Involvement of gluconeogenic pathway in virulence of Xanthomonas oryzae pv. oryzae

Xanthomonas oryzae pv. oryzae causes bacterial leaf blight, one of the most widespread and destructive bacterial diseases of rice. A phosphoenolpyruvate synthase (ppsA)-disrupted mutant OSPAM was generated by homologous suicide plasmid integration. The mutant was unable to grow in medium with pyruvate or C-4-dicarboxylates as the sole carbon source, compared with the wild-type, indicating a disruption in ppsA function. The mutant showed a reduction in virulence on rice but still induced a hypersensitive response in tobacco. When the mutant was complemented, the response was recovered to wild-type. These results suggested that X. oryzae pv. oryzae possesses only PPSA route in gluconeogenesis, which is necessary for virulence.