Microbial-Plant Synergy Underpins the Mitigation of Atrazine Phytotoxicity in Soybean by a Multifunctional Bacterial Seed Coating

Residual herbicides from intensive maize cultivation, particularly atrazine, constrain the soybean establishment in rotation or intercropping systems. To address this, we developed a multifunctional seed coating incorporating a synergistic microbial consortium containing the atrazine-degrading Paenarthrobacter sp. AT5 and the plant growth-promoting Arthrobacter sp. A6. Beyond the consortium’s intrinsic traits, the multifunctional seed coating activated systemic resistance in soybeans by upregulating jasmonic acid, salicylic acid, and isoflavonoid biosynthesis. Elevated isoflavonoids selectively reshaped the soybean microbiome, enriching bacterial taxa with potential capacities for atrazine degradation and growth promotion. This plant-microbe feedback loop redirected atrazine metabolic pathways toward accelerated degradation and enhanced conversion to the less phytotoxic hydroxyatrazine. Collectively, the multifunctional seed coating mitigated phytotoxic symptoms and promoted soybean growth by coupling efficient microbial detoxification with reinforced plant defense. Our results uncover a microbiome-mediated phytoprotection mechanism and demonstrate a scalable strategy to mitigate legacy herbicide effects, thereby improving crop establishment and sustainable agricultural productivity.