The mode of action of S-benzyl O,O-di-isoproyl phosphorothiaote and of dicloran on aspergillus nidulans

S-Benzyl O, O-di-isopropyl phosphorothoiate (IBP) and dicloran inhibit spore germination and mycelial growth in Aspergillus nidulans. The physiological and biochemical effects of both fungicides were studied at their Ec₅₀ values (EC₅₀ is the concentration that inhibits mycelial growth by 50%). IBP inhibited chitin synthase activity in vivo and in vitro and this appeared to be the primary mode of action, although it also caused a slight decrease in total lipid synthesis. Dicloran caused an increase in nucleic acid synthesis, particularly RNA synthesis, but a decrease in total lipid biosynthesis.