Pantoea ananatis as the Emerging Causal Agent of Novel Bacterial Leaf Blight in Rice: Characterization and Management in Anhui, China.

Since its emergence in 2020, a novel bacterial leaf blight caused by Pantoea ananatis has posed a serious threat to rice production in Anhui Province, China. Through verification via Koch's postulates and three years of field monitoring, P. ananatis strain HQ01 was identified as the dominant pathogen, exhibiting high virulence even at low inoculum concentrations (10² CFU/mL). Genomic analysis further revealed virulence-associated traits, including type III, IV, and VI secretion systems (T3SS/T4SS/T6SS), iron acquisition genes, and 160 carbohydrate-active enzymes linked to plant cell wall degradation. Meanwhile, resistance screening of 21 rice cultivars showed widespread susceptibility, with 95% of varieties classified as susceptible. In parallel, in vitro and in vivo trials identified tetramycin and zinc thiazole as the most effective chemical candidates. Despite these findings, control strategies remain inadequate for managing severe outbreaks. This study thus highlights the urgent need to develop resistant cultivars and sustainable bactericides to combat this emerging disease.