Research progress on rhizosphere remediation of soil pollution

Soil pollution poses significant challenges to both the ecological safety of agricultural land and human health. In recent years, rhizosphere remediation has emerged as a promising bioremediation technology, characterized by its green, safe, and environmentally friendly. The unique biochemical and microbiological properties of the rhizosphere microenvironment indicate that rhizosphere remediation possesses considerable potential for the remediation of soil pollution. The article offered a comprehensive review of the latest research trends and current applications of rhizosphere remediation technology in the field of soil pollution mitigation. The mechanisms of rhizoremediation were discussed from three distinct perspectives: root exudates, iron plaques on root surfaces, and rhizosphere microorganisms. The root system can achieve the adsorption, fixation, degradation and transformation of pollutants through releasing root exudates and forming iron plaque, making it an indispensable natural driving force in the process of soil pollution remediation. The root exudates can promote the remediation of contaminated soil mainly by altering the physicochemical properties of the soil, regulating the structure of rhizosphere microbial communities, and promoting plant growth. The unique structural characteristics of iron plaques on root surfaces can enhance the absorption of nutrient elements by plants, improve plant stress resistance, and influence the transformation and transport of pollutants. Rhizosphere microorganisms, as the core of fundamental remediation, can promote the degradation, transformation, and fixation of pollutants through their physiological and biochemical effects. Furthermore, they can reduce the bioavailability of pollutants and alleviate the stress on plants by secreting active substances. To understand the mechanism of rhizosphere remediation more comprehensively, the response mechanism of rhizosphere microorganisms to pollution and the factors influencing these responses were analyzed. Depending on the nature of the pollutants, the abundance of tolerant and degrading microbial strains increased, leading to the formation of unique microbial community structures to cope with polluted environments. Additionally, different plant species, genotypes, and root ecological niches can influence the structure of rhizosphere microbial communities as well as the absorption and accumulation of pollutants. It has been proposed that the rhizosphere effect can be enhanced through the introduction of exogenous substances, modification of plant cultivation patterns, and the application of electric fields, thereby improving the effectiveness of soil pollution remediation. At the same time, to accurately evaluate the level of soil pollution and remediation effects, reveal the molecular biological processes involved, and achieve precise remediation, future research should focus more on the construction of a root exudates indicator system under contaminated conditions, the in-depth exploration of the micro-mechanisms of rhizosphere remediation, and the combination with emerging technologies such as machine learning. This article provides a valuable reference and insight for research on soil pollution remediation technologies through a detailed review of the existing studies in this field.