Abstract:
Fe Transporter 1 (FTR1), a high-affinity iron permease, facilitates the uptake of ferric ion (Fe
3+) into cells. This study investigated the
FTR1 gene family in the early terrestrial plant
Physcomitrium patens (Hedw.) Mitt., integrating genome-wide identification, sequence analysis, evolutionary inference, subcellular localization, and expression profiling under iron stress. Three members of the
PpFTR1 gene family (
PpFTR1-1,
PpFTR1-2, and
PpFTR1-3) were mapped to chromosomes 15, 21, and 22, respectively. All three genes encoded proteins that contained the conserved REXXE Fe-binding motif; however, the second REXXE motif in the PpFTR1-3 protein was mutated. Bioinformatics analysis and protein subcellular localization experiments indicated that all three transmembrane proteins localized to the cell membrane. The
PpFTR1-1 and
PpFTR1-2 genes were significantly upregulated in response to both iron deficiency and iron excess, whereas
PpFTR1-3 remained unresponsive. Phylogenetic analysis revealed that the
FTR1 family is predominantly distributed in green algae, charophytes, and early terrestrial plants (e.g., mosses and ferns), with homologous
FTR1 sequences entirely absent in seed plants. Notably,
FTR1 sequences from early terrestrial plants exhibited closer evolutionary affinity to fungal homologs than to those of charophytes, the ancestral lineage of terrestrial plants, indicating a possible horizontal gene transfer event during terrestrialization. These findings not only provide a theoretical framework for understanding the molecular mechanisms by which early land plants adapted to iron stress but also offer insights into gene regulation mechanisms and the enhancement of iron uptake in crops.