Effect of allopurinol treatment on the development of rust diseases of kidney-bean, broad-bean and wheat plants

The effect of a xanthine oxidase (XO) inhibitor, allopurinol, was studied in three host-rust interactions. Application of allopurinol in an incompatible interaction (wheat– Puccinia recondita f. sp. tritici ) did not significantly alter symptom expression nor result in an increase in lipid peroxidation (LP) and electrolyte leakage as compared to non-treated control plants. On the other hand, application of allopurinol in three compatible host–rust interactions suppressed, in a concentration-dependent manner, the formation of uredospores which was accompanied by a transient increase in electrolyte leakage and LP during the biotrophic fungal growth (5–6 days after infection). These results suggest that (i) allopurinol can inhibit fungal growth in later developmental stage (s) developing only in compatible hosts and (ii) XO is not the primary source of the generation of reactive oxygen species (ROS) in incompatible rust combinations.