The Anthropocene epoch is associated with the spreading of metals in the environment increasing oxidative and genotoxic stress on living organisms 1,2 . Once regarded as a curiosity, plants hyperaccumulating metals are now envisioned as an opportunity to remediate metal contaminated soils. About 500 plant species adapted to metalliferous soils acquired the capacity to hyperaccumulate (>0.1% of dry weight) nickel in their shoot 3 . The phylogenetic distribution of these hyperaccumulators in 50 families suggest that this complex trait evolved multiple times independently from basic mechanisms involved in metal homeostasis. However, the exact nature of these mechanisms and whether they are shared between various lineages is not known. Here, using cross-species transcriptomic analyses in different plant families, we have identified convergent functions that may represent major nodes in the evolution of nickel hyperaccumulation. In particular, our data point out that constitutive high expression of IREG/Ferroportin transporters recurrently emerged as a mechanism involved in nickel hyperaccumulation.Nickel hyperaccumulators are found worldwide as herbaceous plants, shrubs or trees growing on outcrops originating from ultramafic rocks, such as serpentine soils rich in iron, nickel, and cobalt. Although nickel hyperaccumulation is a rare and complex trait, it appeared independently in many distant plant families worldwide (Figure 1). In this study, we ask whether the same molecular mechanisms have been recruited convergently to reach this extreme trait. To address this question, we first compared the transcriptomes of nickel hyperaccumulators and closely related non-accumulator species to identify candidate genes involved in nickel hyperaccumulation. Then, in a second step, we established orthologous relationships to identify genes with similar functions that display differential expression in nickel hyperaccumulators from distant families.

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