Plant beneficial bacteria, defined as plant growth-promoting rhizobacteria (PGPR), play a crucial role in plants’ growth, stress tolerance and disease prevention. In association with the rhizosphere of plants, PGPR facilitate plant growth and development either directly or indirectly through multiple mechanisms, including increasing available mineral nutrients, moderating phytohormone levels and acting as biocontrol agents of phytopathogens. It is generally accepted that the effectiveness of PGPR inoculants is associated with their ability to colonize, survive and persist, as well as the complex network of interactions in the rhizosphere. Despite the promising plant growth promotion results commonly reported and mostly attributed to phytohormones or other organic compounds produced by PGPR inoculants, little information is available on the potential mechanisms underlying such positive effects via modifying rhizosphere microbial community and soil functionality. In this review, we overviewed the effects of PGPR inoculants on rhizosphere microbial ecology and soil function, hypothesizing that PGPR may indirectly promote plant growth and health via modifying the composition and functioning of rhizosphere microbial community, and highlighting the further directions for investigating the role of PGPR in rhizosphere from an ecological perspective.

Paving the Way From the Lab to the Field: Using Synthetic Microbial Consortia to Produce High-Quality Crops

As one of the most serious soil erosion areas in China, red sandstone erosion areas in southern China have been seriously affected by abundant annual rainfall. To understand the effects of AM fungi and different grass strips on soil erosion characteristics in red sandstone erosion areas in southern China, we selected Cynodon dactylon, Lotus corniculatus, Zoysia japonica, and Astragalus sinicus. Two treatments were carried out for each grass: AM was the soil in its original state, and CK was the soil in which the original AM fungi were eliminated. Taking CK treatment as the control group, any changes of runoff and sediment yield and nutrient loss under different grass strip conditions were measured. The total yield of runoff and sediment in the four grass strips under CK treatment was greater than that of AM. The runoff ammonium nitrogen loss concentration in AM treatment was smaller than in CK treatment under continuous scouring. The ammonium nitrogen loss concentration of sediment during continuous scouring showed a decreasing trend. Under AM treatment, the loss concentration of sediment ammonium nitrogen showed a decreasing trend compared with the CK treatment. The percentage of sediment particles >2 mm in the four grass strips was significantly larger for CK treatment than AM treatment (p < 0.05), and except for Cynodon dactylon, the percentage of sediment particles in the size range of 1–2 mm for other grass strips was significantly larger for CK treatment than for AM treatment (p < 0.05); the percentage of sediment particles at 0.02–0.25 mm was significantly smaller for CK treatment than for AM treatment (p < 0.05). The mean weight diameter (MWD) of sediments produced by the four grass strips under simulated scouring showed an overall increasing trend with increased scouring time. The mean weight diameter (MWD) of sediments produced under CK treatment was larger than that of AM treatment. The fractal dimension (D) of sediments showed a decreasing trend with increased scouring time. These results showed that AM fungi can promote the growth of plant roots, strengthen soil anchoring, protect large particle aggregates in soil under rainfall scouring, and reduce soil erosion and nutrient loss in red sandstone erosion areas in southern China. Cynodon dactylon and Zoysia japonica were more prominent than Lotus corniculatus and Astragalus sinicus in inhibiting soil erosion in red sandstone erosion areas.

This study aimed to characterize the spatial patterns of soil nutrients and labile carbon in the 0–20 cm surface layer of a red-soil bench-terrace hillslope during the first year following cut-and-fill engineering. Soil nutrient redistribution is classically conceptualized as upslope depletion and downslope enrichment, yet whether this paradigm holds after bench terracing remains poorly documente d. On a granite-derived red-soil hillslope in Yudu County, Jiangxi Province, China, we established three replicated transects across four slope positions in May 2025, one year after cut-and-fill bench terracing combined with Camellia oleifera–Pinus massoniana mixed young-forest restoration. The 0–20 cm surface layer was sampled for pH, organic matter, total nitrogen, total phosphorus, water-soluble organic carbon, particulate organic carbon (POC), and mechanical composition. The results showed that organic matter, total nitrogen, and POC all peaked on the upper slope, with enrichment factors of 8.8×, 3.8×, and 5.1× relative to the hilltop, respectively; the slope base did not function as a nutrient sink. Texture displayed a monotonic downslope differentiation but decoupled from the nutrient gradient, and pH was significantly negatively correlated with organic matter and POC. The observed short-term post-restoration non-classical pattern is best interpreted as the spatially heterogeneous footprint of subsurface exposure and localized topsoil redistribution during cut-and-fill engineering, overlain by one year of incipient biological input, rather than the product of modified erosion–deposition dynamics. POC appears to be a particularly sensitive tracer of early biological activity under these short-term post-restoration conditions when superimposed on a depleted inverted-surface baseline, and the pronounced spatial heterogeneity implies that precision management based on high-resolution spatial diagnosis is warranted to address the substrate patchiness inherited from cut-and-fill operations. However, the temporal scope of this one-year baseline survey limits the inference of long-term indicator performance, and follow-up monitoring is needed to confirm whether POC retains this sensitivity as the surface layer matures.

The intensive management of orchards is posing substantial pressure to the surrounding environments, threatening the fruit quality and sustainable development of fruit industry. Arbuscular mycorrhiza (AM) is ubiquitous in soil established with arbuscular mycorrhizal fungi colonizing roots of host plants. AM connects the roots, bacteria and soil, enhancing the interactions between plants and soil microbiome, augmenting the nutrient uptake of plants, improving fitness in facing abiotic and biotic stresses, and strengthening the soil structure and function. Thus, AM is considered as an important grasp to improve the clean production, and an alternative for the shift from intensive to organic management in orchards. Our study showed that the disappearance or reduction of AM fungi community, in accordance with strong soil erosion and the losses of phosphorus. The practices, such as sod culture in orchards or inoculating with AM fungi, is beneficial to the recovery of AM fungi community. More suitable measures aiming at optimize the AM fungi community are being developed and extended in subtropical orchards. Collectively, the regulation of AM fungi community can be a significant way to improve the degree of clean productions of subtropical orchards.