Xiao et al. at Beijing (pp. 881–889), focusing on a strongly cold-tolerant apple species, Malus baccata, widely used as a rootstock in north China. Iron deficiency is a widespread problem, especially for trees grown on calcareous soils. The authors have therefore investigated at the molecular genetic level the trafficking of Fe together with Mn and Cd. NRAMPS (natural resistance-associated macrophage proteins) are highly conserved proteins, present in both prokaryotes and eukaryotes, that are implicated in the transport of metal ions. Based on sequence data from NRAMPS in different plant species, the authors have used RT–PCR and RACE to isolate a full-length cDNA encoding an NRAMP protein in M. baccata. Southern blotting showed that the MbNRAMP1 gene exists as a single copy in the M. baccata genome. The gene was most strongly expressed in roots and the level of expression increased under Fe deficiency, as indicated by northern blots. A direct demonstration of the role of MbNRAMP1 in trafficking of metal ions was achieved by transferring the gene into yeast mutants deficient for Fe and Mn uptake. Both strains were rescued by the MbNRAMP1 gene, indicating that uptake of both ions had been restored. Expression of MbNRAMP1 also increased Cd uptake in yeast, rendering the cells more sensitive to Cd toxicity. As in M. baccata itself, expression was strongly influenced by iron status. Further, evidence obtained with GFP-tagged MbNRAMP protein suggests that yeast cells can also regulate the subcellular location of the protein in response to changes in iron status.