An Ultrastructural and Cytochemical Study of Peroxidases, Polyphenoloxidases and Phenols in Xylem of Tomato Plants Infected with<i>Fusarium Oxisporum</i>F. Sp.<i>Lycopersici</i>or<i>Melonis</i>

Abstract

SUMMARYCytochemical reactions for peroxidase, poliphenoloxidase and phenols were performed in compatible and incompatibile combinations. The enhancement of phenolic metabolism in susceptible plants infected with a non-pathogen race, and in resistant plants infected with a pathogen race, confirms their role in resistance mechanisms. The fine localization at an ultrastructural level indicated that these induced processes are connected with adjacent parenchymatous cells and that the enzymatic reactions and their products are strictly associated with the presence of the hyphae.