Abstract
The root iron plaque is a film of iron-manganese oxide coatings formed on the surface of submerged plant roots. It results from root radial oxygen loss, which oxidizes Fe(II) to Fe(III) and combines with elements such as manganese, ultimately covering the root tips and root hair surfaces. Owing to its large specific surface area and abundant functional groups, the iron plaque can regulate the migration and accumulation of heavy metals through adsorption, co-precipitation, and other mechanisms, serving as a natural barrier against heavy metal pollution. This article systematically reviews the barrier mechanisms at the root surface and the internal adaptation mechanisms of the iron plaque in regulating the transport and accumulation of heavy metals in the plant-soil system. It also analyzes the influence of agronomic measures (such as water management and fertilization methods), the rhizosphere microenvironment (including root exudates and microbial communities), and root-related genes (such as Radial oxygen loss (ROL) related genes and iron-regulated transporters) on the formation of the iron plaque and its effects on heavy metal migration and accumulation. Furthermore, potential risks associated with the iron plaque in the plant-soil system are discussed, and future research directions are proposed.