Maize recruits beneficial microorganisms via rhizosphere metabolites as signals to construct a functional network for saline-alkaline stress resistance.

Introduction: Carbonate-type saline-alkaline stress severely constrains maize production; however, the synergistic response mechanisms between rhizosphere microorganisms and metabolites remain unclear. Methods: Through field experiments along with the integration of soil chemical factor analysis, microbial high-throughput sequencing, and non-targeted metabolomics, we systematically investigated the response mechanisms of the rhizosphere microecosystem to saline-alkaline stress in maize fields in the carbonate chernozem region of the Songnen Plain, Northeast China. Results and discussion: Saline-alkaline stress significantly increased soil pH and electrical conductivity (EC) and decreased soil organic matter (SOM), total nitrogen (TN), and total phosphorus (TP) content. However, the rhizosphere exhibited buffering capacity and maintained a high cation exchange capacity (CEC). Microbial community analysis revealed that bacterial alpha diversity increased under stressful conditions. Contrarily, fungal diversity significantly decreased, and the community structure shifted towards a pathogen-dominated community, primarily within Ascomycota, particularly in the genus