부산대학교 도서관

Background and aims: Iron (Fe) plaque which normally coats rice roots has a strong affinity for phosphorus (P), with a debated effect on plant P uptake. Furthermore, plant responses to P availability shape the rhizospheric environment, possibly affecting the rates of Fe plaque formation and dissolution. The role of Fe plaque to serve as a sink or source of available P may depend on root traits, themselves influenced by P availability. However, the underlying mechanism regulating these interactions remains unclear. In this study, we investigated the effects of P availability on root traits, Fe plaque dynamics and their implications for P uptake and rice plant growth.Methods: Plants were hydroponically grown for 60 days under P-sufficiency or P-deficiency, with or without Fe plaque. Root traits, rhizosphere acidification, and the rates of Fe plaque formation and dissolution were investigated and linked to differences in rice P content and growth.Results: P-deficient conditions stimulated root development and promoted Fe plaque formation on the root surface compared to P-sufficient conditions. However, P limited plants exhibited a faster Fe plaque dissolution, along with increased net proton exudation. After 60 d, P-deficient plants showed higher P uptake in the presence of Fe plaque, whereas the opposite was observed in P-sufficient plants, where Fe plaque limited plant P uptake.Conclusions: The role of Fe plaque in regulating P uptake highly depends on the dynamic nature of this Fe pool that is strictly linked to P availability and regulated by plant responses to P deficiency.