Differential accumulation of beta-1,3-glucanase and chitinase isoforms in tomato roots in response to colonization by either pathogenic or non-pathogenic strains of Fusarium oxysporum

The time-course accumulation patterns of beta-1,3-glucanase and chitinase i soforms in susceptible tomato roots inoculated with either pathogenic or no n-pathogenic strains of Fusarium oxysporum were investigated with regard to the fungal dynamics of root colonization. Eleven days after inoculation, i soelectric focusing gel electrophoresis showed an overall increased activit y of constitutive glycosidase isoforms in response to infection by F. oxysp orum f. sp. lycopersici that did not occur in roots colonized with non-path ogenic strains. As detected by anodic polyacrylamide gel electrophoresis fo r acidic proteins, the strains of F: oxysporum f. sp. lycopersici induced t he expression of at least one additional beta-1,3-glucanase. This isoform, supposedly of host origin, may serve as a biochemical marker of pathogenici ty in fusarium wilt of tomato. The present study does not seem to support t he view that the post-infectional accumulation of chitinases and beta-1,3-g lucanases might play a significant role in restricting the root colonizatio n by pathogenic strains of F. oxysporum.