Early burst of reactive oxygen species positively regulates resistance of eggplant against bacterial wilt

Reactive oxygen species (ROS) play a crucial role in the early response to plant biotic and abiotic stresses. In this study, bacterial wilt-resistant and wilt-susceptible eggplants were inoculated with Ralstonia solanacearum and the ROS content was analysed. The result revealed an increased accumulation of hydrogen peroxide (H2O2) and superoxide (O-2(-)) in resistant and susceptible eggplant roots after R.solanacearum inoculation. H2O2 and O-2(-) accumulation increased earlier in the inoculated resistant eggplant root than in the inoculated susceptible eggplant root. Real-time polymerase chain reaction results revealed that respiratory burst oxidase homologue (Rboh) A, RbohB, RbohF and PR1 expression levels increased in inoculated resistant eggplant roots at an early stage (0-60h postinoculation) and were at higher expression levels than those in susceptible eggplant roots. Ascorbate peroxidase, peroxidase and catalase activities were higher in inoculated resistant eggplant roots than in susceptible eggplant roots at the early stage. Hence, an early ROS burst positively regulates bacterial wilt resistance in eggplant.