Screening for the next generation heavy metal hyperaccumulators for dryland decontamination

• We discover a new plant species Alcea aucheri with promising potential as lead hyperaccumulator in drylands.
• Alcea aucheri showed a unique combination of high lead shoot accumulation, translocation factor, enrichment Coefficient and Biomass.
• We estimate that Alcea could result in a remediation of 204.12 kg ha−1 Pb and 37.80 kg ha−1 Cd from soil in a 48 days period.

Heavy metal removal by plants bears a great potential to decontaminate soils. A major challenge remains to find plant species that accumulate heavy metal, harbor a sufficient biomass and grow in the desired environmental conditions. Here we present candidate plants for phytoremediation in arid climates. We sampled sixteen dominant plants from mining area naturally polluted with high Pb-Zn and Cd concentration. Plants were assessed for their ability to accumulate Zn, Pb and Cd and six species were selected on the base of their heavy metal concentration in shoots and leaves, enrichment coefficient and translocation factor. Out of all the tested species in field study, Alcea aucheri was the most promising one which accumulated over than 460 and 4089 μg/g Pb in the roots and shoots, respectively. We confirmed this ability with a greenhouse experiment on soil spiked with different Pb and Cd concentrations. Concentration of Pb and Cd in aerial parts of A. aucheri were more than 1700 and 345 μg/g in 2400 and 200 mg/kg Pb and Cd soil treatment respectively. We propose that A. aucheri as model hyperaccumulator able to live in adverse condition, producing high biomass, and supersede heavy metal accumulation reported to other plants, making of this species one of the best Pb hyperaccumulator reported to date.

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