Biochemistry encompasses the study of the chemistry inherent to life and its processes. Any infection symptom caused by a pathological organism in plants is invariably linked to biochemical changes in the tissues. Disease onset in plants stems from a sequence of physiological transformations within host tissues triggered by the pathogen at various stages of disease progression. The pathogen elicits cellular responses by releasing secretions containing auxins, enzymes, and toxins, which modify the metabolism of the host cell. As the disease advances, a complex series of biochemical reactions unfolds in a coordinated and integrated manner. During the localized infection phase, a metabolic equilibrium is established between the host and the parasite (Sharma, 2004).