An Emerging Bacterial Leaf Disease in Rice Caused by Pantoea ananatis and Pantoea eucalypti in Northeast China

Rice production faces new challenges from emerging diseases due to intensive cultivation practices and climate warming in China. A new rice leaf bacterial disease has recently occurred in Northeast China. The symptoms of the disease are similar to those of bacterial leaf blight. Disease lesions spread along leaf edges and are later dried up due to water loss. In this study, 17 bacterial isolates were identified as the causal agents of the new disease following Koch's postulates. These strains are categorized into two groups based on colony morphology and molecular characterization. Phylogenetic analysis using the five housekeeping genes <i>leuS</i>, <i>gyrB</i>, <i>fusA</i>, <i>pyrG</i>, and <i>rplB</i> reveals that the two groups of the isolates belong to <i>Pantoea ananatis</i> and <i>P. eucalypti</i>, respectively. The new rice disease is caused by <i>P. ananatis</i>, <i>P. eucalypti</i>, or a combination of both bacterial species. A complete genome map has also been assembled for <i>P. eucalypti</i>. Meanwhile, some important virulence factors have been predicted based on gene annotation and determination of extracellular enzymes. Collectively, this study represents the first report of a new rice leaf disease caused by <i>P. eucalypti</i> and the first high-quality genome assembly of <i>P. eucalypti</i> that infects rice leaves.