POSITIVE REGULATOR OF IRON HOMEOSTASIS 1, OsPRI1, facilitates iron homeostasis ($)

Zhang et al. showed that POSITIVE REGULATOR OF IRON HOMEOSTASIS 1 (OsPRI1), a bHLH transcription factor, is an interacting partner of the iron-binding sensor OsHRZ1. A loss-of-function mutation of OsPRI1 is responsible for a hypersensitive response to Fe deficiency. OsPRI1 works downstream of OsHRZ1 and directly controls the expression of OsIRO2 and OsIRO3 by binding to the promoter regions. At the same time, the stability of OsPRI1 was negatively correlated with OsHRZ1 production, because OsPRI1 is subjected to ubiquitination by OsHRZ1. This study has provided a very important missing link (OsPRI1) between the iron-binding sensor OsHRZ1 and the Fe-deficiency–responsive genes OsIRO2 and OsIRO3 to define the OsHRZ1–OsPRI1–OsIRO2/3 signal transduction cascade in rice. Plant Physiol. 10.1104/pp.17.00794