Synergy between silicon and beneficial microorganisms enhances plant abiotic stress tolerance through rhizosphere restructuring and coordinated defense.

Abiotic stress is a major factor limiting crop productivity. Silicon (Si) and plant-beneficial microorganisms, as green agricultural inputs, exhibit significant limitations when applied individually. This review proposes the mechanisms by which their synergistic interactions enhance resistance to abiotic stress. Silicon optimizes the root microenvironment by regulating auxin-related genes, induces the formation of micropores in the root cortex, and promotes the secretion of photosynthates, thereby providing colonization sites and metabolic substrates for microorganisms. Beneficial microbes, in turn, activate mineral-bound silicon through the secretion of organic acids and upregulate host silicon-transport-related genes, coordinating the passive NIP aquaporin Lsi1 (gene encoding a NIP aquaporin-type silicon influx channel), which mediates monosilicic acid (H₄SiO₄) influx, with the active efflux transporter Lsi2 (silicon efflux transporter protein), thereby enhancing the uptake, loading, and internal distribution of bioavailable silicon in plants. At the physiological level, Si and beneficial microbes may cooperatively promote the physical co-deposition and spatial co-localization of silicon within lignin-enriched cell-wall regions, resulting in Si-associated lignified cell-wall reinforcement that strengthens apoplastic barriers and restricts harmful ion bypass flow. They may also jointly activate antioxidant networks, thereby alleviating stress-induced oxidative damage. Future research should integrate multi-omics approaches and machine learning to identify optimal "Si-microbe" combinations, and develop intelligent formulations based on porous nanosilicon carriers with environment-responsive release properties, thereby providing both a theoretical framework and technical pathway for the sustainable development of green agriculture.