Distribution Characteristics and Cross‐Media Transmission of Tetracycline Resistance Genes in Black Soil Farmland and Vegetable Under Manure Fertilization

ABSTRACT Antibiotic resistance genes (ARGs) present in livestock and poultry manure can enter the soil and subsequently migrate into vegetables, posing a threat to agricultural product safety and human health. However, the distribution and cross‐medium transmission of ARGs are influenced by multiple factors including the source of manure, soil types and vegetable species. In this study, 27 leafy vegetable samples and their rhizosphere soil, as well as the 39 manure samples were collected from the black soil vegetable area to investigate the distribution characteristics and cross‐media transmission of tetracycline resistance genes (TRGs). The results revealed that 36 out of the 37 target TRGs were detected in manure samples, with the highest relative abundance observed in chicken manure, followed by pig manure. Although 28 TRGs were detected in the soil, their relative abundance was significantly lower than that in the manure. Fourteen TRGs were identified in vegetables, and their total relative abundance was the lowest among the three types of samples. The abundance of TRGs in vegetables decreased in the following order: shallot, celery, and lettuce. Moreover, a total of 12 TRGs and 3 mobile genetic elements (MGEs) were simultaneously detected in manure, soil and vegetable samples. Correlation analysis showed significant positive relationships ( p < 0.05) between TRGs (e.g., tet A and tet B) and MGEs ( tnp A and int I‐1) across all three sample types. MGEs represent the primary drivers of the cross‐media migration of TRGs from manure through soil to endophytic bacteria in vegetables. These findings advance our understanding of the dynamics of ARGs in the soil–plant system and highlight the critical need for improved manure management practices to mitigate the dissemination of ARGs in agroecosystems.