Root Iron Plaque: A natural Barrier and Potential Risk for Rice against Heavy Metal Pollution

Root iron plaque is a colloidal film of iron-manganese oxides formed on the root surface of rice. Its formation process involves oxygen released by rice roots oxidizing Fe²⁺ to Fe³⁺, which then combines with elements such as manganese to form precipitates that ultimately cover the surfaces of root tips and root hairs. With a large specific surface area and abundant functional groups, iron plaque can regulate the migration and accumulation of heavy metals through processes like adsorption and coprecipitation, serving as a "natural barrier" against heavy metal pollution. This paper systematically elaborates on the external resistance and internal tolerance mechanisms of plants to heavy metals mediated by iron plaque, and analyzes the effects of factors such as water management, fertilization methods, root aeration capacity, and soil microorganisms on the formation of iron plaque as well as the migration and accumulation of heavy metals. In addition, this paper also summarizes the potential risks of iron plaque in practical applications and prospects future research directions.