ABSTRACT
Acknowledgments .......................................................................................................................... 277 References ...................................................................................................................................... 277
Elicitors are produced by plant pathogens and, in certain pathogen-plant interactions, elicitors induce plants to activate their defense responses. The implicit recognition event is somehow transduced, by the plant, into the appearence of defense responses such as hypersensitivity, phytoalexin and ethylene accumulation, systemic acquired resistance, and reactive oxygen species. 1·4 This chapter focuses on a proteinaceous elicitor called elicitin, which activates these defense responses primarily in cultivars of Nicotiana tabacum, or tobacco, and some cultivars of Raphanus sativa, or radish.5-11
Elicitins are small ( 10.2 to 10.4 kDa), extracellular proteins secreted by species of the oomycete Phytophthora. 12 Found at up to 3 11M in culture fluids, they are easily purified by adsorption chromatography and reverse-phase, high-pressure liquid chromatography (RP-HPLC). They induce a variety of defense responses in tobacco at nanomolar doses, but their interaction with tobacco, as well as their role in Phytophthora biology, remains mechanistically obscure.
