Sequence analysis and expression of the IRT1 gene under iron deficiency in amaranth (Amaranthus mangostanus L.)

Abstract

Abstract Aims Amaranth (Amaranthus mangostanus L.) is a hyperaccumulator that is effective in remediating soil cadmium (Cd) pollution. The iron-regulated transporter 1 (IRT1) gene, which encodes the iron (Fe) transporter protein, plays a crucial role in Cd uptake in plants, and its expression is induced by Fe deficiency. But its role in amaranth remains unknown. Methods In this study, the IRT1 gene from amaranth was cloned for sequence analysis and functional prediction using bioinformatics methods. A hydroponic experiment was performed to study amaranth Cd uptake and its expression under Fe deficiency with treatments of + Fe, −Fe, + Fe + Cd, and − Fe + Cd. Results A partial AmIRT1 cDNA sequence encoding 185 amino acids was obtained. Protein structure prediction revealed with almost the entire Pfam ZIP functional domain within the sequence. Functional prediction indicated that the protein was a transmembrane (TM) ion transporter with three TM domains. Using homology comparison and phylogenetic tree analysis, we found that the AmIRT1-encoded protein showed the highest homology with Arabidopsis IRT proteins and clustered with IRT proteins from other plants. The shoot and root Cd concentrations increased by 9.6% and 10.9%, respectively, in − Fe treatment compared with + Fe treatment. Cd accumulation was also observed to increase. Notably, AmIRT1 gene expression increased under both − Fe and − Fe + Cd treatments, but did not change under + Fe and + Fe + Cd treatments. Conclusions The structure and properties of the AmIRT1-encoded protein were similar to those of ZIP family members in other plants. Its expression can be increased by regulating Fe nutrition to improve amaranth Cd uptake.