Research progresses on iron uptake, translocation and their signaling pathways in strategy I plants

Iron (Fe) is an essential microelement for plant growth and development, however, its bioavailability is severely limited in well-aerated or calcareous soils. As a result, Fe deficiency is often one of the key factors limiting the health growth and production of crops, and the strategyⅠplants are more likely to suffer Fe deficiency than the strategyⅡplants. Molecular breeding for improving Fe nutrition highly depends on the well understanding of the mechanisms of Fe uptake and utilization in strategyⅠplants. This paper reviewed firstly the activation of Fe in rhizosphere, its uptake by root cells and subsequent transportation in xylem and phloem, and reutilization of intra- and extra-cellular Fe in strategyⅠplants. Then the regulation mechanisms of Fe uptake, transportation and homeostasis in strategyⅠplants were focused, including the regulatory network of bHLH and MYB transcription factors, ubiquitination of proteins, and signaling transduction of small molecular weight chemicals. Finally, some unsolved questions and future researches were discussed.