Arabidopsis IRON DEFICIENCY TOLERANT1 for iron biofortification and heavy metal phytoremediation.

Iron (Fe) is an essential element for all organisms. Fe deficiency-related health defects, especially anemia, is a big challenge to human health. In addition, imbalanced Fe homeostasis affects plants development and productivity in agricultural system. We identified a dominant and unique allele idt1 in Arabidopsis which confers metal tolerance and Fe accumulation phenotype. The amino acid substitution at C-terminal PPVA motif of IDT1/bHLH34 led to constitutive activation of Fe assimilation. The PPVA motif is responsible for Fe-regulated protein stability of IDT1/bHLH34 and highly conserved among homologs in different plant species. The mutation stabilizes IDT1/bHLH34 protein accumulation and justifies its role as a central regulator of Fe homeostasis. In addition, the finding is an intriguing molecular evidence to support the hypothesis that strengthened capacity for Fe homeostasis from upstream of the pathway can assist Fe biofortification and rescue disorders from heavy metal stresses.