Cytokinin inhibits the growth ofLeptosphaeria maculansandAlternaria brassicae

Blackleg and blackspot are economically important diseases of canola caused by Leptosphaeria maculans and Alternaria brassicae, respectively, and can lead to significant crop losses. In this study, we investigated the effects of cytokinins on the symptoms caused by these two pathogens. We observed that cytokinin, especially 6-benzyl amino purine, was able to significantly reduce disease symptoms and mycelial growth within plant tissues. This cytokinin was also able to inhibit the in vitro growth of both fungi. Other cytokinins such as kinetin or adenine hemisulfate were unable to inhibit fungal growth in vitro, suggesting that the presence of a benzene ring structure is required for the inhibitory effects observed. Our findings are discussed within the context of plant–pathogen interactions.