The Role of Toxin(s) Produced by Germinating Spores of Pyricularia oryzae in Pathogenesis

Pyricularia oryzae produced toxin(s) during spore germination which induced susceptibility to infection by non-pathogenic Alternaria alternata of rice leaves. The induced susceptibility was independent of the compatibility between the races of blast fungi used for obtaining the toxin(s) and the rice cultivars used for bioassay. Susceptibility was also induced in other susceptible species (e.g. barley, Italian ryegrass, perennial ryegrass and wheat), results suggesting that the toxin(s) are host-selective and determine the host specificity at plant species level.