Phylogenetic Diversity and Quantitative PCR Detection of Erwinia amylovora in Xinjiang, China

Fire blight, a devastating bacterial disease affecting Rosaceae plants, particularly pear and apple, has recently emerged in China’s Xinjiang Uyghur Autonomous Region, causing significant damage to the local Pyrus sinkiangensis industry. Phylogenetic analysis of identified Erwinia amylovora strains revealed that all eight Xinjiang isolates belonged to the A-genotype in CRR1 genotyping tests, aligning with findings from 53 strains isolated in Kazakhstan and Kyrgyzstan between 2011 and 2019. A quantitative PCR detection system based on the trp gene sequence was developed and optimized. The system performed optimally with primer concentrations of 200 nmol/L and an annealing temperature of 60 °C. The detection limits were established at 102 CFU/mL for bacterial suspensions and 0.05 pg/µL for bacterial DNA, demonstrating 100-fold greater sensitivity than conventional PCR. The system successfully detected E. amylovora in all 31 tested samples (25 symptomatic and six asymptomatic plant tissues), confirming the reliability of the detection method for pear fire blight.