Point mutation in CYP51A1 of Venturia inaequalis is associated with low sensitivity to sterol demethylation inhibitors

In 2016, a serious outbreak of apple scab (caused by Venturia inaequalis) in Aomori Prefecture, Japan, resulted from reduced fungal sensitivity to sterol demethylation inhibitors (DMIs). In this study, the lanosterol 14α-demethylase (CYP51A1) gene of V. inaequalis isolates from Aomori Prefecture was analyzed. A nonsynonymous nucleotide polymorphism causing an amino acid substitution from tyrosine to phenylalanine at position 133 (Y133F) in CYP51A1 was closely associated with low sensitivity to DMIs. This is first report of a point mutation in CYP51A1 associated with low sensitivity to DMIs in V. inaequalis.