Heavy metal contamination is one of the main factors causing ecological and environmental degradation. Soil contamination by heavy metals decreases soil quality, reduces agricultural productivity and quality, and even threatens human health. Therefore, optimizing remediation strategies for soils polluted with heavy metals is of great significance for high-yield, good-quality, and sustainable agriculture. Numerous domestic and foreign scholars have carried out a large number of studies on the phytoremediation of heavy metal contaminated soils. However, the remediation efficiency may be restricted by soil and climatic/environmental conditions. The synergistic remediation of microorganisms and plants is considered an effective means to improve metal remediation efficiency under environmental stresses. Metal-resistant plant growth-promoting bacteria (PGPB) not only promote plant growth and its resistance to biotic (e.g., phytopathogens, etc.) and abiotic (e.g., drought, salinity, extreme temperatures, heavy metals, etc.) stresses but also alter meal bioavailability in soils and metal toxicity in plants, thereby improving phytoremediation efficiency. In this paper, the mechanisms involved in promoting plant growth and its stress tolerance, and affecting metal bioavailability by metal-resistant PGPB, were systematically summarized. Furthermore, research progress on the application of PGPB in ecological restoration in recent years was extensively reviewed.
Keywords: abiotic stress; bioremediation; growth promoting mechanism; heavy metal bioavailability; plant growth-promoting bacteria (PGPB).