TpIRT1 is a transition metal transporter in Polish Wheat (Triticum polonicum L.) with a broad substrate specificity

Aims: (1) Explore the metal substrate specificity of homologous TpIRT1A and TpIRT1B transporters from dwarf Polish wheat by expressing them in protoplast, yeast, and transgenic Arabidopsis ; (2) screen polymorphic residues of IRT1 homologs from tetraploid and diploid ancestral wheat species that change the substrate specificity. Methods: Two IRT1 homoeologs were isolated from A ( TpIRT1A ) and B ( TpIRT1B ) genomes of a tetraploid crop, polish wheat ( Triticum polonicum ). Both of them were analysed by expressing them in yeast and Arabidopsis protoplast, respectively. Then we constructed over-expressing transgenic plants of TpIRT1B for metals property analysis in Arabidopsis. We also isolated 22 IRT1 homoeologs from tetraploid and diploid ancestral wheat species and expressed them in yeast for function analysis. Results: Our data highlighted the importance of TpIRT1 in the uptake and translocation of Fe, Mn, Co, and Cd with direct implications for wheat yield potential. Both TpIRT1A and TpIRT1B were located at the plasma membrane and internal vesicles in Arabidopsis protoplasts, and responsible for Cd and Co sensitivity in yeast. The over-expression of TpIRT1B in A. thaliana increased Fe, Mn, Co, and Cd concentration in its tissues and improved plant growth under Fe, Mn, and Co deficiencies, while causing more sensitivity to Cd than wild-type plant. Functional analysis of IRT1 homoeologs from tetraploid and diploid ancestral wheat species in yeast disclosed four distinct amino acid residues in TdiIRT1B ( T. dicoccum ) and TtuIRT1B ( T. turgidum ). Altogether, these results increase the knowledge of IRT1 function in a global crop, wheat.