Abstract:The reactive oxygen intermediates（ROI）and the nitric oxide（NO）play an important role in the establishment of resistance to plant diseases during interactions between hosts and pathogens. The plants produce a biphasic oxidative burst in incompatible interactions,and the concentration of NO increases in plant. Many oxidases may catalyze the generation of ROI.The ROI and NO trigger off the hypersensitive response(HR) in regional cells and the systemic acquired resistance(SAR) in total plant tissues through redox signaling.