[Wolfgang Schmidt] Iron Man to the rescue

Iron is an essential mineral nutrient which severely affects the growth, yield, and nutritional quality of plants if not supplied in sufficient quantities. Wolfgang Schmidt’s group discovered a novel family of peptides in plants referred to as IRON MAN (IMA), and show that they are a sine qua non for the uptake of iron the soil. Silencing of all eight IMA genes in Arabidopsis by CRISPR-Cas9 genome editing resulted in very small, extremely chlorotic plants that died without drastic iron supplementation. IMAs are present in the genomes of all flowering plants but are missing in ferns, algae or fungi, suggesting that IMA emerged at an early stage in the evolution of land plants. Reciprocal grafting of octuple ima mutants with wild-type plants showed that IMA1 peptides in shoots positively regulate iron uptake in roots, suggesting that IMAs are the long sought-after shoot-borne signal that communicates the iron status of the leaves to tune iron uptake by roots. The discovery of IRON MAN opens a novel route of generating iron-enriched plants that may help to combat iron deficiency-induced anaemia, one of the largest nutritional disorder in humans.