Landscape of Micronutrient Uptake and Transport in Wheat and Implications for Grain Biofortification

It is estimated that more than two billion people worldwide are affected by micronutrient malnutrition, mainly of iron (Fe) and zinc (Zn). While breeding efforts have centered on increasing Fe and Zn concentrations in grains, little is known as to what makes a plant efficient in Fe and Zn uptake, transport, and storage. Furthermore, the impact of environments with low micronutrient levels on the plant health is not clear. To elucidate these mechanisms, three replicates of two spring wheat lines – Glenlea and Red Fife – were grown in two environments with Hoagland solution containing: 1) Fe and Zn at 45 μM and 0.5 μM concentrations, respectively; and 2) Fe and Zn both at 0 μM. Twenty-one-day old seedlings were harvested for ionome profiling and transcriptome sequencing. Ionome analysis revealed that root concentrations of both Fe and Zn in both lines were several folds higher than that in the shoot. In particular, Glenlea had the lowest Fe and Zn concentrations in both root and shoot tissues whereas Red Fife had the highest. Upon aligning the sequence reads to currently available wheat transcripts on Ensembl, we identified 606-2,136 responsive transcripts in roots and shoots. In addition to tissue-specific gene expression, we also noticed that majority of down-regulated genes in Glenlea were up-regulated in Red Fife, and vice-versa. Further, we expect to identify polymorphisms in highly active transcripts which could be used as markers breed for lines that are efficient in micronutrient uptake and deposition in grains.