A large proportion of the nitrate (NO₃⁻) acquired by plants from soil is actively transported via members of the NRT families of NO₃⁻ transporters. In Arabidopsis, the NRT1 family has eight functionally characterised members and predominantly comprises low-affinity transporters; the NRT2 family contains seven members which appear to be high-affinity transporters; and there are two NRT3 (NAR2) family members which are known to participate in high-affinity transport. A modified reciprocal best hit (RBH) approach was used to identify putative orthologues of the Arabidopsis NRT genes in the four fully sequenced grass genomes (maize, rice, sorghum, Brachypodium). We also included the poplar genome in our analysis to establish whether differences between Arabidopsis and the grasses may be generally applicable to monocots and dicots. Our analysis reveals fundamental differences between Arabidopsis and the grass species in the gene number and family structure of all three families of NRT transporters. All grass species possessed additional NRT1.1 orthologues and appear to lack NRT1.6/NRT1.7 orthologues. There is significant separation in the NRT2 phylogenetic tree between NRT2 genes from dicots and grass species. This indicates that determination of function of NRT2 genes in grass species will not be possible in cereals based simply on sequence homology to functionally characterised Arabidopsis NRT2 genes and that proper functional analysis will be required. Arabidopsis has a unique NRT3.2 gene which may be a fusion of the NRT3.1 and NRT3.2 genes present in all other species examined here. This work provides a framework for future analysis of NO₃⁻ transporters and NO₃⁻ transport in grass crop species.

• Background and Aims The amount of iron (Fe) and copper (Cu) that is loaded into grains of wheat (Triticum aestivum) depends on both the amount of nutrient taken up by the plant post-anthesis and the amount that is remobilized from vegetative organs as they senesce. Previous reports have shown that these two micronutrients behave quite differently in wheat in that Cu is readily remobilized to the grain whilst Fe shows poor remobilization. The object was to quantify the distribution of Fe and Cu in wheat and to show how this distribution changes from anthesis to grain maturity. • Methods The uptake and distribution of both Fe and Cu were investigated in wheat grown at two levels, adequate and low, of both micronutrients. Plants were grown in sand culture and the main culms were harvested at anthesis, 18 days post-anthesis and at maturity. Plants were separated into various organs and analysed for Fe and Cu using ICP-OES. • Key Results There was good remobilization of Fe from the rest of the shoot to the grain with 77 % of the total shoot Fe in the grain at maturity. In the adequate-Cu treatment there was 62 % of the total plant Cu in the grain at maturity, whereas in the low-Cu treatment this was only 40 %. There was no net Fe taken up into the above-ground plant parts post-anthesis whilst for Cu there was. The remobilization evident for Fe and Cu was greater than that found for zinc and much greater than evident for manganese in the same material. • Conclusions The results reported here represent good evidence for the high reproductive mobility of both Fe and Cu in wheat.