Elicitins from Phytophthora and basic resistance in tobacco.
Elicitins are a family of small proteins secreted by species of Phytophthora. They are thought to be major determinants of the resistance response of tobacco against these oomycetes, since purified elicitins, alone and at low concentrations, can induce vigorous defense responses in tobacco (i.e., hypersensitive cell death and resistance against subsequent pathogen attack), and in vitro elicitin production by Phytophthora isolates is strongly negatively correlated with their pathogenicity on tobacco plants. A number of elicitins have been purified and their amino acid sequences have been determined and found to be conserved. A three-dimensional structure for elicitin is emerging from nuclear magnetic resonance studies. Two structural classes, alpha and beta, are distinguished by their biological effects when applied to decapitated stems or petioles; the beta class causes more necrosis on leaves and provides better subsequent protection against pathogen attack. However, both these classes of elicitins will similarly cause necrosis when each is, instead, directly infiltrated into tobacco leaf panels. Effects of elicitins on tobacco cells include rapid electrolyte leakage, changes in protein phosphorylation and amounts of active oxygen species, and later production of ethylene and capsidiol. The sites of initial interaction with tobacco cells are unknown, but the interaction appears to induce general defense-related responses.
Yu
L M
LM
Center for Engineering Plants for Resistance Against Pathogens (CEPRAP), University of California, Davis 95616, USA.
D020418:Algal Proteins; D000595:Amino Acid Sequence; D002478:Cells, Cultured; D005656:Fungal Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000494:pharmacology*; D007113:Immunity, Innate; D008969:Molecular Sequence Data; D009336:Necrosis; D010838:Phytophthora / Q000472:pathogenicity / Q000502:physiology*; D010935:Plant Diseases; D010947:Plants, Toxic; D011506:Proteins; D017386:Sequence Homology, Amino Acid; D014026:Nicotiana / Q000382:microbiology* / Q000502:physiology*
D020418:Algal Proteins; D005656:Fungal Proteins; D011506:Proteins; C085101:elicitin, Phytophthora