Effect of probenazole on the activities of enzymes related to the resistant reaction in rice plant.

The activities of enzymes including peroxidase, polyphenoloxidase, phenylalanine ammonialyase, tyrosine ammonia-lyase or catechol-O-methyltransferase in rice leaves were surveyed to elucidate the mechanism of action of probenazole in connection with the resistant reaction of host plant against rice blast fungus. The activities of enzymes were increased evidently in the treated-inoculated rice leaves with probenazole and rice blast fungus conidia than in the leaves of treated-noninoculated, nontreated-inoculated or nontreated-noninoculated one. The above results seem to be closely correlated with the facilitated formation of a physical barrier in and around the invaded cell, which was observed microscopically.