Phosphorus fertilizer forms orchestrate contrasting plant–microbe recruitment strategies in the rhizosphere of field grown wheat

Plants engage in intricate interactions with rhizosphere microbes. These interactions are crucial for plant nutrient acquisition and productivity, but the mechanisms by which different nutrient forms shape rhizosphere microbes to enhance nutrient utilization under field conditions remain unclear. We investigated the rhizosphere bacterial communities of wheat and their functions across key growth stages in response to different phosphorus (P) fertilizer forms in a 4-yr field experiment, integrating 16S rRNA gene sequencing, metatranscriptomic sequencing, and soil chemical analyses. In the field, the three P fertilizer forms showed comparable P use efficiency (PUE) over 4 years. At the three-leaf stage, insoluble P fertilizer increased root-associated citrate concentrations, enriched carboxylate-associated bacteria (e.g. Bacillus, Solirubrobacter, and Nitrospira), and resulted in higher transcript abundance of genes involved in citrate metabolism and P acquisition. Polymeric P fertilizer enhanced soil phosphatase activity, increased root-associated succinate concentrations, and had higher transcript abundance of genes involved in succinate metabolism and complex polysaccharide degradation. Soluble P fertilizer increased soil available P and enriched Devosia, favored glycoprotein degradation, while showing a limited response to P mobilization processes. This study suggests that, under field conditions, different P fertilizer forms shape distinct rhizosphere bacterial communities to improve PUE by altering root-associated carboxylate release.