Integrative spatial transcriptomic analysis pinpoints the role of TaMCO3 encoding ferroxidase in wheat root tip iron mobilization

Iron (Fe) deficiency triggers molecular responses in plant roots, but the specific involvement of root tips in nutrient responses remains unclear. Therefore, in this study, we conducted a transcriptome analysis of wheat root tips under Fe deficiency, and a comparative transcriptome analysis was performed with the total root dataset. Gene ontology analysis highlighted the significance of oxidoreductase activity and metal/ion transport in the root tip tissue, which are critical for iron mobilisation. Interestingly, wheat displayed varying gene expression levels arising from the three genomes (A, B, and D) yet contributed to similar molecular functions. Detailed analysis of the oxidoreductase function in the root tip identified multiple<underline>m</underline>ulti-<underline>c</underline>opper<underline>o</underline>xidase (MCO) proteins possibly contributing to the total ferroxidase activity. Detailed characterisation of Fe-responsiveTaMCO3shows that it complements the yeast FET3 mutant and rescues the Fe-deficiency sensitivity phenotype ofArabidopsis atmco3mutants by enhancing vascular iron loading. Transgenic wheat lines overexpressing TaMCO3 exhibited increased root iron accumulation and improved tolerance to Fe deficiency by augmenting the expression of Fe-mobilizing genes. Our findings highlight the role of spatially resolved gene expression in Fe deficiency responses, suggesting strategies to reprogram cells for improved nutrient stress tolerance.