Gene networks involved in iron acquisition strategies in plants

Iron uptake is strictly controlled in all organisms. Iron deficiency induces a well-defined series of physiological events, either based on iron reduction ( strategy I, dicots and monots except grasses) or iron chelation ( strategy II, grasses). Genes encoding the structural components of the strategies I and II have been described recently using molecular, genetic and biochemical techniques. The major participants of the strategy I are the ferric reductase and the Fe II transporter encoded by Atfro2 and Atirt1 homologs, respectively. The strategy II comprises the enzymes for phytosiderophore biosynthesis encoded by the genes for nicotianamine synthase, nicotianamine aminotransferase and others. Transcriptional and post-transcriptional regulatory mechanisms control the strategy I and II genes. The tomato fer gene is among the first identified regulator genes for iron uptake. The identification and characterisation of the regulatory mechanisms is an important step towards designing new strategies for improving the iron content of crop plants for human health.