Overexpression of OsIRO2 improves both iron uptake and translocation to seeds in rice
Iron deficiency is a worldwide agricultural problem on calcareous soils with low iron (Fe) availability and also poses a major human nutritional problem. Plants induce Fe-acquisition systems under conditions of low Fe availability. Previously, we reported that an Fe deficiency-inducible bHLH transcription factor, OsIRO2, is responsible for regulating the genes involved in Fe homeostasis in rice. Here, we show that OsIRO2 overexpression results in improved tolerance to low Fe availability in calcareous soil. In addition to increased Fe content in shoots, rice overexpressing OsIRO2 accumulates more Fe in seeds than non-transformant rice when grown on calcareous soil. OsIRO2 promoter–GUS analysis revealed that OsIRO2 expression could be detected in developing seeds. These results suggest that OsIRO2 plays a crucial role in regulating both Fe uptake from soil and Fe translocation to grain. Improved uptake and translocation of Fe in the OsIRO2-overexpressing rice under low Fe availability provides an approach for producing graminaceous crops that are tolerant to Fe deficiency and have Fe-rich seeds to enhance production and the nutritional quality of food.