In filamentous fungi,
pyrimidine auxotrophs obtained through inactivation of the
OMP decarboxylase gene (usually designated pyrG) are auxotrophic
for uridine and/or uracil and are resistant to 5-FOA
[5, 6]. The generation of 5-FOA-resistant pyrG mutants has
been reported in other fungi including A. aculeatus, A. niger,
Sclerotinia sclerotiorum, and Trichoderma reesei [5, 7–9].