[Application potential of siderophore-producing rhizobacteria in phytoremediation of heavy metals-contaminated soils: a review].

Siderophore-producing rhizobacteria (SPR) are a group of plant growth-promoting rhizobacteria, being able to play an important role in assisting the phytoremediation of heavy metals-contaminated soils. Based on the comprehensive analysis of related researches at home and abroad, this paper elaborated the functions of SPR in alleviating the heavy metals stress and toxicity to plants and the mechanisms of SPR in improving the heavy metals bioavailability in soil, and indicated that SPR had good application potential in promoting the plant growth in heavy metals-contaminated soils and reinforcing the heavy metals accumulation in plants. The contradictory phenomena of SPR in increasing or decreasing heavy metals accumulation in plants, which existed in current researches, were also analyzed. Aiming at the deficiencies in current researches, it was suggested that in the future researches, the mechanisms of the interactions between SPR and plants, especially hyperaccumulators, should be further studied, the key factors affecting the heavy metals complexation and mobilization in soil by siderophores should also be further clarified, the effects of siderophores on the heavy metals bioavailability and its subsequent influence on the heavy metals uptake by plants should be comprehensively considered, and the measures for improving the colonization of SPR in heavy metals-contaminated soil should be explored.