H2O2-mediated oxidation of PHOSPHATE STARVATION RESPONSE2 promotes adaptation to low phosphate in rice

Phosphorus (P) is an essential macro-nutrient for plant growth and development. It is preferentially taken as inorganic phosphate (Pi). Plants have evolved elaborate mechanisms to adapt to low Pi (LP) stress through activating Pi-starvation responses. H2O2 is an important signal molecule involved in plant adaptation to diverse environmental stresses. However, whether H2O2 plays a role in Pi-starvation responses remains unknown. Here, we reveal that H2O2 produced by the respiratory burst oxidase homologs OsRBOH-D/H facilitates phosphate uptake and utilization under LP conditions in rice. Mechanistically LP-induced H2O2 promotes the oxidization of the key phosphate signaling transcription factor PHOSPHATE STARVATION RESPONSE2 (OsPHR2) at its Cys377 residue to trigger its oligomerization, sequence-specific DNA binding ability, and nuclear translocation, thereby activating Pi-starvation responses to adapt to LP conditions. Additionally, our molecular and biochemical data revealed that OsRBOH-D is a direct target gene of OsPHR2. Thus, OsPHR2 and OsRBOH-D form a positive feedback regulatory loop in which H2O2 acts as a second messenger to amplify the Pi-starvation response. Phosphorus is an essential plant nutrient. Here Meng et al. show that low phosphorus availability stimulates hydrogen peroxide production which in turn promotes the oligomerization, nuclear translocation and DNA binding activity of the PHR2 transcription factor and enhances the phosphate starvation response.