Biochemistry of the Host Pathogen Interaction

Biochemical studies on the growth and survival of a pathogen and the changes it induces in its host can ultimately lead to a better understanding of the disease development, its epidemiology, and its control. Ideal prerequisites for meaningful studies of the biochemistry of the host-parasite interaction are (a) a clear understanding of the genetic control of virulence and avirulence in the parasite and of susceptibility and resistance in the host, (b) precise histological and cytological descriptions of spore germination and infection and the establishment and development of the host-pathogen interaction, and (c) the availability of methods for maintaining the pathogen alone and in combinations with its host, under controlled conditions. Unfortunately, these criteria have not yet been satisfactorily met for downy mildew of crucifers. The biosynthesis of the defence-related compounds like camalexin, salicylic acid, and lignin in Arabidopsis provides resistance to crucifers against downy mildew pathogen.