FUNGICIDAL ACTIVITY OF 2 SPERMIDINE ANALOGS

The potential use of polyamine analogues as inhibitors of polyamine bi osynthesis to control plant pathogenic fungi is well established. Howe ver, all of this information relates to the use of putrescine analogue s and no data exist for spermidine analogues. In the present work, two spermidine analogues, N-1- and N-8-acetylspermidine were evaluated ag ainst powdery mildew on barley. Post-inoculation treatments reduced in fection by 69.7% and 51.5%, respectively. Since the barley powdery mil dew fungus cannot be grown axenically, mode of action studies were und ertaken using the oat leaf-stripe pathogen Pyrenophora avenae. Neither of the analogues had any effect on polyamine biosynthesis in P. avena e grown in vitro. Although the mechanism(s) by which inhibitors affect in vivo fungal growth and in vitro growth may differ, it is unlikely that the antifungal properties of the analogues are the result of a pe rturbation in polyamine biosynthesis.