Mutation of alkyl hydroperoxide reductase gene ahpC of Xanthomonas oryzae pv. oryzae affects hydrogen peroxide accumulation during the rice–pathogen interaction

Hydrogen peroxide (H2O2) is usually generated by normal aerobic respiration of pathogens and by the host defense response during plant–pathogen interactions. In this study, histochemical localization of H2O2 accumulation in rice inoculated with the wild-type strain (PXO99A) and the gene deletion mutant (ΔahpC) of alkyl hydroperoxide reductase subunit C (AhpC) of Xanthomonas oryzae pv. oryzae (Xoo), the bacterial blight pathogen of rice, was analyzed. The ΔahpC mutant displayed a significant decrease in endogenous H2O2 accumulation which was induced by the compensatory increase in H2O2 scavenging activity. The change in the bacterial endogenous H2O2 level affected the total amount of H2O2 accumulation during the interaction with rice plants. These results suggested that Xoo contributes to H2O2 accumulation in rice in a compatible interaction, and pathogen-driving H2O2 is in association with cell collapse of rice.