Dietary iron and zinc deficiency is a global problem afflicting about one third of the world’s population primarily women and children. This result primarily from poverty that causes eventually leads a too narrow food base consisting almost exclusively of inexpensive starch crops like wheat, maize and rice, crops that have a low content of micronutrients in the endosperm.
During grain filling, seed transfer cells mediate seed loading by directing materials from maternal tissues into the endosperm, the edible part of the grain. Aleurone cells, as the surrounding layer of the endosperm and embryo, contain a considerable proportion of total seed minerals. These parts are excluded from the flour during milling.
Our The research area comprises molecular characterization of genes encoding zinc and iron transporters and genes involved in zinc and iron binding and deposition in the developing wheat and barley grain and the manipulation of these genes by transformation to improve the zinc and iron content of the endosperm. We have previously performed microarray studies based on laser capture microdissection and have established the first roadmap for zinc and iron transport into the barley grain (Tauris et al.2009; Borg et al.2009). We have as one of our primary goals to develop this roadmap further by introducing next generation sequencing on laser capture microdissected tissues comprising the transport pathway from the vegetative tissues into the endosperm. Our second objective is to use this knowledge to improve iron and zinc content and bioavailability of the endosperm by gene manipulation by transformation. Our hypothesis is that it is possible to increase the content of essential minerals in the wheat endosperm by transgenic modulation of mineral transporters and mineral deposition in the endosperm.
Gene manipulation strategies:
•Bypass the normal deposition of zinc in the protein storage vacuole of the aleurone by tissue-specific down-regulation of the vacuolar zinc transporter, MTP1.
•Generate barley plants over expressing the HvHMA2 zinc transporter using unloading zone specific promoters.
•Generation of transgenic wheat overexpressing the wheat TaFer1 gene under the control of the wheat high molecular weight glutenine 1Dx5 promoter in wheat.
•Bypass the normal deposition of iron in the protein storage vacuole of the aleurone by tissue-specific down-regulation of vacuolar iron transporter, Vit1.
•Cross the transgenic lines with lines expressing phytase to improve the bioavailability of divalent mineral cations in the digestive tract of humans and livestock.