show Abstracthide AbstractWe compare global gene expression patterns between the two metal hyperaccumulator plants: Noccaea japonica, originating from nickel-rich serpentine soils, and Noccaea caerulescens (ecotype Ganges), origination from zinc/lead-mine soils, under excess nickel conditions. There were significant differences in the expression levels of genes involved in mineral transport, mineral homeostasis, and metal tolerance. Expression level of iron-regulated transporter 1 (IRT1), encoding the primary iron uptake transporter and also causing excess nickel absorption in Arabidopsis thaliana, is higher in N. japonica than in N. caerulescens, but NjIRT1 has a point mutation at the Asp-100, which is essential for iron transport, suggesting that NjIRT1 misses its transport functions for iron and possibly nickel.