Antimicrobial Resistance Profiling and Identification of Putative Resistance Genes in Erwinia amylovora from Xinjiang, China

Fire blight, caused by Erwinia amylovora (Burrill) Winslow et al., is a destructive and highly contagious bacterial disease of pear and other rosaceous plants. This pathogen spreads globally and leads to considerable economic losses in fruit production. In this study, three E. amylovora strains with reduced susceptibility to tetramycin were isolated from Xinjiang, China. Hybrid whole-genome sequencing combining Oxford Nanopore and Illumina platforms was performed for genome assembly and functional annotation to screen candidate genes and genomic elements potentially linked to tetramycin response. Nine candidate genes were identified on the chromosomes of the three strains. Among them, five were annotated as efflux-related genes, three were associated with antibiotic target modification, and one was related to antibiotic inactivation. The relative expression level of nine candidate resistance genes across the three resistant strains was analyzed using quantitative PCR. This work provides preliminary genomic clues for characterizing local E. amylovora populations in China, and supports the future development of molecular markers for resistance monitoring and pathogen detection, which may facilitate integrated fire blight management.