INHIBITORY EFFECT OF O-2- ANION GENERATED IN-VITRO ON PHYTOPHTHORA-INFESTANS (MONT) DEBARY

Zoospores, cystospores and mycelia of Phytophthora infestans race 2.3. 4 have been affected when exposed in vitro to a superoxide anion (O2-) generating system. Zoospores showed immobilization and then bursting. Damage to the zoospores increased by increasing the period of treatme nt in the superoxide generating system. However, this effect was preve nted by adding active superoxide dismutase (SOD) enzyme to the reactio n mixture. In the case of cystospores no bursting occurred but the ger mination of spores was delayed and the length of germ tubes decreased in dependence of the light exposition time. The radial growth of the f ungus was also restricted by the action of the superoxide anion. This restriction depended on the time of illumination and on the concentrat ion of superoxide-producing substances (i.e. riboflavin/methionine sys tem in the presence of light).