gene depends on external supply. J. Exp. Bot. 61, 3057–3067 (2010).
Siemianowski, O. et al. Expression of the P1B-type ATPase AtHMA4 in tobacco modifies Zn and Cd root to shoot partitioning and metal tolerance. Plant Biotechnol. J. 9, 64–74 (2011).
Cun, P. et al. Modulation of Zn/Cd P1B2-ATPase activities in Arabidopsis impacts differently on Zn and Cd contents in shoots and seeds. Metallomics 6, 2109–2916 (2014).
Kendziorek, M. et al. Approach to engineer tomato by expression of AtHMA4 to enhance Zn in the aerial parts. J. Plant Physiol. 171, 1413–1422 (2014).
Truernit, E. et al. High-resolution whole-mount imaging of three-dimensional tissue organization and gene expression enables the study of phloem development and structure in Arabidopsis. Plant Cell 20, 1494–1503 (2008).