Inhibition of mycelial growth and sporidial formation in the wheat pathogenNeovossia indica by a polyamine biosynthetic inhibitor

DL-α-Difluoromethylornithine (DFMO), a specific suicide inhibitor of the polyamine biosynthetic enzyme ornithine decarboxylase (EC 4.1.1.17), strongly inhibited mycelial growth and sporidial formation of the wheat pathogen,Neovossia indica, in vitro, while DL-α-difluoromethylarginine (DFMA), the analogous suicide inhibitor of arginine decarboxylase (EC 4.1.1.19), did not. The inhibited mycelial growth and sporidial formation were not only restored by putrescine (polyamine) addition, but were actually enhanced in the putrescine + DFMO cultures. Besides altering mycelial growth and morphology, DFMO also reduced the cell size drastically. The inhibition of fungal polyamine biosynthesis is discussed in relation to selective control of plant disease.