FUNGICIDAL ACTIVITY OF THE POLYAMINE ANALOG, KETO-PUTRESCINE

The polyamine analogue, keto-putrescine, was shown to provide substantial control of infections by six economically important plant pathogens, with EC50 values ranging between 57 and 82 mg litre-1. However, keto-putrescine was relatively less effective in vitro against Phytophthora infestans, Pyricularia oryzae and Pyrenophora avenae, with EC50 values ranging from 145 to 340 mg litre-1. In contrast, the polyamine analogue N-acetylputrescine had no effect on in-vitro growth of P. avenae or P. oryzae or infection of barley seedlings with powdery mildew. When P. avenae was grown in the presence of keto-putrescine, there were small, insignificant reductions in ornithine decarboxylase activity, with more substantial, significant reductions in S-adenosylmethionine decarboxylase activity. These changes were accompanied by a 43% reduction in spermidine concentration and increased concentrations of spermine and cadaverine.