Metagenomic insights into the influence of rhizosphere microbiome functional profiles for soil phosphorus mobilization under Pseudomonas combinations and phosphate addition

The application of Pseudomonas combinations is a key strategy to enhance plant uptake of phosphorus (P). However, it remains unclear whether different phosphate inputs can enhance the interaction between Pseudomonas and the rhizosphere soil microbiome to influence soil P mobilization. In this study, we examined the effects of Pseudomonas inoculation and P treatments (no addition, dipotassium hydrogen phosphate or sodium phytate addition) on soil P mobilization and explored the microbiome functional profiles for P cycling in the alfalfa rhizosphere using metagenomic sequencing. The results indicated that the sodium phytate addition significantly increased bacterial network complexity, and the core microbial genera in the rhizosphere of alfalfa under inoculation treatments were Pseudomonas and Nitrospira , which significantly positively correlated with soil microbial biomass phosphorus (MBP) content and acid phosphatase activity. Meanwhile, P addition increased the abundance of gcd and phy genes, and their abundance was positively regulated by Pseudomonas and Nitrospira . Besides, P addition exerted a positive effect on plant growth and P accumulation by increasing soil available P and MBP contents. Taken together, the direct impact of P addition on soil P content and the indirect effect of Pseudomonas inoculation on the structure and function of alfalfa rhizosphere microbial communities jointly drive the transformation of soil phosphate into plant-available forms, with sodium phytate addition showing stronger interactive effects and microbial activities that promote alfalfa growth. Our findings confirm the potential of phytate as an organic fertilizer input, which is beneficial for the establishment of efficient P management strategies in sustainable agricultural ecosystems.