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

Abstract

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.

Stable Isotope Analyses Reveal Impact of Fe and Zn on Cd Uptake and Translocation by Theobroma cacao

“…This similar magnitude of fractionation in all treatments suggests that while total Cd uptake can differ between cacao plants grown under different conditions, they appear to use the same dominant uptake mechanism(s). This may be associated with Fe and Cd sharing common membrane transporter proteins [ 41 , 45 , 79 , 80 ]. The expression of a cacao gene ( TcNRAMP5 ) that encodes one such protein, NRAMP5, has been found to be reduced under Fe-sufficient conditions and Cd supplementation, compared to nutrient-deficient and low-Cd conditions [ 80 ].…”

“…It has been shown (e.g., for rice, wheat, and poplar) that low Fe availability enhances plant uptake of Cd [ 40 , 41 ], while high Fe levels in soils and in foliar treatments can reduce Cd uptake [ 42 , 43 , 44 ]. This is at least partly due to the regulation of Fe supply by the IRT1 (Iron Regulation Transporter 1) gene, which has also been found to mediate the levels of Cd [ 1 , 45 , 46 ].…”