ALTERATIONS IN SUPEROXIDE-DISMUTASE AND CATALASE IN FUSARIUM-OXYSPORUM DURING STARVATION-INDUCED DIFFERENTIATION

Vegetative hyphae of Fusarium oxysporum differentiate into chlamydospo re by triggering with carbon-starvation. The occurrent changes in the cellular detoxifying defenses against superoxide and hydrogen peroxide : superoxide dismutase (SOD) and catalase, were examined. Although the re was a little change in catalase, a dramatic change in SOD was obser ved during the differentiation. In vegetative hyphae of F. oxysporum f . sp. raphani, three isozymes of SOD, all of which were not inhibited by hydrogen peroxide and cyanide, were present whereas in chlamydospor e an isoenzyme, which was inhibited by hydrogen peroxide but not by cy anide, was present. Thus, as differentiation proceeded, Mn-type SOD di sappeared and an Fe-type SOD appeared. The results suggest that the Fe -type SOD is specifically expressed during chlamydospore formation and that active intermediates of oxygen and/or its scavenging enzymes par ticipate in the differentiation of Fusarium oxysporum.