Identification of new hardy ferns that preferentially accumulate light rare earth elements: a conserved trait within fern species

Abstract

Environmental contextRare earth elements (REEs) are strategic metals and emerging contaminants for which plant-based remediation measures are needed. We screened a collection of hardy ferns and identified new accumulator species that preferentially transferred light REEs to their fronds. This study is an important step towards understanding the mechanisms of REE accumulation in plants. AbstractRare earth elements (REEs) include the lanthanides plus yttrium and scandium, and can be split according to their atomic mass into light (LREEs) and heavy REEs (HREEs). The increasing demand for REEs is mainly driven by new technologies, and their current low recyclability has led them to become emerging contaminants. The identification of new REE accumulators may help in determining the REE transfer mechanisms and may result in interesting candidates for phytoremediation techniques. To that end, a collection of 49 hardy fern species, grown in REE-spiked substrate, were screened for their potential in REE accumulation. REE concentrations were very low in the fronds of all Polypodium species, whereas all Athyrium species highly accumulated REEs. The REE accumulation level was more variable among the different species of Dryopteris, Blechnum, Woodwardia, Cystopteris and Polystichum. However, whatever the species, LREEs were preferentially transferred to the fronds over HREEs. This conserved trait was independent of the availability of different REEs in the substrate and instead may arise from specific transfer systems in ferns for the two groups of REEs. Furthermore, REE accumulation was correlated to Ca and Al, which suggested the existence of common uptake pathways. Altogether, these results are of great interest for phytoremediation purposes since appropriate species can be chosen according to the area to be remediated, and they also provide new insights into a more in-depth characterisation of the underlying REE accumulation mechanisms in ferns.

Combined omics approaches reveal distinct responses between light and heavy rare earth elements in Saccharomyces cerevisiae

“…For instance, plants that accumulate REEs display specific enrichment of either LREEs or HREEs (Grosjean et al, 2020(Grosjean et al, , 2019. Taken together, these few available studies support the need to elucidate the cellular and molecular mechanisms involved in the response to REEs, similar to work performed on the specific REE yttrium (Grosjean et al, 2018).…”

The Role of Microorganisms in Mobilization and Phytoextraction of Rare Earth Elements: A Review

“…RE mobilization is positively correlated with that of Fe and Mn (Cao et al, 2001). Due to their higher mobility in soils, LRE are more easily absorbed and accumulated by plants than heavy RE since the latter form much more stable complexes in soil solution (Brioschi et al, 2013;Grosjean et al, 2020). Indeed, roots preferentially absorb free ions rather than dissolved complexes (Brioschi et al, 2013).…”

“…A recent study identified new accumulating species RE using a screening method for ferns grown on RE contaminated substrate. Three species reached more than 200 mg/kg: Onoclea sensibilis, Athyrium othophorum and Athyrium filix-femina (Grosjean et al, 2020).…”

Genome-Wide Mutant Screening in Yeast Reveals that the Cell Wall is a First Shield to Discriminate Light From Heavy Lanthanides

“…In addition to their different toxicity levels (HREEs > LREEs ( Tyler, 2004 ; Gonzalez et al, 2014 ; Goecke et al, 2017 )), only a few studies revealed the specific modes of action of these two REE groups with a single multi-scale analysis directly comparing the differential effect of two Ln ( Grosjean et al, 2021 ). As such, specific accumulation of LREEs has been reported in ferns ( Grosjean et al, 2020 ), while angiosperms preferentially translocate HREEs in their aboveground tissues ( Liu et al, 2018 ; Grosjean et al, 2019 ), thereby suggesting different transport systems between LREEs and HREEs. Molecular evidence also supports this hypothesis in S accharomyces cerevisiae , in which disruption of the Ca channel Cch1p/Mid1p restricts La but not Gd uptake ( Ene et al, 2015 ).…”