Appressorium formation assays with the pic5 mutant. (A) Conidia from the wild-type 70-15, pic5 mutants ML4 and ML13, and complemented transformant MF2 (pic5/PIC5) were incubated on glass coverslips and onion epidermal cells for 24 h. Over 70% of the pic5 germ tubes formed more than one appressorium on individual germ tubes. (B) Appressoria formed by the pic5 mutant strains ML4 and ML13 on glass coverslips in the presence of 5 mM cAMP, 10 μM cutin monomer 1,16-hexadecanediol, and bee waxes after incubation for 24 h. The defect of the pic5 mutant in appressorium formation was suppressed by 5 mM cAMP. Bar = 10 μm.