Differential production of superoxide dismutase and catalase isozymes during infection of wheat by a Fusarium proliferatum -like fungal isolate

AOS are produced during interactions between pathogens and incompatible and compatible plant hosts. Wheat cv. Super Dwarf infected with a Fusarium proliferatum -like species showed increased deposition of lignin-like polymers and dimers of ferulic acid in plant cell wall structures denoting phenolic oxidation. Consequently, we examined whether enzymes connected with AOS metabolism were modified during the interaction between wheat and this Fusarium isolate. Neither SOD nor catalase activities of wheat were altered by Fusarium -infection of sheath tissue. In liquid in vitro cultures, Fusarium produced three anionic SODs, and anionic and cationic catalase isozymes. OneFusarium MnSOD was expressed in infected wheat, while one Cu/ZnSOD and a second MnSOD were not detected. The Cu/ZnSOD was not expressed during growth on carbon- or nitrogen-limited cultures. The fungal anionic catalases that were highly expressed in carbon-limited in vitro culture, but not the cationic catalase, were detected in Fusarium -infected wheat tissue. Thus, specific isozymes of both fungal SOD and catalase appear not to be produced in the wheat sheath. The fungal enzyme expression patterns are consistent with the fungus experiencing nutrient limitation and/or oxidative stress during its process of colonization of the wheat sheath.