Many plant diseases are caused by bacterial pathogens. Various factors of a bacterial pathogen play key role infection process to lead distinct levels of plant damage. However, many defense responses can be activated by plants during the infection process. Thus, studies on interaction between pathogenicity of bacterial pathogen and defense response of plant are important issues in generating plant with disease resistance. These issues will be discussed in the course; we will focus on pathogenicity of bacterial pathogens, recognition of bacterial pathogens on plants, production of reactive oxygen species in plants, plant immune response and biocontrol.