Elicitins: Key Molecules in Plant – Pathogen Interactions

Abstract

Elicitors, endogenous compounds produced by microbial pathogens, induce defence responses in plants. They rank among chemically nonuniform groups including proteins, glycoproteins, oligo- and polysaccharides and lipids. By multiple mechanisms, elicitors are capable of triggering various modes of plant defence like oxidative burst, hypersensitive response, increased expression of pathogenesis-related proteins and the production of antimicrobial compounds – phytoalexins. Elicitins, secreted by oomycetes from Phytophthora and Pythium spp., are small (10 kDa) protein elicitors structurally similar to lipid-transfer proteins of plant cells and behaving like sterol carrier proteins. In the host plant, elicitins induce a hypersensitive response and development of acquired systemic resistance to many microbial phytopathogens. The review summarizes the current knowledge of the molecular modes of elicitin interaction with plant cells, with a special emphasis on cryptogein as a model elicitin for potential application in the induction of systemic plant resistance.