This book gives an idea about how to carry out biochemical analysis against pathogen and as we know that ability of biocontrol agents to protect plants against pathogens by stimulating the plant defensive mechanisms like hypersensitive response (HR), systemic acquired resistance (SAR), and induced systemic resistance (ISR). At a molecular level, the resistance results in an increase in the concentration of biochemicals such as enzymes which are related to defensive mechanisms, such as phenylalanine ammonia-lyase (PAL) and chalcone synthase (CHS), Peroxidase (PO) and total phenols etc.