PROTEIN(S) FROM THE GRAM-POSITIVE BACTERIUM CLAVIBACTER-MICHIGANENSISSUBSP MICHIGANENSIS INDUCES A HYPERSENSITIVE RESPONSE IN PLANTS

The gram-positive tomato pathogen Clavibacter michiganensis subsp. mic higanensis induced a local necrotic response on four-o'clock (Mirabili s jalapa) and tobacco (Nicotiana tabacum) plants. This necrosis respon se was characteristic of the hypersensitive response (HR). The cell-fr ee culture supernatant from strain CMM623 also induced a necrosis that was phenotypically similar to that induced by the bacteria. Inhibitor s of plant metabolism suppressed the necrotic reaction of both M. jala pa and tobacco. The HR-inducing activity present in the supernatant wa s heat stable, sensitive to proteases; and had hn apparent molecular m ass in the range of 35 to 50 kDa as determined by sodium dodecyl sulfa te-polyacrylamide gel electrophoresis. The properties observed for the necrosis-inducing activity resembled bacteria.