Generation Of Iron-Deficiency Tolerant Rice By Overexpressing A Transcription Factor OsIRO2 Which Regulates The Genes Involved In Iron Acquisition.

Abstract

Iron is essential for most living organisms and is often the major limiting nutrient for normal growth. Graminaceous plants secrete mugineic acids phytosiderophores (MAs) to rhizosphere to solubilize and absorb rhizospheric iron. We reported that the iron-deficiency inducible bHLH transcription factor OsIRO2 is responsible for the regulations of the genes involved in Fe absorption, such as genes involved in MAs synthesis and iron transport (Ogo et al., 2007 Plant J.). Here, we successfully demonstrated that OsIRO2 overexpression improved tolerance of rice to iron deficiency on calcareous soils, as a result of activating the expressions of several genes involved in iron uptake in rice. In addition to increased iron content in shoots, OsIRO2 overexpression rice accumulated higher amount of iron in seeds than that of non-transformant when grown on calcareous soil. The OsIRO2 overexpression improved both absorption and translocation of iron in rice under low iron-availability.