Elicitors: Their Significance and Primary Modes of Action in the Induction of Plant Defense Reactions

Substances of pathogen origin that induce plant defense reactions, as exemplified by the production of antimicrobial phytoalexins, are known collectively as elicitors. Elicitors appear to be recognized by plant cells via interactions with specific receptors on plant plasma membranes. The elicitor-receptor interactions are presumed to generate signals that then activate nuclear genes involved in plant defense reactions, such as the biosynthesis of phytoalexins. The details of this sequence of molecular events, which lead to plant defense reactions, as well as the roles of elicitors in invoking the general resistance of plants to pathogens and in determining disease specificity, are the focus of this review.