From the stars to your table - plants as complex conduits for iron nutrition

Iron is a ubiquitous micronutrient that plays critical roles in central metabolic processes for all living organisms. The mechanisms by which plants extract iron from soil and maintain iron homeostasis are particularly intriguing. While it is relatively abundant, in most soils iron is insoluble and therefore of limited bioavailability, however excess iron accumulation in plants can lead to cellular damage. Thus, plants must extract sufficient quantities of iron from recalcitrant soil environments, while also ensuring that iron content does not exceed a specific range. Arabidopsis and other dicots have evolved mechanisms to sense iron deficiency in the shoot, which triggers roots to solubilize, reduce and uptake iron across multiple root cell types before transport to the shoot. Using a combination of molecular and confocal microscopy analysis, cell-type specific transcriptional profiling, and mathematical modeling we have uncovered several molecular mechanisms that control how plants recognize and respond to iron deficiency stress in a root cell-specific manner. Our findings provide new evidence for how distinct alternations in the root cortex control carbon metabolism in response to iron deprivation, and how iron deficiency causes specific developmental alterations in the root vasculature and epidermis. Together, these mechanisms operate to fine-tune root growth and physiology in the face of suboptimal growth conditions, while also providing new avenues for exploring inter- and intracellular nutrient stress response in plants.