Field evidence of seed coating with the degrading bacterium mitigating atrazine risks to soybeans in black soils

Atrazine is widely applied to control weeds in maize fields, but its residues can impair soybean growth, limiting the effectiveness of maize-soybean rotation or strip intercropping. Field-level strategies to mitigate atrazine risks in soybeans remain limited and often costly. Here, we systematically evaluated the use of seed coating with the atrazine-degrading Paenarthrobacter sp. AT5 in the black soil region of Northeast China, a major soybean production area. Seed coating with strain AT5 significantly reduced the incidence of atrazine phytotoxicity by 67.1 %, increased seedling leaf fresh weight by 26.2 %, and exhibited an upward trend in final plot yield of 22.6 %. Mechanistic analyses revealed that successful root colonization by strain AT5 redirected atrazine metabolism toward a non-phytotoxic hydroxylation pathway while suppressing the still-phytotoxic dealkylation route. Additionally, seed coating with strain AT5 reshaped the plant-associated microbial community, enriching bacterial and fungal taxa with atrazine-degrading or plant-beneficial functions, and restoring the microbial network interactions and community assembly processes disrupted by atrazine. These microbial changes further supported soybean resilience and growth under atrazine stress. Collectively, our findings demonstrate the field-level efficacy of seed coating with the atrazine-degrading bacterium and highlight its potential to shift atrazine phytotoxicity mitigation from broad soil amendment to precision rhizosphere engineering.