Partial purification of the elicitor from Pseudomonas syringae pv tabaci was carried out by anion-exchange chromatography and SDS-PAGE. A DEAE-cellulose (DE-52, Whatman, Maidstone, UK) column was equilibrated with 10 mM Tris–HCl at pH 7.5, loaded with crude elicitor preparation in the same buffer, and eluted with a linear gradient from 0 to 0.5 M NaCl. Elicitor active fractions were separated by SDS-PAGE and stained with Coomassie blue. The dried gel was cut into 2 mm segments, the segments were eluted overnight in 0.1% SDS, and the eluates were tested for induction of the alkalinization response in tomato cells at a dose of 1 ml eluate per ml of suspension.