ABSTRACT
Crops are usually attacked by many pathogens and they respond by the activation and production of defense genes, the formation of ROS, the synthesis of pathogenesis-related proteins, localized cell wall enforcement and the induction of antimicrobial compounds. Plants use innate defense mechanisms toward pathogens, including the induction of substances that have antimicrobial activity which are known as phytoalexins (PhA). PhA production is now considered as an important defense mechanism toward microbial infection through a broad spectrum of various secondary metabolites induced. Molecular approaches are helping to resolve some mechanisms and the complexity of these bioactive PhA compounds. This chapter focuses on the biosynthesis and regulation of various PhA compounds and its role in plant defense. Moreover, this chapter also discusses some of the PhA induced by plants from different families. This includes the very recently identified kauralexins and zealexins induced by maize, and the biosynthesis and regulation of PhA induced by rice.
