CHARACTERIZATION OF ANIONIC PEROXIDASES IN TOMATO ISOLINES INFECTED BY MELOIDOGYNE-INCOGNITA

Changes in peroxidase activity during nematode infection were studied using root extracts of tomato near-isogenic lines differing in resista nce to Meloidogyne incognita. Total peroxidase activity increased slig htly in crude extracts of four susceptible isolines but doubled in two resistant lines, Monita and Motaci. Nematode infection enhanced level s of both p-phenylenediamine-pyrocatechol oxidase and syringaldazine o xidase 7 days after inoculation, especially in resistant lines. This e levated peroxidase activity in resistant isolines was caused by an inc rease in anionic peroxidase activity. These enzymes, which likely are involved in lignification, were isolated and purified from tomato isol ines by ammonium sulfate precipitation, high performance ion-exchange chromatography, and gel electrophoresis. The purified anionic peroxida se extracts contained an electrophoretic band with Rf 0.51 that was pr esent in extracts of infected but not uninfected roots.