Genome-wide Screening to Identify Responsive Regulators Involved in the Virulence of pv. .

Two-component systems (TCSs) are critical to the pathogenesis of pv. (). We mutated 55 of 62 genes annotated as responsive regulators (RRs) of TCSs in the genome of strain PXO99A and identified 9 genes involved in virulence. Four (, , , and ) of the 9 genes were previously reported as key regulators of virulence and the other 5 have not been characterized. Lesion lengths on rice leaves inoculated with the mutants were shorter than those of the wild type and were significantly restored with gene complementation. The population density of the 5 mutants in planta was smaller than that of PXO99A at 14 days after inoculation, but the growth curves of the mutants in rich medium were similar to those of the wild type. These newly reported RR genes will facilitate studies on the function of TCSs and of the integrated regulation of TCSs for pathogenesis.