The two copies of the zinc and cadmiumZIP6transporter ofArabidopsis hallerihave distinct effects on cadmium tolerance

Plants have the ability to colonize highly diverse environments. The zinc and cadmium hyperaccumulatorArabidopsis hallerihas adapted to establish populations on soils covering an extreme range of metal availabilities. TheA. halleri ZIP6gene presents several hallmarks of hyperaccumulation candidate genes: it is constitutively highly expressed in roots and shoots and is associated with a zinc accumulation quantitative trait locus. Here, we show thatAhZIP6is duplicated in theA. hallerigenome. The two copies are expressed mainly in the vasculature in bothA. halleriandArabidopsis thaliana, indicative of conservedcisregulation, and acquired partial organ specialization. Yeast complementation assays determined that AhZIP6 is a zinc and cadmium transporter.AhZIP6silencing inA. hallerior expression inA. thalianaalters cadmium tolerance, but has no impact on zinc and cadmium accumulation.AhZIP6-silenced plants display reduced cadmium uptake upon short-term exposure, adding AhZIP6 to the limited number of Cd transporters supported byin plantaevidence. Altogether, our data suggest that AhZIP6 is key to fine-tune metal homeostasis in specific cell types. This study additionally highlights the distinct fates of duplicated genes inA. halleri.