This course deals with; Infection process of fungi, bacteria, viruses and nematodes; comparative analysis of biochemical and physiological changes in diseased and healthy plants; influence of plant pathogens on photosynthesis, respiration, translocation, transpiration, cell wall composition and metabolism, nucleic acid and protein metabolism; changes in secondary metabolites, membrane alterations; growth regulators phytoallexins and toxins; nature of morphological and biochemical resistance in host plants; energy use and metabolic regulation in plant-pathogen interactions.