Plasma-Membrane-Localized Transporter NREET1 is Responsible for Rare Earth Element Uptake in Hyperaccumulator Dicranopteris linearis

Rare earth elements (REEs) are critical for numerous modern technologies, and demand is increasing globally; however,production steps are resource-intensive and environmentally damaging.Some plant species are able to hyper accumulate REEs, and understanding the biology behind this phenomenon could play a pivotal role in developing more environmentally friendly REE recovery technologies. Here, we identified a REE transporter NRAMP REE Transporter 1 (NREET1)from the REE hyper accumulator fern Dicranopteris linearis. AlthoughNREET1 belongs to the natural resistance-associated macrophage protein(NRAMP) family, it shares a low similarity with other NRAMP members.When expressed in yeast, NREET1 exhibited REE transport capacity, but itcould not transport divalent metals, such as zinc, nickel, manganese, or iron.NREET1 is mainly expressed in D. linearis roots and predominantly localized in the plasma membrane. Expression studies in Arabidopsis thaliana revealed that NREET1 functions as a transporter mediating REE uptake and transfer from root cell walls into the cytoplasm. Moreover, NREET1 has a higher affinity for transporting light REEs compared to heavy REEs, which is consistent to the preferential enrichment of light REEs in field-grown D. linearis. We therefore conclude that NREET1 may play an important role in the uptake and consequently hyper accumulation of REEs in D.linearis. These findings lay the foundation for the use of synthetic biology techniques to design and produce sustainable, plant-based REE recovery systems.